Python 如何在熊猫中组合宽数据帧和长数据帧?
我有以下数据帧Python 如何在熊猫中组合宽数据帧和长数据帧?,python,python-3.x,pandas,dataframe,melt,Python,Python 3.x,Pandas,Dataframe,Melt,我有以下数据帧 data = {'Name':['Tom', 'nick', 'krish', 'jack'], 'Age':[20, 21, 19, 18], 'Height':[23, 43, 123, 12], 'Hair_Width':[21, 11, 23, 14]} df = pd.DataFrame(data) df Name Age Height Hair_Width 0 Tom 20 23 21 1 nick 21 43
data = {'Name':['Tom', 'nick', 'krish', 'jack'], 'Age':[20, 21, 19, 18], 'Height':[23, 43, 123, 12], 'Hair_Width':[21, 11, 23, 14]}
df = pd.DataFrame(data)
df
Name Age Height Hair_Width
0 Tom 20 23 21
1 nick 21 43 11
2 krish 19 123 23
3 jack 18 12 14
我在此数据帧上执行了如下熔化操作:
pd.melt(df, id_vars=['Name'], value_vars=['Age', 'Height'])
df
Name variable value
0 Tom Age 20
1 nick Age 21
2 krish Age 19
3 jack Age 18
4 Tom Height 23
5 nick Height 43
6 krish Height 123
7 jack Height 12
但是,我希望将新的数据帧与原始(宽)数据帧中的一个变量结合起来,以获得以下所需的输出:
Name variable value Hair_Width
0 Tom Age 20 21
1 nick Age 21 11
2 krish Age 19 23
3 jack Age 18 14
4 Tom Height 23 21
5 nick Height 43 11
6 krish Height 123 23
7 jack Height 12 14
我很想听到关于如何实现这一目标的任何建议
编辑:许多人正确地指出原始数据集的格式很整齐。这是正确的-这只是一个简单的例子。实际的数据帧开始时并不整齐。因此您已经有了数据输入和融化过程(老实说,不确定您为什么决定融化它,因为原始数据的格式看起来很整齐): 我已经提供了我在上面使用的名称。进行合并,然后poof:
new_df.merge(df[['Name', 'Hair_Width']], on='Name', how='left')
Out[25]:
Name variable value Hair_Width
0 Tom Age 20 21
1 nick Age 21 11
2 krish Age 19 23
3 jack Age 18 14
4 Tom Height 23 21
5 nick Height 43 11
6 krish Height 123 23
7 jack Height 12 14
使用映射
:
df_out = pd.melt(df, id_vars=['Name'], value_vars=['Age', 'Height'])
df_out['Hair_Width'] = df_out['Name'].map(df.set_index('Name')['Hair_Width'])
df_out
输出:
Name variable value Hair_Width
0 Tom Age 20 21
1 nick Age 21 11
2 krish Age 19 23
3 jack Age 18 14
4 Tom Height 23 21
5 nick Height 43 11
6 krish Height 123 23
7 jack Height 12 14
Name variable value Hair_Width
0 Tom Age 20 21
1 nick Age 21 11
2 krish Age 19 23
3 jack Age 18 14
4 Tom Height 23 21
5 nick Height 43 11
6 krish Height 123 23
7 jack Height 12 14
Name variable value Hair_Width
0 Tom Age 20 21
1 nick Age 21 11
2 krish Age 19 23
3 jack Age 18 14
4 Tom Height 23 21
5 nick Height 43 11
6 krish Height 123 23
7 jack Height 12 14
只需在
熔化时添加Hair\u Width
作为另一个id\u var
,之后无需执行任何操作
除了其他问题之外,我不知道为什么您首先要将形状改为long,但您可以通过方法链接轻松实现这一点
newdf = (df
.melt(id_vars='Name', value_vars=['Age', 'Height'])
.merge(df[['Name', 'Hair_Width']], how='left', on='Name'))
输出:
Name variable value Hair_Width
0 Tom Age 20 21
1 nick Age 21 11
2 krish Age 19 23
3 jack Age 18 14
4 Tom Height 23 21
5 nick Height 43 11
6 krish Height 123 23
7 jack Height 12 14
Name variable value Hair_Width
0 Tom Age 20 21
1 nick Age 21 11
2 krish Age 19 23
3 jack Age 18 14
4 Tom Height 23 21
5 nick Height 43 11
6 krish Height 123 23
7 jack Height 12 14
Name variable value Hair_Width
0 Tom Age 20 21
1 nick Age 21 11
2 krish Age 19 23
3 jack Age 18 14
4 Tom Height 23 21
5 nick Height 43 11
6 krish Height 123 23
7 jack Height 12 14
或者分两个阶段进行,如
melted = df.melt(id_vars='Name', value_vars=['Age', 'Height'])
newdf = melted.merge(df[['Name', 'Hair_Width']], how='left', on='Name')
输出:
Name variable value Hair_Width
0 Tom Age 20 21
1 nick Age 21 11
2 krish Age 19 23
3 jack Age 18 14
4 Tom Height 23 21
5 nick Height 43 11
6 krish Height 123 23
7 jack Height 12 14
Name variable value Hair_Width
0 Tom Age 20 21
1 nick Age 21 11
2 krish Age 19 23
3 jack Age 18 14
4 Tom Height 23 21
5 nick Height 43 11
6 krish Height 123 23
7 jack Height 12 14
Name variable value Hair_Width
0 Tom Age 20 21
1 nick Age 21 11
2 krish Age 19 23
3 jack Age 18 14
4 Tom Height 23 21
5 nick Height 43 11
6 krish Height 123 23
7 jack Height 12 14
原始数据帧不宽。看起来它的格式很整齐,不应该改变。