如何添加行元素并将其添加到列表中

Question

我有以下代码：

nilai = [[70,50,80],
     [100,80,90],
     [100,40,70],
     [80,50,60]]
rata_rata = []

for i in range(0,len(nilai)):
    for j in range(0,len(nilai)):
        row = 0.2 * nilai[i][j] + 0.3 * nilai[i][j] + 0.5 * nilai[i][j]
        rata_rata.append(row)

我想知道如何访问列nilai[i]中的元素？

Answer 1

您使生活复杂化。请改用pandas。这很简单：

import pandas as pd     # pip install pandas

nilai = [[70,50,80],
     [100,80,90],
     [100,40,70],
     [80,50,60]]

df = pd.DataFrame(nilai)    # creating a table flom nilai

df[3] = 0.2 * df[0] + 0.3 * df[1] + 0.5 * df[2]   # operation with whole columns

测试：

print(df)

     0   1   2     3
0   70  50  80  69.0
1  100  80  90  89.0
2  100  40  70  67.0
3   80  50  60  61.0

Answer 2

您的第二个for loop不正确。

已修复。

nilai = [[70,50,80],
     [100,80,90],
     [100,40,70],
     [80,50,60]]
rata_rata = []

for i in range(0,len(nilai)):
    # use nilai[0]
    for j in range(0,len(nilai[0])):
        row = 0.2 * nilai[i][j] + 0.3 * nilai[i][j] + 0.5 * nilai[i][j]
        rata_rata.append(row)

而且，由于这是默认行为，因此您无需显式告诉range从0开始。

输出：

[70.0, 50.0, 80.0, 100.0, 80.0, 90.0, 100.0, 40.0, 70.0, 80.0, 50.0, 60.0]

Answer 3

我想您想做的事情可以通过list comprehension轻松完成

nilai = [[70,50,80],
     [100,80,90],
     [100,40,70],
     [80,50,60]]
rata_rata = [0.2 * i + 0.3 * i + 0.5 * i for lst in nilai for i in lst]
print(rata_rata)

运行时输出：

[70.0, 50.0, 80.0, 100.0, 80.0, 90.0, 100.0, 40.0, 70.0, 80.0, 50.0, 60.0]