Python 用行号填充一个新的 Pandas 列
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Fill a new pandas column with row numbers
提问by michael0196
I have the following DataFrame datawith random index values:
我有以下data带有随机索引值的DataFrame ：
A B
100 0 7
203 5 4
5992 0 10
2003 9 8
20 10 5
12 6 2
I would like to add a new column 'C' with row numbers. For example:
我想添加一个带有行号的新列“C”。例如：
A B C
100 0 7 0
203 5 4 1
5992 0 10 2
2003 9 8 3
20 10 5 4
12 6 2 5
Thank you for your help!
感谢您的帮助！
回答by jezrael
Use numpy.arangeby length of DataFrame:
numpy.arange按长度使用DataFrame：
df['C'] = np.arange(len(df))
print (df)
A B C
100 0 7 0
203 5 4 1
5992 0 10 2
2003 9 8 3
20 10 5 4
12 6 2 5
回答by YOBEN_S
By using reset_index
通过使用 reset_index
df['C'] = df.reset_index().index
df
A B C
100 0 7 0
203 5 4 1
5992 0 10 2
2003 9 8 3
20 10 5 4
12 6 2 5
To generalise:
概括地说：
df['C'] = df.index if df.index.is_monotonic_increasing else range(len(df))
df
A B C
100 0 7 0
203 5 4 1
5992 0 10 2
2003 9 8 3
20 10 5 4
12 6 2 5
回答by kamran kausar
We can add new column with row numbers as first column as following:
我们可以添加行号作为第一列的新列，如下所示：
import pandas as pd
import numpy as np
df = pd.DataFrame({'B': [1, 2, 3], 'C': [4, 5, 6]})
B C
0 1 4
1 2 5
2 3 6
df.insert(loc=0, column='A', value=np.arange(len(df)))
A B C
0 0 1 4
1 1 2 5
2 2 3 6
