Indexing routines¶
See also
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, either from x or y, depending on condition. |
indices (dimensions[, dtype]) |
Return an array representing the indices of a grid. |
ix_ (*args) |
Construct an open mesh from multiple sequences. |
ogrid |
nd_grid 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, dims[, 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. |
choose (a, choices[, out, mode]) |
Construct an array from an index array and a set 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. |
lib.stride_tricks.as_strided (x[, shape, …]) |
Create a view into the array with the given shape and strides. |
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. |
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 |
Efficient multi-dimensional iterator object to iterate over arrays. |
ndenumerate (arr) |
Multidimensional index iterator. |
ndindex (*shape) |
An N-dimensional iterator object to index arrays. |
flatiter |
Flat iterator object to iterate over arrays. |
lib.Arrayterator (var[, buf_size]) |
Buffered iterator for big arrays. |