# 如何更改 Panas DataFrame 列的順序

## 以新順序在對 `pandas.DataFrame` 列排序

``````# python 3.x
import pandas as pd

df = pd.DataFrame(
{
"a": ["1", "2", "3", "4"],
"b": [16, 7, 6, 16],
"c": [61, 57, 16, 36],
"d": ["12", "22", "13", "44"],
"e": ["Green", "Red", "Blue", "Yellow"],
"f": [1, 11, 23, 66],
}
)
print(df)
df = df[["e", "c", "b", "f", "d", "a"]]
print("Rearranging ..................")
print("..............................")
print(df)
``````

``````   a   b   c   d       e   f
0  1  16  61  12   Green   1
1  2   7  57  22     Red  11
2  3   6  16  13    Blue  23
3  4  16  36  44  Yellow  66
Rearranging ..................
..............................
e   c   b   f   d  a
0   Green  61  16   1  12  1
1     Red  57   7  11  22  2
2    Blue  16   6  23  13  3
3  Yellow  36  16  66  44  4
``````

## 在 Pandas 中用 `insert` 新增新列和位置

``````# python 3.x
import pandas as pd

df = pd.DataFrame(
{
"a": ["1", "2", "3", "4"],
"b": [16, 7, 6, 16],
"c": [61, 57, 16, 36],
"d": ["12", "22", "13", "44"],
"e": ["Green", "Red", "Blue", "Yellow"],
"f": [1, 11, 23, 66],
}
)
print(df)
print("Inserting ..................")
print("..............................")
df.insert(0, "newColMean", df.mean(1))
print(df)
``````

``````   newColMean  a   b   c   d       e   f
0   26.000000  1  16  61  12   Green   1
1   25.000000  2   7  57  22     Red  11
2   15.000000  3   6  16  13    Blue  23
3   39.333333  4  16  36  44  Yellow  66
``````

## Pandas 中給定順序的 `reindex` 列

`reindex` 可以說是重新排列列的最有效方法：

``````# python 3.x
import pandas as pd

df = pd.DataFrame(
{
"a": ["1", "2", "3", "4"],
"b": [16, 7, 6, 16],
"c": [61, 57, 16, 36],
"d": ["12", "22", "13", "44"],
"e": ["Green", "Red", "Blue", "Yellow"],
"f": [1, 11, 23, 66],
}
)
print(df)
print("Rearranging ..................")
print("..............................")
df = df.reindex(columns=["a", "f", "d", "b", "c", "e"])
print(df)
``````

``````   a   b   c   d       e   f
0  1  16  61  12   Green   1
1  2   7  57  22     Red  11
2  3   6  16  13    Blue  23
3  4  16  36  44  Yellow  66
Rearranging ..................
..............................
a   f   d   b   c       e
0  1   1  12  16  61   Green
1  2  11  22   7  57     Red
2  3  23  13   6  16    Blue
3  4  66  44  16  36  Yellow
``````