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