Python: Random selection per group

Question

Say that I have a dataframe that looks like:

Name Group_Id
AAA  1
ABC  1
CCC  2
XYZ  2
DEF  3 
YYH  3

How could I randomly select one (or m

Answer 1

A very pandas-ish way:

takesamp = lambda d: d.sample(n)
df = df.groupby('Group_Id').apply(takesamp)

Answer 2

Using groupby and random.choice in an elegant one liner:

df.groupby('Group_Id').apply(lambda x :x.iloc[random.choice(range(0,len(x)))])

Answer 3

The solutions offered fail if a group has fewer samples than the desired sample size n. This addresses this problem:

n = 10
df.groupby('Group_Id').apply(lambda x: x.sample(min(n,len(x)))).reset_index(drop=True)