如何在二维numpy数组中将每一列的最大值设为零？

Question

np.random.seed(2)
a = np.random.rand(5,3)
print(a)

result:
a = [[0.4359949  0.02592623 0.54966248] 
    [0.43532239 0.4203678  0.33033482]
    [0.20464863 0.61927097 0.29965467]
    [0.26682728 0.62113383 0.52914209]
    [0.13457995 0.51357812 0.18443987]]

轴0最大值的指标

m = a.shape[1] 
a_labels = np.argmax(a,axis=0).reshape(1,m)
print(a_labels)

result:
a_labels = [[0 3 0]]

我想使每一列的最大值为0，如下所示...。我该怎么办？

result needed:
a = [[0         0.02592623 0         ] 
    [0.43532239 0.4203678  0.33033482]
    [0.20464863 0.61927097 0.29965467]
    [0.26682728 0          0.52914209]
    [0.13457995 0.51357812 0.18443987]]