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Diffstat (limited to 'Doc/library/csv.rst')
| -rw-r--r-- | Doc/library/csv.rst | 71 |
1 files changed, 37 insertions, 34 deletions
diff --git a/Doc/library/csv.rst b/Doc/library/csv.rst index e82c376..ccc9dc6 100644 --- a/Doc/library/csv.rst +++ b/Doc/library/csv.rst @@ -142,40 +142,43 @@ The :mod:`csv` module defines the following functions: The :mod:`csv` module defines the following classes: -.. class:: DictReader(csvfile, fieldnames=None, restkey=None, restval=None, dialect='excel', *args, **kwds) - - Create an object which operates like a regular reader but maps the information - read into a dict whose keys are given by the optional *fieldnames* parameter. - The *fieldnames* parameter is a :mod:`sequence <collections.abc>` whose elements - are associated with the fields of the input data in order. These elements - become the keys of the resulting dictionary. - If the *fieldnames* parameter is omitted, the values in the first row of the - *csvfile* will be used as the fieldnames. If the row read has more fields - than the fieldnames sequence, the remaining data is added as a sequence - keyed by the value of *restkey*. If the row read has fewer fields than the - fieldnames sequence, the remaining keys take the value of the optional - *restval* parameter. Any other optional or keyword arguments are passed to - the underlying :class:`reader` instance. - - -.. class:: DictWriter(csvfile, fieldnames, restval='', extrasaction='raise', dialect='excel', *args, **kwds) - - Create an object which operates like a regular writer but maps dictionaries onto - output rows. The *fieldnames* parameter is a :mod:`sequence - <collections.abc>` of keys that identify the order in which values in - the dictionary passed to the :meth:`writerow` method are written to the - *csvfile*. The optional *restval* parameter specifies the value to be written - if the dictionary is missing a key in *fieldnames*. If the dictionary passed to - the :meth:`writerow` method contains a key not found in *fieldnames*, the - optional *extrasaction* parameter indicates what action to take. If it is set - to ``'raise'`` a :exc:`ValueError` is raised. If it is set to ``'ignore'``, - extra values in the dictionary are ignored. Any other optional or keyword - arguments are passed to the underlying :class:`writer` instance. - - Note that unlike the :class:`DictReader` class, the *fieldnames* parameter of - the :class:`DictWriter` is not optional. Since Python's :class:`dict` objects - are not ordered, there is not enough information available to deduce the order - in which the row should be written to the *csvfile*. +.. class:: DictReader(csvfile, fieldnames=None, restkey=None, restval=None, \ + dialect='excel', *args, **kwds) + + Create an object which operates like a regular reader but maps the + information read into a dict whose keys are given by the optional + *fieldnames* parameter. The *fieldnames* parameter is a :mod:`sequence + <collections.abc>` whose elements are associated with the fields of the + input data in order. These elements become the keys of the resulting + dictionary. If the *fieldnames* parameter is omitted, the values in the + first row of the *csvfile* will be used as the fieldnames. If the row read + has more fields than the fieldnames sequence, the remaining data is added as + a sequence keyed by the value of *restkey*. If the row read has fewer + fields than the fieldnames sequence, the remaining keys take the value of + the optional *restval* parameter. Any other optional or keyword arguments + are passed to the underlying :class:`reader` instance. + + +.. class:: DictWriter(csvfile, fieldnames, restval='', extrasaction='raise', \ + dialect='excel', *args, **kwds) + + Create an object which operates like a regular writer but maps dictionaries + onto output rows. The *fieldnames* parameter is a :mod:`sequence + <collections.abc>` of keys that identify the order in which values in the + dictionary passed to the :meth:`writerow` method are written to the + *csvfile*. The optional *restval* parameter specifies the value to be + written if the dictionary is missing a key in *fieldnames*. If the + dictionary passed to the :meth:`writerow` method contains a key not found in + *fieldnames*, the optional *extrasaction* parameter indicates what action to + take. If it is set to ``'raise'`` a :exc:`ValueError` is raised. If it is + set to ``'ignore'``, extra values in the dictionary are ignored. Any other + optional or keyword arguments are passed to the underlying :class:`writer` + instance. + + Note that unlike the :class:`DictReader` class, the *fieldnames* parameter + of the :class:`DictWriter` is not optional. Since Python's :class:`dict` + objects are not ordered, there is not enough information available to deduce + the order in which the row should be written to the *csvfile*. .. class:: Dialect |