数据拷贝

r2 = r[:3,:3]
r2

array([[ 0,  1,  2],
       [ 6,  7,  8],
       [12, 13, 14]])

r2[:] = 0
r2

array([[0, 0, 0],
       [0, 0, 0],
       [0, 0, 0]])

此时r=

array([[ 0,  0,  0,  3,  4,  5],
       [ 0,  0,  0,  9, 10, 11],
       [ 0,  0,  0, 15, 16, 17],
       [18, 19, 20, 21, 22, 23],
       [24, 25, 26, 27, 28, 29],
       [30, 30, 30, 30, 30, 30]])

r_copy = r.copy()
r_copy

array([[ 0,  0,  0,  3,  4,  5],
       [ 0,  0,  0,  9, 10, 11],
       [ 0,  0,  0, 15, 16, 17],
       [18, 19, 20, 21, 22, 23],
       [24, 25, 26, 27, 28, 29],
       [30, 30, 30, 30, 30, 30]])

r_copy[:] = 10
print(r_copy, '
')
print(r)

[[10 10 10 10 10 10]
 [10 10 10 10 10 10]
 [10 10 10 10 10 10]
 [10 10 10 10 10 10]
 [10 10 10 10 10 10]
 [10 10 10 10 10 10]] 

[[ 0  0  0  3  4  5]
 [ 0  0  0  9 10 11]
 [ 0  0  0 15 16 17]
 [18 19 20 21 22 23]
 [24 25 26 27 28 29]
 [30 30 30 30 30 30]]

test = np.random.randint(0, 10, (4,3))
test

array([[0, 7, 9],
       [9, 2, 3],
       [7, 5, 9],
       [4, 8, 4]])

for row in test:
    print(row)

[0 7 9]
[9 2 3]
[7 5 9]
[4 8 4]

for i in range(len(test)):
    print(test[i])

[0 7 9]
[9 2 3]
[7 5 9]
[4 8 4]

for i, row in enumerate(test):
    print('row', i, 'is', row)

row 0 is [0 7 9]
row 1 is [9 2 3]
row 2 is [7 5 9]
row 3 is [4 8 4]

test2 = test**2
test2

array([[ 0, 49, 81],
       [81,  4,  9],
       [49, 25, 81],
       [16, 64, 16]])

for i, j in zip(test, test2):
    print(i,'+',j,'=',i+j)

[0 7 9] + [ 0 49 81] = [ 0 56 90]
[9 2 3] + [81  4  9] = [90  6 12]
[7 5 9] + [49 25 81] = [56 30 90]
[4 8 4] + [16 64 16] = [20 72 20]