Pandas compte les lignes avec valeur
len(df[df['score'] == 1.0])
Wrong Wryneck
len(df[df['score'] == 1.0])
df['freq'] = df.groupby('myvar')['myvar'].transform('count')
df = pd.DataFrame({'a':list('abssbab')})
df.groupby('a').count()
>>> df.set_index(["Person", "Single"]).count(level="Person")
Age
Person
John 2
Lewis 1
Myla 1