python - Pandas: How to combine several rows with the same column value and create a new Dataframe which covers all possibilities?

Question

There exists a DataFrame like this:

id	name	age
0x0	Hans	32
0x0	Peter	21
0x1	Jan	42
0x1	Simon	25
0x1	Klaus	51
0x1	Franz	72

Answer 1

Core python itertools combinations is the solution. merge() to get the age

import itertools
df = pd.read_csv(io.StringIO("""id  name    age
0x0 Hans    32
0x0 Peter   21
0x1 Jan 42
0x1 Simon   25
0x1 Klaus   51
0x1 Franz   72"""), sep="")

df1 = (
df
    .groupby(["id"])["name"]
    .apply(lambda x: pd.DataFrame(itertools.combinations(list(x),2)))
    .reset_index()
    .merge(df, left_on=["id",0], right_on=["id","name"])
    .merge(df, left_on=["id",1], right_on=["id","name"], suffixes=("0","1"))
    .drop(columns=["level_1",0,1])
)

output

  id  name0  age0  name1  age1
 0x0   Hans    32  Peter    21
 0x1    Jan    42  Simon    25
 0x1    Jan    42  Klaus    51
 0x1  Simon    25  Klaus    51
 0x1    Jan    42  Franz    72
 0x1  Simon    25  Franz    72
 0x1  Klaus    51  Franz    72