英文:
Get ranking within Pandas.DataFrame with ties as possibility
问题
我有以下示例
import pandas as pd
names = ['a', 'b', 'c', 'd', 'e']
points = [10, 15, 15, 12, 20]
scores = pd.DataFrame({'name': names,
'points': points})
我想创建一个名为position的新列，该列指定了玩家的相对位置。拥有最多积分的玩家是#1。
我使用以下代码对df进行排序：
scores = scores.sort_values(by='points', ascending=False)
如果存在平局（相同的积分数），我希望position是T和相应的位置。在我的示例中，b和c的位置是T2。
期望输出：
name points position
e 20 1
b 15 T2
c 15 T2
d 12 3
a 10 4
谢谢。
英文:
I have the following example
import pandas as pd
names = ['a', 'b', 'c', 'd', 'e']
points = [10, 15, 15, 12, 20]
scores = pd.DataFrame({'name': names,
'points': points})
I want to create a new column called position that specifies the relative position of a player. The player with the most points is #1.
I sort the df using
scores = scores.sort_values(by='points', ascending=False)
If there is a tie (same number of points) I want position to be the T and the corresponding position.
In my example the position of b and c is T2.
Desired output:
name points position
e 20 1
b 15 T2
c 15 T2
d 12 3
a 10 4
Thank you
答案1
得分: 1
# 是否有并列？
m = scores["points"].duplicated(keep=False)
# 计算排名
s = scores["points"].rank(method="dense", ascending=False)
scores["position"] = (
s.where(~m, s.astype(str).radd("T"))
.astype(str)
.replace(".0$", "", regex=True)
)
out = scores.sort_values(by="points", ascending=False)
# 输出：
print(out)
姓名 分数 排名
4 e 20 1
1 b 15 T2
2 c 15 T2
3 d 12 3
0 a 10 4
英文:
I would use pandas.Series.rank :
# is there a tie ?
m = scores["points"].duplicated(keep=False)
# calculate rankings
s = scores["points"].rank(method="dense", ascending=False)
scores["position"] = (
s.where(~m, s.astype(str).radd("T"))
.astype(str)
.replace(".0$", "", regex=True)
)
out = scores.sort_values(by="points", ascending=False)
# Output :
print(out)
name points position
4 e 20 1
1 b 15 T2
2 c 15 T2
3 d 12 3
0 a 10 4
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