NumPy

numpy.argmin

numpy.argmin(a, axis=None, out=None)[source]

Returns the indices of the minimum values along an axis.

Parameters
aarray_like

Input array.

axisint, optional

By default, the index is into the flattened array, otherwise along the specified axis.

outarray, optional

If provided, the result will be inserted into this array. It should be of the appropriate shape and dtype.

Returns
index_arrayndarray of ints

Array of indices into the array. It has the same shape as a.shape with the dimension along axis removed.

See also

ndarray.argmin, argmax

amin

The minimum value along a given axis.

unravel_index

Convert a flat index into an index tuple.

take_along_axis

Apply np.expand_dims(index_array, axis) from argmin to an array as if by calling min.

Notes

In case of multiple occurrences of the minimum values, the indices corresponding to the first occurrence are returned.

Examples

>>> a = np.arange(6).reshape(2,3) + 10
>>> a
array([[10, 11, 12],
       [13, 14, 15]])
>>> np.argmin(a)
0
>>> np.argmin(a, axis=0)
array([0, 0, 0])
>>> np.argmin(a, axis=1)
array([0, 0])

Indices of the minimum elements of a N-dimensional array:

>>> ind = np.unravel_index(np.argmin(a, axis=None), a.shape)
>>> ind
(0, 0)
>>> a[ind]
10
>>> b = np.arange(6) + 10
>>> b[4] = 10
>>> b
array([10, 11, 12, 13, 10, 15])
>>> np.argmin(b)  # Only the first occurrence is returned.
0
>>> x = np.array([[4,2,3], [1,0,3]])
>>> index_array = np.argmin(x, axis=-1)
>>> # Same as np.min(x, axis=-1, keepdims=True)
>>> np.take_along_axis(x, np.expand_dims(index_array, axis=-1), axis=-1)
array([[2],
       [0]])
>>> # Same as np.max(x, axis=-1)
>>> np.take_along_axis(x, np.expand_dims(index_array, axis=-1), axis=-1).squeeze(axis=-1)
array([2, 0])

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