The pandas.DataFrame.query()
method is of great usage for (pre/post)-filtering data when loading or plotting. It comes particularly handy for method chaining.
Instead of query you can use pipe
:
s.pipe(lambda x: x[x>0]).pipe(lambda x: x[x<10])
IIUC you can add query("Points > 100")
:
df = pd.DataFrame({'Points':[50,20,38,90,0, np.Inf],
'Player':['a','a','a','s','s','s']})
print (df)
Player Points
0 a 50.000000
1 a 20.000000
2 a 38.000000
3 s 90.000000
4 s 0.000000
5 s inf
points_series = df.query("Points < inf").groupby("Player").agg({"Points": "sum"})['Points']
print (points_series)
a = points_series[points_series > 100]
print (a)
Player
a 108.0
Name: Points, dtype: float64
points_series = df.query("Points < inf")
.groupby("Player")
.agg({"Points": "sum"})
.query("Points > 100")
print (points_series)
Points
Player
a 108.0
Another solution is Selection By Callable:
points_series = df.query("Points < inf")
.groupby("Player")
.agg({"Points": "sum"})['Points']
.loc[lambda x: x > 100]
print (points_series)
Player
a 108.0
Name: Points, dtype: float64
Edited answer by edited question:
np.random.seed(1234)
df = pd.DataFrame({
'Points': [np.random.choice([1,3]) for x in range(100)],
'Player': [np.random.choice(["A","B","C"]) for x in range(100)]})
print (df.query("Points == 3").Player.value_counts().loc[lambda x: x > 15])
C 19
B 16
Name: Player, dtype: int64
print (df.query("Points == 3").groupby("Player").size().loc[lambda x: x > 15])
Player
B 16
C 19
dtype: int64
Why not convert from Series to DataFrame, do the querying, and then convert back.
df["Points"] = df["Points"].to_frame().query('Points > 100')["Points"]
Here, .to_frame()
converts to DataFrame, while the trailing ["Points"]
converts to Series.
The method .query()
can then be used consistently whether or not the Pandas object has 1 or more columns.