numpy.tril#

numpy.tril(m,k=0)[source]#

Lower triangle of an array.

Return a copy of an array with elements above thek-th diagonal zeroed.For arrays withndim exceeding 2,tril will apply to the final twoaxes.

Parameters:

marray_like, shape (…, M, N)

Input array.

kint, optional

Diagonal above which to zero elements.k = 0 (the default) is themain diagonal,k < 0 is below it andk > 0 is above.

Returns:

trilndarray, shape (…, M, N)

Lower triangle ofm, of same shape and data-type asm.

See also

triu

same thing, only for the upper triangle

Examples

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>>>importnumpyasnp>>>np.tril([[1,2,3],[4,5,6],[7,8,9],[10,11,12]],-1)array([[ 0,  0,  0],       [ 4,  0,  0],       [ 7,  8,  0],       [10, 11, 12]])

>>>np.tril(np.arange(3*4*5).reshape(3,4,5))array([[[ 0,  0,  0,  0,  0],        [ 5,  6,  0,  0,  0],        [10, 11, 12,  0,  0],        [15, 16, 17, 18,  0]],       [[20,  0,  0,  0,  0],        [25, 26,  0,  0,  0],        [30, 31, 32,  0,  0],        [35, 36, 37, 38,  0]],       [[40,  0,  0,  0,  0],        [45, 46,  0,  0,  0],        [50, 51, 52,  0,  0],        [55, 56, 57, 58,  0]]])

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