我如何以某种方式转置熊猫数据框，其中我只需要两列，一列用于标题

Question

I have a Dataframe which looks something along the lines of this:

A B C
1 Data1 Data2 Data3
2 Data3 Data1 Nan
3 Nan Data5 Nan

And basically i want to get a Dataframe which looks like that:

1
A Data1
A Data3
B Data2
B Data1
B Data5
C Data3

I already found out that I am probably going to need the transpose function. But I don't know how to go on from there. I would be glad if you could help me out with that or if you find another way which solves this problem.

Answer 1

You can do a bit of function chaining:

df = df.stack().reset_index(level=0, drop=True).sort_index().dropna()

df.stack() aggregates them in one column but adds a multilevel index so we drop with .reset_index(level=0, drop=True) then we sort the index so it orders the text with sort_index() then finally we dropna() .

Outputs:

A    Data1
A    Data3
B    Data2
B    Data1
B    Data5
C    Data3

If you take off each chained assignment and run them individually you can see what each intermediate step is doing: df.stack() then df.stack().reset_index(level=0, drop=True) , then df.stack().reset_index(level=0, drop=True).sort_index()