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flip

Reverse the order of elements along the given axis or axes. 
function flip(m: ArrayLike, axis?: number | number[]): NDArray
NameTypeDefaultDescription
mArrayLike—Input array.
axisnumber | number[]undefinedAxis or axes along which to flip. If undefined, flips along all axes.
Returns: NDArray — A new array with elements reversed along the specified axis. 
import * as np from 'numpy-ts';

const a = np.array([[1, 2, 3], [4, 5, 6]]);

// Flip all axes
const b = np.flip(a);
console.log(b.toArray());
// [[6, 5, 4],
//  [3, 2, 1]]

// Flip along axis 0 (reverse rows)
const c = np.flip(a, 0);
console.log(c.toArray());
// [[4, 5, 6],
//  [1, 2, 3]]

// Flip along axis 1 (reverse columns)
const d = np.flip(a, 1);
console.log(d.toArray());
// [[3, 2, 1],
//  [6, 5, 4]]

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fliplr

Flip an array left to right (reverse along axis 1). The input must have at least 2 dimensions. 
function fliplr(m: ArrayLike): NDArray
NameTypeDefaultDescription
mArrayLike—Input array with at least 2 dimensions.
Returns: NDArray — Array with columns reversed. Equivalent to flip(m, 1). 
import * as np from 'numpy-ts';

const a = np.array([[1, 2, 3], [4, 5, 6]]);

const b = np.fliplr(a);
console.log(b.toArray());
// [[3, 2, 1],
//  [6, 5, 4]]

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flipud

Flip an array up to down (reverse along axis 0). 
function flipud(m: ArrayLike): NDArray
NameTypeDefaultDescription
mArrayLike—Input array.
Returns: NDArray — Array with rows reversed. Equivalent to flip(m, 0). 
import * as np from 'numpy-ts';

const a = np.array([[1, 2], [3, 4], [5, 6]]);

const b = np.flipud(a);
console.log(b.toArray());
// [[5, 6],
//  [3, 4],
//  [1, 2]]

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rot90

Rotate an array by 90 degrees in the plane specified by the given axes. The input must have at least 2 dimensions. 
function rot90(
  m: ArrayLike,
  k?: number,
  axes?: [number, number]
): NDArray
NameTypeDefaultDescription
mArrayLike—Input array with at least 2 dimensions.
knumber1Number of 90-degree counter-clockwise rotations. Negative values rotate clockwise.
axes[number, number][0, 1]The plane in which to rotate, defined by two axes.
Returns: NDArray — The rotated array. 
import * as np from 'numpy-ts';

const a = np.array([[1, 2], [3, 4]]);

// Rotate 90 degrees counter-clockwise (default)
const b = np.rot90(a);
console.log(b.toArray());
// [[2, 4],
//  [1, 3]]

// Rotate 180 degrees
const c = np.rot90(a, 2);
console.log(c.toArray());
// [[4, 3],
//  [2, 1]]

// Rotate 90 degrees clockwise (k = -1 or k = 3)
const d = np.rot90(a, -1);
console.log(d.toArray());
// [[3, 1],
//  [4, 2]]

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roll

Roll array elements along a given axis. Elements that roll past the last position wrap around to the first. 
function roll(
  a: ArrayLike,
  shift: number | number[],
  axis?: number | number[]
): NDArray
NameTypeDefaultDescription
aArrayLike—Input array.
shiftnumber | number[]—Number of positions to shift. Positive shifts right, negative shifts left. If an array, each value corresponds to an axis.
axisnumber | number[]undefinedAxis or axes along which to roll. If undefined, the array is flattened, rolled, then reshaped.
Returns: NDArray — Array with elements rolled. 
import * as np from 'numpy-ts';

const a = np.array([0, 1, 2, 3, 4]);

// Roll forward by 2
const b = np.roll(a, 2);
console.log(b.toArray());  // [3, 4, 0, 1, 2]

// Roll backward by 1
const c = np.roll(a, -1);
console.log(c.toArray());  // [1, 2, 3, 4, 0]

// Roll along a specific axis
const d = np.array([[1, 2, 3], [4, 5, 6]]);
const e = np.roll(d, 1, 1);
console.log(e.toArray());
// [[3, 1, 2],
//  [6, 4, 5]]

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delete_

Remove elements from an array along an axis. Returns a new array (copy). Exported as both delete_ and delete. 
function delete_(
  arr: ArrayLike,
  obj: number | number[],
  axis?: number
): NDArray
NameTypeDefaultDescription
arrArrayLike—Input array.
objnumber | number[]—Index or indices of elements to remove. Negative indices are supported.
axisnumberundefinedAxis along which to delete. If undefined, the array is flattened first.
Returns: NDArray — A copy of a with the specified elements removed. 
import * as np from 'numpy-ts';

const a = np.array([[1, 2, 3], [4, 5, 6], [7, 8, 9]]);

// Delete row 1
const b = np.delete_(a, 1, 0);
console.log(b.toArray());
// [[1, 2, 3],
//  [7, 8, 9]]

// Delete column 0 and column 2
const c = np.delete_(a, [0, 2], 1);
console.log(c.toArray());
// [[2],
//  [5],
//  [8]]

// Without axis: flatten then delete
const d = np.delete_(a, [0, 4]);
console.log(d.toArray());  // [2, 3, 4, 6, 7, 8, 9]

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atleast_1d

Convert inputs to arrays with at least 1 dimension. Scalar (0-D) inputs become 1-D arrays of length 1. Higher-dimensional inputs are returned unchanged. 
function atleast_1d(...arrays: ArrayLike[]): NDArray | NDArray[]
NameTypeDefaultDescription
...arraysArrayLike[]—One or more input arrays.
Returns: NDArray | NDArray[] — A single array if one input was given, or a list of arrays if multiple inputs were given. Each output has ndim >= 1. 
import * as np from 'numpy-ts';

// Single scalar input
const a = np.atleast_1d(np.array([42]));
console.log(a.shape);  // [1]

// Multiple inputs
const [b, c] = np.atleast_1d(
  np.array([1]),
  np.array([1, 2, 3])
) as np.NDArray[];
console.log(b.shape);  // [1]
console.log(c.shape);  // [3]

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atleast_2d

Convert inputs to arrays with at least 2 dimensions. 0-D inputs become (1, 1), 1-D inputs of length N become (1, N). Higher-dimensional inputs are returned unchanged. 
function atleast_2d(...arrays: ArrayLike[]): NDArray | NDArray[]
NameTypeDefaultDescription
...arraysArrayLike[]—One or more input arrays.
Returns: NDArray | NDArray[] — A single array if one input was given, or a list of arrays. Each output has ndim >= 2. 
import * as np from 'numpy-ts';

const a = np.array([1, 2, 3]);

const b = np.atleast_2d(a) as np.NDArray;
console.log(b.shape);     // [1, 3]
console.log(b.toArray());  // [[1, 2, 3]]

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atleast_3d

Convert inputs to arrays with at least 3 dimensions. 0-D inputs become (1, 1, 1), 1-D inputs of length N become (1, N, 1), and 2-D inputs of shape (M, N) become (M, N, 1). Higher-dimensional inputs are returned unchanged. 
function atleast_3d(...arrays: ArrayLike[]): NDArray | NDArray[]
NameTypeDefaultDescription
...arraysArrayLike[]—One or more input arrays.
Returns: NDArray | NDArray[] — A single array if one input was given, or a list of arrays. Each output has ndim >= 3. 
import * as np from 'numpy-ts';

const a = np.array([[1, 2], [3, 4]]);

const b = np.atleast_3d(a) as np.NDArray;
console.log(b.shape);  // [2, 2, 1]

const c = np.array([1, 2, 3]);
const d = np.atleast_3d(c) as np.NDArray;
console.log(d.shape);  // [1, 3, 1]