Indexs in Arkouda

Like Pandas, Arkouda supports Indexes. The purpose and intended functionality remains the same in Arkouda, but are configured to be based on arkouda.pdarrays.

class arkouda.Index(values, name=None, allow_list=False, max_list_size=1000)[source]

Sequence used for indexing and alignment.

The basic object storing axis labels for all DataFrame objects.

Parameters:

  • values (List, pdarray, Strings, Categorical, pandas.Categorical, pandas.Index, or Index)

  • name (str, default=None) – Name to be stored in the index.

  • False (allow_list =) – If False, list values will be converted to a pdarray. If True, list values will remain as a list, provided the data length is less than max_list_size.

:paramIf False, list values will be converted to a pdarray.

If True, list values will remain as a list, provided the data length is less than max_list_size.

Parameters:

1000 (max_list_size =) – This is the maximum allowed data length for the values to be stored as a list object.

Raises:

ValueError – Raised if allow_list=True and the size of values is > max_list_size.

See also

MultiIndex

Examples

>>> import arkouda as ak
>>> ak.Index([1, 2, 3])
Index(array([1 2 3]), dtype='int64')

>>> ak.Index(list('abc'))
Index(array(['a', 'b', 'c']), dtype='<U0')

>>> ak.Index([1, 2, 3], allow_list=True)
Index([1, 2, 3], dtype='int64')

Additionally, Multi-Indexes are supported for indexes with multiple keys.

..autoclass:: arkouda.MultiIndex

Features

Index support the majority of functionality offered by pandas.Index.

Change Dtype

arkouda.Index.set_dtype(self, dtype)

Change the data type of the index.

Currently only aku.ip_address and ak.array are supported.

arkouda.MultiIndex.set_dtype(self, dtype)

Change the data type of the index.

Currently only aku.ip_address and ak.array are supported.

ArgSort

arkouda.Index.argsort(self, ascending=True)

Return the indices that would sort the Index.

Parameters:

ascending (bool, optional) – If True (default), sort in ascending order. If False, sort in descending order.

Returns:

The indices that would sort the Index.

Return type:

array-like

arkouda.MultiIndex.argsort(self, ascending=True)

Return the indices that would sort the MultiIndex.

Parameters:

ascending (bool, default True) – If False, the result is in descending order.

Returns:

An array of indices that would sort the MultiIndex.

Return type:

pdarray

Lookup

arkouda.Index.lookup(self, key)

Check for presence of key(s) in the Index.

Parameters:

key (pdarray or scalar) – The value(s) to look up in the Index. If a scalar is provided, it will be converted to a one-element array.

Returns:

A boolean array indicating which elements of key are present in the Index.

Return type:

pdarray

Raises:

TypeError – If key is not a scalar or a pdarray.

arkouda.MultiIndex.lookup(self, key)

Perform element-wise lookup on the MultiIndex.

Parameters:

key (list or tuple) – A sequence of values, one for each level of the MultiIndex. Values may be scalars or pdarrays. If scalars, they are cast to the appropriate Arkouda array type.

Returns:

A boolean array indicating which rows in the MultiIndex match the key.

Return type:

pdarray

Raises:

TypeError – If key is not a list or tuple, or if its elements cannot be converted to pdarrays.

Concat

arkouda.Index.concat(self, other)

Concatenate this Index with another Index.

Parameters:

other (Index) – The Index to concatenate with this one.

Returns:

A new Index with values from both indices.

Return type:

Index

Raises:

TypeError – If the types of the two Index objects do not match.

arkouda.MultiIndex.concat(self, other)

Concatenate this MultiIndex with another, preserving duplicates and order.

Parameters:

other (MultiIndex) – The other MultiIndex to concatenate with.

Returns:

A new MultiIndex containing values from both inputs, preserving order.

Return type:

MultiIndex

Raises:

TypeError – If the type of other does not match.