pandas.api.extensions.ExtensionArray.take
-
ExtensionArray.take(indices, allow_fill=False, fill_value=None)
[source] -
Take elements from an array.
Parameters: indices : sequence of integers
Indices to be taken.
allow_fill : bool, default False
How to handle negative values in
indices
.- False: negative values in
indices
indicate positional indices from the right (the default). This is similar tonumpy.take()
. - True: negative values in
indices
indicate missing values. These values are set tofill_value
. Any other other negative values raise aValueError
.
fill_value : any, optional
Fill value to use for NA-indices when
allow_fill
is True. This may beNone
, in which case the default NA value for the type,self.dtype.na_value
, is used.For many ExtensionArrays, there will be two representations of
fill_value
: a user-facing “boxed” scalar, and a low-level physical NA value.fill_value
should be the user-facing version, and the implementation should handle translating that to the physical version for processing the take if nescessary.Returns: - ExtensionArray
Raises: IndexError
When the indices are out of bounds for the array.
ValueError
When
indices
contains negative values other than-1
andallow_fill
is True.See also
numpy.take
,pandas.api.extensions.take
Notes
ExtensionArray.take is called by
Series.__getitem__
,.loc
,iloc
, whenindices
is a sequence of values. Additionally, it’s called bySeries.reindex()
, or any other method that causes realignemnt, with afill_value
.Examples
Here’s an example implementation, which relies on casting the extension array to object dtype. This uses the helper method
pandas.api.extensions.take()
.def take(self, indices, allow_fill=False, fill_value=None): from pandas.core.algorithms import take # If the ExtensionArray is backed by an ndarray, then # just pass that here instead of coercing to object. data = self.astype(object) if allow_fill and fill_value is None: fill_value = self.dtype.na_value # fill value should always be translated from the scalar # type for the array, to the physical storage type for # the data, before passing to take. result = take(data, indices, fill_value=fill_value, allow_fill=allow_fill) return self._from_sequence(result)
- False: negative values in
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https://pandas.pydata.org/pandas-docs/version/0.23.4/generated/pandas.api.extensions.ExtensionArray.take.html