You are almost there, actually just use flatten instead of reduce to unnest the array (instead of unnesting the list), and chain operations to have a one liner:
df.loc[df.n == "d", ['a','b']].values.flatten().tolist()
#[4, 6]
You are almost there, actually just use flatten instead of reduce to unnest the array (instead of unnesting the list), and chain operations to have a one liner:
df.loc[df.n == "d", ['a','b']].values.flatten().tolist()
#[4, 6]