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annotate Lib/csv.py @ 62799:dcc2e8bf64cf

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Fix: Issue9091 Minor documentation clarification.
author Senthil Kumaran <orsenthil@gmail.com>
date Mon, 05 Jul 2010 11:41:42 +0000
parents 77de7b1bcd59
children 9e4a2809e55c
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1
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2 """
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3 csv.py - read/write/investigate CSV files
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4 """
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5
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6 import re
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7 from _csv import Error, __version__, writer, reader, register_dialect, \
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8 unregister_dialect, get_dialect, list_dialects, \
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9 field_size_limit, \
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10 QUOTE_MINIMAL, QUOTE_ALL, QUOTE_NONNUMERIC, QUOTE_NONE, \
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11 __doc__
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12 from _csv import Dialect as _Dialect
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13
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14 from io import StringIO
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15
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16 __all__ = [ "QUOTE_MINIMAL", "QUOTE_ALL", "QUOTE_NONNUMERIC", "QUOTE_NONE",
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17 "Error", "Dialect", "__doc__", "excel", "excel_tab",
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18 "field_size_limit", "reader", "writer",
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19 "register_dialect", "get_dialect", "list_dialects", "Sniffer",
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20 "unregister_dialect", "__version__", "DictReader", "DictWriter" ]
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21
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22 class Dialect:
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23 """Describe an Excel dialect.
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24
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25 This must be subclassed (see csv.excel). Valid attributes are:
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26 delimiter, quotechar, escapechar, doublequote, skipinitialspace,
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27 lineterminator, quoting.
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28
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29 """
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30 _name = ""
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31 _valid = False
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32 # placeholders
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33 delimiter = None
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34 quotechar = None
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35 escapechar = None
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36 doublequote = None
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37 skipinitialspace = None
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38 lineterminator = None
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39 quoting = None
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40
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41 def __init__(self):
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42 if self.__class__ != Dialect:
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43 self._valid = True
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44 self._validate()
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45
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46 def _validate(self):
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47 try:
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48 _Dialect(self)
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49 except TypeError as e:
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50 # We do this for compatibility with py2.3
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51 raise Error(str(e))
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52
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53 class excel(Dialect):
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54 """Describe the usual properties of Excel-generated CSV files."""
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55 delimiter = ','
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56 quotechar = '"'
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57 doublequote = True
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58 skipinitialspace = False
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59 lineterminator = '\r\n'
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60 quoting = QUOTE_MINIMAL
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61 register_dialect("excel", excel)
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62
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63 class excel_tab(excel):
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64 """Describe the usual properties of Excel-generated TAB-delimited files."""
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65 delimiter = '\t'
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66 register_dialect("excel-tab", excel_tab)
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67
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68
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69 class DictReader:
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70 def __init__(self, f, fieldnames=None, restkey=None, restval=None,
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71 dialect="excel", *args, **kwds):
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72 self._fieldnames = fieldnames # list of keys for the dict
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73 self.restkey = restkey # key to catch long rows
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74 self.restval = restval # default value for short rows
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75 self.reader = reader(f, dialect, *args, **kwds)
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76 self.dialect = dialect
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77 self.line_num = 0
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78
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79 def __iter__(self):
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80 return self
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81
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82 @property
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83 def fieldnames(self):
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84 if self._fieldnames is None:
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85 try:
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86 self._fieldnames = next(self.reader)
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87 except StopIteration:
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88 pass
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89 self.line_num = self.reader.line_num
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90 return self._fieldnames
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91
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92 @fieldnames.setter
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93 def fieldnames(self, value):
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94 self._fieldnames = value
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95
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96 def __next__(self):
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97 if self.line_num == 0:
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98 # Used only for its side effect.
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99 self.fieldnames
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100 row = next(self.reader)
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101 self.line_num = self.reader.line_num
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102
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103 # unlike the basic reader, we prefer not to return blanks,
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104 # because we will typically wind up with a dict full of None
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105 # values
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106 while row == []:
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107 row = next(self.reader)
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108 d = dict(zip(self.fieldnames, row))
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109 lf = len(self.fieldnames)
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110 lr = len(row)
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111 if lf < lr:
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112 d[self.restkey] = row[lf:]
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113 elif lf > lr:
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114 for key in self.fieldnames[lr:]:
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115 d[key] = self.restval
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116 return d
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117
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118
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119 class DictWriter:
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120 def __init__(self, f, fieldnames, restval="", extrasaction="raise",
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121 dialect="excel", *args, **kwds):
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122 self.fieldnames = fieldnames # list of keys for the dict
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123 self.restval = restval # for writing short dicts
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124 if extrasaction.lower() not in ("raise", "ignore"):
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125 raise ValueError("extrasaction (%s) must be 'raise' or 'ignore'"
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126 % extrasaction)
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127 self.extrasaction = extrasaction
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128 self.writer = writer(f, dialect, *args, **kwds)
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129
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130 def writeheader(self):
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131 header = dict(zip(self.fieldnames, self.fieldnames))
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132 self.writerow(header)
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133
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134 def _dict_to_list(self, rowdict):
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135 if self.extrasaction == "raise":
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136 wrong_fields = [k for k in rowdict if k not in self.fieldnames]
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137 if wrong_fields:
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138 raise ValueError("dict contains fields not in fieldnames: "
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139 + ", ".join(wrong_fields))
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140 return [rowdict.get(key, self.restval) for key in self.fieldnames]
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141
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142 def writerow(self, rowdict):
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143 return self.writer.writerow(self._dict_to_list(rowdict))
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144
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145 def writerows(self, rowdicts):
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146 rows = []
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147 for rowdict in rowdicts:
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148 rows.append(self._dict_to_list(rowdict))
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149 return self.writer.writerows(rows)
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150
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151 # Guard Sniffer's type checking against builds that exclude complex()
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152 try:
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153 complex
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154 except NameError:
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155 complex = float
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156
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157 class Sniffer:
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158 '''
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159 "Sniffs" the format of a CSV file (i.e. delimiter, quotechar)
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160 Returns a Dialect object.
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161 '''
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162 def __init__(self):
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163 # in case there is more than one possible delimiter
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164 self.preferred = [',', '\t', ';', ' ', ':']
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165
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166
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167 def sniff(self, sample, delimiters=None):
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168 """
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169 Returns a dialect (or None) corresponding to the sample
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170 """
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171
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172 quotechar, doublequote, delimiter, skipinitialspace = \
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173 self._guess_quote_and_delimiter(sample, delimiters)
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174 if not delimiter:
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175 delimiter, skipinitialspace = self._guess_delimiter(sample,
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176 delimiters)
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177
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178 if not delimiter:
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179 raise Error("Could not determine delimiter")
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180
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181 class dialect(Dialect):
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182 _name = "sniffed"
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183 lineterminator = '\r\n'
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184 quoting = QUOTE_MINIMAL
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185 # escapechar = ''
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186
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187 dialect.doublequote = doublequote
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188 dialect.delimiter = delimiter
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189 # _csv.reader won't accept a quotechar of ''
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190 dialect.quotechar = quotechar or '"'
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191 dialect.skipinitialspace = skipinitialspace
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192
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193 return dialect
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194
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195
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196 def _guess_quote_and_delimiter(self, data, delimiters):
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197 """
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198 Looks for text enclosed between two identical quotes
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199 (the probable quotechar) which are preceded and followed
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200 by the same character (the probable delimiter).
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201 For example:
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202 ,'some text',
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203 The quote with the most wins, same with the delimiter.
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204 If there is no quotechar the delimiter can't be determined
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205 this way.
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206 """
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207
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208 matches = []
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209 for restr in ('(?P<delim>[^\w\n"\'])(?P<space> ?)(?P<quote>["\']).*?(?P=quote)(?P=delim)', # ,".*?",
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210 '(?:^|\n)(?P<quote>["\']).*?(?P=quote)(?P<delim>[^\w\n"\'])(?P<space> ?)', # ".*?",
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211 '(?P<delim>>[^\w\n"\'])(?P<space> ?)(?P<quote>["\']).*?(?P=quote)(?:$|\n)', # ,".*?"
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212 '(?:^|\n)(?P<quote>["\']).*?(?P=quote)(?:$|\n)'): # ".*?" (no delim, no space)
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213 regexp = re.compile(restr, re.DOTALL | re.MULTILINE)
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214 matches = regexp.findall(data)
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215 if matches:
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216 break
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217
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218 if not matches:
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219 # (quotechar, doublequote, delimiter, skipinitialspace)
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220 return ('', False, None, 0)
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221 quotes = {}
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222 delims = {}
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223 spaces = 0
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224 for m in matches:
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225 n = regexp.groupindex['quote'] - 1
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226 key = m[n]
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227 if key:
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228 quotes[key] = quotes.get(key, 0) + 1
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229 try:
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230 n = regexp.groupindex['delim'] - 1
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231 key = m[n]
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232 except KeyError:
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233 continue
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234 if key and (delimiters is None or key in delimiters):
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235 delims[key] = delims.get(key, 0) + 1
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236 try:
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237 n = regexp.groupindex['space'] - 1
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238 except KeyError:
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239 continue
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240 if m[n]:
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241 spaces += 1
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242
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243 quotechar = max(quotes, key=quotes.get)
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244
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245 if delims:
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246 delim = max(delims, key=delims.get)
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247 skipinitialspace = delims[delim] == spaces
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248 if delim == '\n': # most likely a file with a single column
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249 delim = ''
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250 else:
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251 # there is *no* delimiter, it's a single column of quoted data
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252 delim = ''
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253 skipinitialspace = 0
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254
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255 # if we see an extra quote between delimiters, we've got a
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256 # double quoted format
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257 dq_regexp = re.compile(r"((%(delim)s)|^)\W*%(quote)s[^%(delim)s\n]*%(quote)s[^%(delim)s\n]*%(quote)s\W*((%(delim)s)|$)" % \
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258 {'delim':delim, 'quote':quotechar}, re.MULTILINE)
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259
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260
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261
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262 if dq_regexp.search(data):
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263 doublequote = True
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264 else:
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265 doublequote = False
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266
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267 return (quotechar, doublequote, delim, skipinitialspace)
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268
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269
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270 def _guess_delimiter(self, data, delimiters):
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271 """
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272 The delimiter /should/ occur the same number of times on
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273 each row. However, due to malformed data, it may not. We don't want
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274 an all or nothing approach, so we allow for small variations in this
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275 number.
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276 1) build a table of the frequency of each character on every line.
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277 2) build a table of freqencies of this frequency (meta-frequency?),
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278 e.g. 'x occurred 5 times in 10 rows, 6 times in 1000 rows,
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279 7 times in 2 rows'
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280 3) use the mode of the meta-frequency to determine the /expected/
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281 frequency for that character
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282 4) find out how often the character actually meets that goal
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283 5) the character that best meets its goal is the delimiter
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284 For performance reasons, the data is evaluated in chunks, so it can
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285 try and evaluate the smallest portion of the data possible, evaluating
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286 additional chunks as necessary.
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287 """
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288
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289 data = list(filter(None, data.split('\n')))
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290
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parents:
diff changeset
291 ascii = [chr(c) for c in range(127)] # 7-bit ASCII
0c950e3323ee cvs is going to be a module again
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parents:
diff changeset
292
0c950e3323ee cvs is going to be a module again
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parents:
diff changeset
293 # build frequency tables
0c950e3323ee cvs is going to be a module again
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parents:
diff changeset
294 chunkLength = min(10, len(data))
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parents:
diff changeset
295 iteration = 0
0c950e3323ee cvs is going to be a module again
Skip Montanaro <skip@pobox.com>
parents:
diff changeset
296 charFrequency = {}
0c950e3323ee cvs is going to be a module again
Skip Montanaro <skip@pobox.com>
parents:
diff changeset
297 modes = {}
0c950e3323ee cvs is going to be a module again
Skip Montanaro <skip@pobox.com>
parents:
diff changeset
298 delims = {}
0c950e3323ee cvs is going to be a module again
Skip Montanaro <skip@pobox.com>
parents:
diff changeset
299 start, end = 0, min(chunkLength, len(data))
0c950e3323ee cvs is going to be a module again
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parents:
diff changeset
300 while start < len(data):
0c950e3323ee cvs is going to be a module again
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parents:
diff changeset
301 iteration += 1
0c950e3323ee cvs is going to be a module again
Skip Montanaro <skip@pobox.com>
parents:
diff changeset
302 for line in data[start:end]:
0c950e3323ee cvs is going to be a module again
Skip Montanaro <skip@pobox.com>
parents:
diff changeset
303 for char in ascii:
28828
b37af21b77be rework Sniffer api significantly
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parents: 28825
diff changeset
304 metaFrequency = charFrequency.get(char, {})
28804
0c950e3323ee cvs is going to be a module again
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parents:
diff changeset
305 # must count even if frequency is 0
36146
22dbf5818b0b Fix for problem with Sniffer class. If your delimiter is whitespace and the
Skip Montanaro <skip@pobox.com>
parents: 34406
diff changeset
306 freq = line.count(char)
28804
0c950e3323ee cvs is going to be a module again
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parents:
diff changeset
307 # value is the mode
28828
b37af21b77be rework Sniffer api significantly
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parents: 28825
diff changeset
308 metaFrequency[freq] = metaFrequency.get(freq, 0) + 1
b37af21b77be rework Sniffer api significantly
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parents: 28825
diff changeset
309 charFrequency[char] = metaFrequency
28804
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parents:
diff changeset
310
0c950e3323ee cvs is going to be a module again
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parents:
diff changeset
311 for char in charFrequency.keys():
40809
f340cb045bf9 - PEP 3106: dict.iterkeys(), .iteritems(), .itervalues() are now gone;
Guido van Rossum <guido@python.org>
parents: 40644
diff changeset
312 items = list(charFrequency[char].items())
28804
0c950e3323ee cvs is going to be a module again
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parents:
diff changeset
313 if len(items) == 1 and items[0][0] == 0:
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Skip Montanaro <skip@pobox.com>
parents:
diff changeset
314 continue
0c950e3323ee cvs is going to be a module again
Skip Montanaro <skip@pobox.com>
parents:
diff changeset
315 # get the mode of the frequencies
0c950e3323ee cvs is going to be a module again
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parents:
diff changeset
316 if len(items) > 1:
39627
e86c0b29b4a2 Kill reduce(). A coproduction of John Reese, Jacques Frechet, and Alex M.
Guido van Rossum <guido@python.org>
parents: 36157
diff changeset
317 modes[char] = max(items, key=lambda x: x[1])
28804
0c950e3323ee cvs is going to be a module again
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parents:
diff changeset
318 # adjust the mode - subtract the sum of all
0c950e3323ee cvs is going to be a module again
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parents:
diff changeset
319 # other frequencies
0c950e3323ee cvs is going to be a module again
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parents:
diff changeset
320 items.remove(modes[char])
0c950e3323ee cvs is going to be a module again
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parents:
diff changeset
321 modes[char] = (modes[char][0], modes[char][1]
39627
e86c0b29b4a2 Kill reduce(). A coproduction of John Reese, Jacques Frechet, and Alex M.
Guido van Rossum <guido@python.org>
parents: 36157
diff changeset
322 - sum(item[1] for item in items))
28804
0c950e3323ee cvs is going to be a module again
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parents:
diff changeset
323 else:
0c950e3323ee cvs is going to be a module again
Skip Montanaro <skip@pobox.com>
parents:
diff changeset
324 modes[char] = items[0]
0c950e3323ee cvs is going to be a module again
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parents:
diff changeset
325
0c950e3323ee cvs is going to be a module again
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parents:
diff changeset
326 # build a list of possible delimiters
0c950e3323ee cvs is going to be a module again
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parents:
diff changeset
327 modeList = modes.items()
0c950e3323ee cvs is going to be a module again
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parents:
diff changeset
328 total = float(chunkLength * iteration)
0c950e3323ee cvs is going to be a module again
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parents:
diff changeset
329 # (rows of consistent data) / (number of rows) = 100%
0c950e3323ee cvs is going to be a module again
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parents:
diff changeset
330 consistency = 1.0
0c950e3323ee cvs is going to be a module again
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parents:
diff changeset
331 # minimum consistency threshold
0c950e3323ee cvs is going to be a module again
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parents:
diff changeset
332 threshold = 0.9
0c950e3323ee cvs is going to be a module again
Skip Montanaro <skip@pobox.com>
parents:
diff changeset
333 while len(delims) == 0 and consistency >= threshold:
0c950e3323ee cvs is going to be a module again
Skip Montanaro <skip@pobox.com>
parents:
diff changeset
334 for k, v in modeList:
0c950e3323ee cvs is going to be a module again
Skip Montanaro <skip@pobox.com>
parents:
diff changeset
335 if v[0] > 0 and v[1] > 0:
29169
434ef174f478 * Correct Sniffer doc to correspond to the implementation.
Skip Montanaro <skip@pobox.com>
parents: 28828
diff changeset
336 if ((v[1]/total) >= consistency and
434ef174f478 * Correct Sniffer doc to correspond to the implementation.
Skip Montanaro <skip@pobox.com>
parents: 28828
diff changeset
337 (delimiters is None or k in delimiters)):
28804
0c950e3323ee cvs is going to be a module again
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parents:
diff changeset
338 delims[k] = v
0c950e3323ee cvs is going to be a module again
Skip Montanaro <skip@pobox.com>
parents:
diff changeset
339 consistency -= 0.01
0c950e3323ee cvs is going to be a module again
Skip Montanaro <skip@pobox.com>
parents:
diff changeset
340
0c950e3323ee cvs is going to be a module again
Skip Montanaro <skip@pobox.com>
parents:
diff changeset
341 if len(delims) == 1:
40809
f340cb045bf9 - PEP 3106: dict.iterkeys(), .iteritems(), .itervalues() are now gone;
Guido van Rossum <guido@python.org>
parents: 40644
diff changeset
342 delim = list(delims.keys())[0]
28804
0c950e3323ee cvs is going to be a module again
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parents:
diff changeset
343 skipinitialspace = (data[0].count(delim) ==
0c950e3323ee cvs is going to be a module again
Skip Montanaro <skip@pobox.com>
parents:
diff changeset
344 data[0].count("%c " % delim))
0c950e3323ee cvs is going to be a module again
Skip Montanaro <skip@pobox.com>
parents:
diff changeset
345 return (delim, skipinitialspace)
0c950e3323ee cvs is going to be a module again
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parents:
diff changeset
346
0c950e3323ee cvs is going to be a module again
Skip Montanaro <skip@pobox.com>
parents:
diff changeset
347 # analyze another chunkLength lines
0c950e3323ee cvs is going to be a module again
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parents:
diff changeset
348 start = end
0c950e3323ee cvs is going to be a module again
Skip Montanaro <skip@pobox.com>
parents:
diff changeset
349 end += chunkLength
0c950e3323ee cvs is going to be a module again
Skip Montanaro <skip@pobox.com>
parents:
diff changeset
350
0c950e3323ee cvs is going to be a module again
Skip Montanaro <skip@pobox.com>
parents:
diff changeset
351 if not delims:
0c950e3323ee cvs is going to be a module again
Skip Montanaro <skip@pobox.com>
parents:
diff changeset
352 return ('', 0)
0c950e3323ee cvs is going to be a module again
Skip Montanaro <skip@pobox.com>
parents:
diff changeset
353
0c950e3323ee cvs is going to be a module again
Skip Montanaro <skip@pobox.com>
parents:
diff changeset
354 # if there's more than one, fall back to a 'preferred' list
0c950e3323ee cvs is going to be a module again
Skip Montanaro <skip@pobox.com>
parents:
diff changeset
355 if len(delims) > 1:
0c950e3323ee cvs is going to be a module again
Skip Montanaro <skip@pobox.com>
parents:
diff changeset
356 for d in self.preferred:
0c950e3323ee cvs is going to be a module again
Skip Montanaro <skip@pobox.com>
parents:
diff changeset
357 if d in delims.keys():
0c950e3323ee cvs is going to be a module again
Skip Montanaro <skip@pobox.com>
parents:
diff changeset
358 skipinitialspace = (data[0].count(d) ==
0c950e3323ee cvs is going to be a module again
Skip Montanaro <skip@pobox.com>
parents:
diff changeset
359 data[0].count("%c " % d))
0c950e3323ee cvs is going to be a module again
Skip Montanaro <skip@pobox.com>
parents:
diff changeset
360 return (d, skipinitialspace)
0c950e3323ee cvs is going to be a module again
Skip Montanaro <skip@pobox.com>
parents:
diff changeset
361
36157
96eb2a5cfbef Fix a delimiter detection problem in sniffer. Sniffing "a|b|c\r\n" was
Skip Montanaro <skip@pobox.com>
parents: 36146
diff changeset
362 # nothing else indicates a preference, pick the character that
96eb2a5cfbef Fix a delimiter detection problem in sniffer. Sniffing "a|b|c\r\n" was
Skip Montanaro <skip@pobox.com>
parents: 36146
diff changeset
363 # dominates(?)
96eb2a5cfbef Fix a delimiter detection problem in sniffer. Sniffing "a|b|c\r\n" was
Skip Montanaro <skip@pobox.com>
parents: 36146
diff changeset
364 items = [(v,k) for (k,v) in delims.items()]
96eb2a5cfbef Fix a delimiter detection problem in sniffer. Sniffing "a|b|c\r\n" was
Skip Montanaro <skip@pobox.com>
parents: 36146
diff changeset
365 items.sort()
96eb2a5cfbef Fix a delimiter detection problem in sniffer. Sniffing "a|b|c\r\n" was
Skip Montanaro <skip@pobox.com>
parents: 36146
diff changeset
366 delim = items[-1][1]
96eb2a5cfbef Fix a delimiter detection problem in sniffer. Sniffing "a|b|c\r\n" was
Skip Montanaro <skip@pobox.com>
parents: 36146
diff changeset
367
28804
0c950e3323ee cvs is going to be a module again
Skip Montanaro <skip@pobox.com>
parents:
diff changeset
368 skipinitialspace = (data[0].count(delim) ==
0c950e3323ee cvs is going to be a module again
Skip Montanaro <skip@pobox.com>
parents:
diff changeset
369 data[0].count("%c " % delim))
0c950e3323ee cvs is going to be a module again
Skip Montanaro <skip@pobox.com>
parents:
diff changeset
370 return (delim, skipinitialspace)
0c950e3323ee cvs is going to be a module again
Skip Montanaro <skip@pobox.com>
parents:
diff changeset
371
0c950e3323ee cvs is going to be a module again
Skip Montanaro <skip@pobox.com>
parents:
diff changeset
372
28828
b37af21b77be rework Sniffer api significantly
Skip Montanaro <skip@pobox.com>
parents: 28825
diff changeset
373 def has_header(self, sample):
28804
0c950e3323ee cvs is going to be a module again
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parents:
diff changeset
374 # Creates a dictionary of types of data in each column. If any
0c950e3323ee cvs is going to be a module again
Skip Montanaro <skip@pobox.com>
parents:
diff changeset
375 # column is of a single type (say, integers), *except* for the first
0c950e3323ee cvs is going to be a module again
Skip Montanaro <skip@pobox.com>
parents:
diff changeset
376 # row, then the first row is presumed to be labels. If the type
0c950e3323ee cvs is going to be a module again
Skip Montanaro <skip@pobox.com>
parents:
diff changeset
377 # can't be determined, it is assumed to be a string in which case
0c950e3323ee cvs is going to be a module again
Skip Montanaro <skip@pobox.com>
parents:
diff changeset
378 # the length of the string is the determining factor: if all of the
0c950e3323ee cvs is going to be a module again
Skip Montanaro <skip@pobox.com>
parents:
diff changeset
379 # rows except for the first are the same length, it's a header.
0c950e3323ee cvs is going to be a module again
Skip Montanaro <skip@pobox.com>
parents:
diff changeset
380 # Finally, a 'vote' is taken at the end for each column, adding or
0c950e3323ee cvs is going to be a module again
Skip Montanaro <skip@pobox.com>
parents:
diff changeset
381 # subtracting from the likelihood of the first row being a header.
0c950e3323ee cvs is going to be a module again
Skip Montanaro <skip@pobox.com>
parents:
diff changeset
382
28828
b37af21b77be rework Sniffer api significantly
Skip Montanaro <skip@pobox.com>
parents: 28825
diff changeset
383 rdr = reader(StringIO(sample), self.sniff(sample))
28804
0c950e3323ee cvs is going to be a module again
Skip Montanaro <skip@pobox.com>
parents:
diff changeset
384
41501
0c5019afc55b PEP 3114: rename .next() to .__next__() and add next() builtin.
Georg Brandl <georg@python.org>
parents: 40809
diff changeset
385 header = next(rdr) # assume first row is header
28804
0c950e3323ee cvs is going to be a module again
Skip Montanaro <skip@pobox.com>
parents:
diff changeset
386
0c950e3323ee cvs is going to be a module again
Skip Montanaro <skip@pobox.com>
parents:
diff changeset
387 columns = len(header)
0c950e3323ee cvs is going to be a module again
Skip Montanaro <skip@pobox.com>
parents:
diff changeset
388 columnTypes = {}
0c950e3323ee cvs is going to be a module again
Skip Montanaro <skip@pobox.com>
parents:
diff changeset
389 for i in range(columns): columnTypes[i] = None
0c950e3323ee cvs is going to be a module again
Skip Montanaro <skip@pobox.com>
parents:
diff changeset
390
0c950e3323ee cvs is going to be a module again
Skip Montanaro <skip@pobox.com>
parents:
diff changeset
391 checked = 0
28828
b37af21b77be rework Sniffer api significantly
Skip Montanaro <skip@pobox.com>
parents: 28825
diff changeset
392 for row in rdr:
28804
0c950e3323ee cvs is going to be a module again
Skip Montanaro <skip@pobox.com>
parents:
diff changeset
393 # arbitrary number of rows to check, to keep it sane
0c950e3323ee cvs is going to be a module again
Skip Montanaro <skip@pobox.com>
parents:
diff changeset
394 if checked > 20:
0c950e3323ee cvs is going to be a module again
Skip Montanaro <skip@pobox.com>
parents:
diff changeset
395 break
0c950e3323ee cvs is going to be a module again
Skip Montanaro <skip@pobox.com>
parents:
diff changeset
396 checked += 1
0c950e3323ee cvs is going to be a module again
Skip Montanaro <skip@pobox.com>
parents:
diff changeset
397
0c950e3323ee cvs is going to be a module again
Skip Montanaro <skip@pobox.com>
parents:
diff changeset
398 if len(row) != columns:
0c950e3323ee cvs is going to be a module again
Skip Montanaro <skip@pobox.com>
parents:
diff changeset
399 continue # skip rows that have irregular number of columns
0c950e3323ee cvs is going to be a module again
Skip Montanaro <skip@pobox.com>
parents:
diff changeset
400
40809
f340cb045bf9 - PEP 3106: dict.iterkeys(), .iteritems(), .itervalues() are now gone;
Guido van Rossum <guido@python.org>
parents: 40644
diff changeset
401 for col in list(columnTypes.keys()):
29411
bac2c0e7c20a SF Patch #744104: Remove eval() from csv
Raymond Hettinger <python@rcn.com>
parents: 29169
diff changeset
402
46548
85d4671565c8 Obvious simplification, now that "long" has disappeared.
Amaury Forgeot d'Arc <amauryfa@gmail.com>
parents: 45996
diff changeset
403 for thisType in [int, float, complex]:
28804
0c950e3323ee cvs is going to be a module again
Skip Montanaro <skip@pobox.com>
parents:
diff changeset
404 try:
29411
bac2c0e7c20a SF Patch #744104: Remove eval() from csv
Raymond Hettinger <python@rcn.com>
parents: 29169
diff changeset
405 thisType(row[col])
bac2c0e7c20a SF Patch #744104: Remove eval() from csv
Raymond Hettinger <python@rcn.com>
parents: 29169
diff changeset
406 break
29420
f87fcd0870bf The multiple exception catch should be in a tuple.
Raymond Hettinger <python@rcn.com>
parents: 29411
diff changeset
407 except (ValueError, OverflowError):
29411
bac2c0e7c20a SF Patch #744104: Remove eval() from csv
Raymond Hettinger <python@rcn.com>
parents: 29169
diff changeset
408 pass
bac2c0e7c20a SF Patch #744104: Remove eval() from csv
Raymond Hettinger <python@rcn.com>
parents: 29169
diff changeset
409 else:
28804
0c950e3323ee cvs is going to be a module again
Skip Montanaro <skip@pobox.com>
parents:
diff changeset
410 # fallback to length of string
0c950e3323ee cvs is going to be a module again
Skip Montanaro <skip@pobox.com>
parents:
diff changeset
411 thisType = len(row[col])
0c950e3323ee cvs is going to be a module again
Skip Montanaro <skip@pobox.com>
parents:
diff changeset
412
0c950e3323ee cvs is going to be a module again
Skip Montanaro <skip@pobox.com>
parents:
diff changeset
413 if thisType != columnTypes[col]:
0c950e3323ee cvs is going to be a module again
Skip Montanaro <skip@pobox.com>
parents:
diff changeset
414 if columnTypes[col] is None: # add new column type
0c950e3323ee cvs is going to be a module again
Skip Montanaro <skip@pobox.com>
parents:
diff changeset
415 columnTypes[col] = thisType
0c950e3323ee cvs is going to be a module again
Skip Montanaro <skip@pobox.com>
parents:
diff changeset
416 else:
0c950e3323ee cvs is going to be a module again
Skip Montanaro <skip@pobox.com>
parents:
diff changeset
417 # type is inconsistent, remove column from
0c950e3323ee cvs is going to be a module again
Skip Montanaro <skip@pobox.com>
parents:
diff changeset
418 # consideration
0c950e3323ee cvs is going to be a module again
Skip Montanaro <skip@pobox.com>
parents:
diff changeset
419 del columnTypes[col]
0c950e3323ee cvs is going to be a module again
Skip Montanaro <skip@pobox.com>
parents:
diff changeset
420
0c950e3323ee cvs is going to be a module again
Skip Montanaro <skip@pobox.com>
parents:
diff changeset
421 # finally, compare results against first row and "vote"
0c950e3323ee cvs is going to be a module again
Skip Montanaro <skip@pobox.com>
parents:
diff changeset
422 # on whether it's a header
0c950e3323ee cvs is going to be a module again
Skip Montanaro <skip@pobox.com>
parents:
diff changeset
423 hasHeader = 0
0c950e3323ee cvs is going to be a module again
Skip Montanaro <skip@pobox.com>
parents:
diff changeset
424 for col, colType in columnTypes.items():
0c950e3323ee cvs is going to be a module again
Skip Montanaro <skip@pobox.com>
parents:
diff changeset
425 if type(colType) == type(0): # it's a length
0c950e3323ee cvs is going to be a module again
Skip Montanaro <skip@pobox.com>
parents:
diff changeset
426 if len(header[col]) != colType:
0c950e3323ee cvs is going to be a module again
Skip Montanaro <skip@pobox.com>
parents:
diff changeset
427 hasHeader += 1
0c950e3323ee cvs is going to be a module again
Skip Montanaro <skip@pobox.com>
parents:
diff changeset
428 else:
0c950e3323ee cvs is going to be a module again
Skip Montanaro <skip@pobox.com>
parents:
diff changeset
429 hasHeader -= 1
0c950e3323ee cvs is going to be a module again
Skip Montanaro <skip@pobox.com>
parents:
diff changeset
430 else: # attempt typecast
0c950e3323ee cvs is going to be a module again
Skip Montanaro <skip@pobox.com>
parents:
diff changeset
431 try:
29411
bac2c0e7c20a SF Patch #744104: Remove eval() from csv
Raymond Hettinger <python@rcn.com>
parents: 29169
diff changeset
432 colType(header[col])
29422
cf8ae3b0dcdc One more multiple exception catch should be in a tuple.
Raymond Hettinger <python@rcn.com>
parents: 29420
diff changeset
433 except (ValueError, TypeError):
28804
0c950e3323ee cvs is going to be a module again
Skip Montanaro <skip@pobox.com>
parents:
diff changeset
434 hasHeader += 1
0c950e3323ee cvs is going to be a module again
Skip Montanaro <skip@pobox.com>
parents:
diff changeset
435 else:
0c950e3323ee cvs is going to be a module again
Skip Montanaro <skip@pobox.com>
parents:
diff changeset
436 hasHeader -= 1
0c950e3323ee cvs is going to be a module again
Skip Montanaro <skip@pobox.com>
parents:
diff changeset
437
0c950e3323ee cvs is going to be a module again
Skip Montanaro <skip@pobox.com>
parents:
diff changeset
438 return hasHeader > 0