在Python中查找给定数组中的最小值索引

Question

I need to find the index of more than one minimum values that occur in an array. I am pretty known with np.argmin but it gives me the index of very first minimum value in a array. For example.

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

This gives me 0, instead I am expecting, 0,5,7.

Thanks!

Answer 1

This should do the trick:

a = np.array([1,2,3,4,5,1,6,1]) 
print np.where(a == a.min())

argmin doesn't return a list like you expect it to in this case.

Answer 2

Maybe

mymin = np.min(a)
min_positions = [i for i, x in enumerate(a) if x == mymin]

It will give [0,5,7].

Answer 3

I think this would be the easiest way, although it doesn't use any fancy numpy function

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

print "min_val = {0}".format(min_val)                                        

# Find all of them                                                           
min_idxs = [idx for idx, val in enumerate(a) if val == min_val]              
print "min_idxs = {0}".format(min_idxs)