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Pandas Series: where() function

Series-where() function

The where() function is used to replace values where the condition is False.

Syntax:

Series.where(self, cond, other=nan, inplace=False, axis=None, level=None, errors='raise', try_cast=False)
Pandas Series where image
Name Description Type/Default Value Required / Optional
cond Where cond is True, keep the original value. Where False, replace with corresponding value from other. If cond is callable, it is computed on the Series/DataFrame and should return boolean Series/DataFrame or array. The callable must not change input Series/DataFrame (though pandas doesn’t check it). boolean Series/DataFrame, array-like, or callable Required
other Entries where cond is False are replaced with corresponding value from other. If other is callable, it is computed on the Series/DataFrame and should return scalar or Series/DataFrame. The callable must not change input Series/DataFrame (though pandas doesn’t check it). scalar, Series/DataFrame, or callable Required
inplace Whether to perform the operation in place on the data. bool
Default Value: False
Required
axis Alignment axis if needed. int
Default Value: None
Required
level Alignment level if needed. int
Default Value: None
Required
errors Note that currently this parameter won’t affect the results and will always coerce to a suitable dtype.
  • ‘raise’ : allow exceptions to be raised.
  • ‘ignore’ : suppress exceptions. On error return original object.
str, {‘raise’, ‘ignore’}
Default Value: ‘raise’
Required
try_cast Try to cast the result back to the input type (if possible). bool
Default Value: False
Required

Returns: Same type as caller

Notes: The where method is an application of the if-then idiom. For each element in the calling DataFrame, if cond is True the element is used; otherwise the corresponding element from the DataFrame other is used.

Example:


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