python numpy和list查询其中某个数的个数及定位方法

list_a = [2 for x in range(5)]
print(list_a)
a_count = list_a.count(2)
print(a_count)

[2, 2, 2, 2, 2]

#!/usr/bin/python

aList = [123, 'xyz', 'zara', 'abc'];

print "Index for xyz : ", aList.index( 'xyz' ) ;
print "Index for zara : ", aList.index( 'zara' ) ;

Index for xyz : 1
Index for zara : 2

import numpy as np

a = np.ones((4, 5))
print(a)
print(np.sum(a == 1))

[[ 1. 1. 1. 1. 1.]
 [ 1. 1. 1. 1. 1.]
 [ 1. 1. 1. 1. 1.]
 [ 1. 1. 1. 1. 1.]]
20

a = np.ones((4, 5))
a[1:3,1:3] = 4
print(a)
print(np.sum(a == 1))
print(np.where(a == 4))

[[ 1. 1. 1. 1. 1.]
 [ 1. 4. 4. 1. 1.]
 [ 1. 4. 4. 1. 1.]
 [ 1. 1. 1. 1. 1.]]
16
(array([1, 1, 2, 2]), array([1, 2, 1, 2]))