Indexing routines#

See also

Indexing on ndarrays

Generating index arrays#

`c_`	Translates slice objects to concatenation along the second axis.
`r_`	Translates slice objects to concatenation along the first axis.
`s_`	A nicer way to build up index tuples for arrays.
`nonzero`(a)	Return the indices of the elements that are non-zero.
`where`(condition, [x, y], /)	Return elements chosen from x or y depending on condition.
`indices`(dimensions[, dtype, sparse])	Return an array representing the indices of a grid.
`ix_`(*args)	Construct an open mesh from multiple sequences.
`ogrid`	An instance which returns an open multi-dimensional "meshgrid".
`ravel_multi_index`(multi_index, dims[, mode, ...])	Converts a tuple of index arrays into an array of flat indices, applying boundary modes to the multi-index.
`unravel_index`(indices, shape[, order])	Converts a flat index or array of flat indices into a tuple of coordinate arrays.
`diag_indices`(n[, ndim])	Return the indices to access the main diagonal of an array.
`diag_indices_from`(arr)	Return the indices to access the main diagonal of an n-dimensional array.
`mask_indices`(n, mask_func[, k])	Return the indices to access (n, n) arrays, given a masking function.
`tril_indices`(n[, k, m])	Return the indices for the lower-triangle of an (n, m) array.
`tril_indices_from`(arr[, k])	Return the indices for the lower-triangle of arr.
`triu_indices`(n[, k, m])	Return the indices for the upper-triangle of an (n, m) array.
`triu_indices_from`(arr[, k])	Return the indices for the upper-triangle of arr.

Indexing-like operations#

`take`(a, indices[, axis, out, mode])	Take elements from an array along an axis.
`take_along_axis`(arr, indices[, axis])	Take values from the input array by matching 1d index and data slices.
`choose`(a, choices[, out, mode])	Construct an array from an index array and a list of arrays to choose from.
`compress`(condition, a[, axis, out])	Return selected slices of an array along given axis.
`diag`(v[, k])	Extract a diagonal or construct a diagonal array.
`diagonal`(a[, offset, axis1, axis2])	Return specified diagonals.
`select`(condlist, choicelist[, default])	Return an array drawn from elements in choicelist, depending on conditions.

Inserting data into arrays#

`place`(arr, mask, vals)	Change elements of an array based on conditional and input values.
`put`(a, ind, v[, mode])	Replaces specified elements of an array with given values.
`put_along_axis`(arr, indices, values, axis)	Put values into the destination array by matching 1d index and data slices.
`putmask`(a, mask, values)	Changes elements of an array based on conditional and input values.
`fill_diagonal`(a, val[, wrap])	Fill the main diagonal of the given array of any dimensionality.

Iterating over arrays#

`nditer`(op[, flags, op_flags, op_dtypes, ...])	Efficient multi-dimensional iterator object to iterate over arrays.
`ndenumerate`(arr)	Multidimensional index iterator.
`ndindex`(*shape)	An N-dimensional iterator object to index arrays.
`nested_iters`(op, axes[, flags, op_flags, ...])	Create nditers for use in nested loops
`flatiter`()	Flat iterator object to iterate over arrays.
`iterable`(y)	Check whether or not an object can be iterated over.