python - 转置具有多列的 Pandas 数据框

Question

我有一个目前看起来像这样的数据框:

import numpy as np
raw_data = {'Series_Date':['2017-03-10','2017-03-13','2017-03-14','2017-03-15'],'SP':[35.6,56.7,41,41],'1M':[-7.8,56,56,-3.4],'3M':[24,-31,53,5]}
import pandas as pd
df = pd.DataFrame(raw_data,columns=['Series_Date','SP','1M','3M'])
print df

我想以一种方式转置所有值字段都转置到值列并将日期附加为行项目。值字段的列名称成为描述列的一行。即生成的 Dataframe 应如下所示:

import numpy as np
raw_data = {'Series_Date':['2017-03-10','2017-03-10','2017-03-10','2017-03-13','2017-03-13','2017-03-13','2017-03-14','2017-03-14','2017-03-14','2017-03-15','2017-03-15','2017-03-15'],'Value':[35.6,-7.8,24,56.7,56,-31,41,56,53,41,-3.4,5],'Desc':['SP','1M','3M','SP','1M','3M','SP','1M','3M','SP','1M','3M']}
import pandas as pd
df = pd.DataFrame(raw_data,columns=['Series_Date','Value','Desc'])
print df

有人可以帮助我如何以这种方式翻转和转置我的 DataFrame 吗？

Answer 1

使用pd.melt将 DF 从宽格式转换为长格式:

idx = "Series_Date"              # identifier variable
pd.melt(df, id_vars=idx, var_name="Desc").sort_values(idx).reset_index(drop=True)