如何在python中重写嵌套列表中某个元素的值？

因此，我试图重写列表中某个位置的元素，m。但它显示了一个错误：

M = [[3.5, 1.0, 9.2, 4.0], [0, 0, 0, 0], [3.0, 1.0, 8.0, -2.0]]
c_idx = 2
for count4 in range(len(M)):
    for count5 in range(len(M[count4])):
        if M[count4].index(M[count4][count5]) == c_idx :
            M[count4] = M[count4][ :c_idx] + [0] + M[count4][c_idx+1 : ]
        count4 += 1
    count5 += 1
print(M)

结果应该是这样的：

if M[count4].index(M[count4][count5]) == c_idx :
IndexError: list index out of range

---

我看不出我做错了什么。帮帮我，伙计们

只需删除

count4+=1

和

count5+=1

[[3.5, 1.0, 0, 4.0], [0, 0, 0, 0], [3.0, 1.0, 0, -2.0]]

M = [[3.5, 1.0, 9.2, 4.0], [0, 0, 0, 0], [3.0, 1.0, 8.0, -2.0]]

c_idx = 2
for sublist in M:
    sublist[c_idx] = 0 # change the third element to 0 in each sublist
print(M)

范围中的
for/loop
已经为您执行了
+=1
。
不过，其他答案中提到了更为简洁的方法。
您能解释/展示您的预期结果吗？[[3.5,1.0,0,4.0]，[0,0,0]，[3.0,1.0,0，-2.0]]
M = [[3.5, 1.0, 9.2, 4.0], [0, 0, 0, 0], [3.0, 1.0, 8.0, -2.0]]

c_idx = 2
for sublist in M:
    sublist[c_idx] = 0 # change the third element to 0 in each sublist
print(M)

M = [[3.5, 1.0, 9.2, 4.0], [0, 0, 0, 0], [3.0, 1.0, 8.0, -2.0]]
c_idx = 2
for count4 in range(len(M)):
    for count5 in range(len(M[count4])):
        if M[count4].index(M[count4][count5]) == c_idx :
            M[count4] = M[count4][ :c_idx] + [0] + M[count4][c_idx+1 : ]

print(M)
[[3.5, 1.0, 0, 4.0], [0, 0, 0, 0], [3.0, 1.0, 0, -2.0]]