Question

我有一个数据帧df如下：

Name   Race(m)    Date  
Peter   2000    23/09/16  
Mary    100     23/09/16
Mary    400     23/09/16
Mary    200     23/09/16
Mary    400     24/09/17
John    800     23/09/16

我想添加一个专栏[X]来表示该人在同一天仍有多少次比赛：

Name   Race(m)    Date       X
Peter   2000    23/09/16     1
Peter   100     23/09/16     0
Mary    400     23/09/16     1
Mary    200     23/09/16     0
Mary    400     24/09/17     0
John    800     23/09/16     0

实现目标：

content = df.values.tolist()
name = []
date = []
for each in content:
    if (each[0] not in name and (each[2] not in date)) or ((each[0] in name) and (each[2] not in date)) or ((each[0] not in name) and (each[2] in date)):
        remaining_race = 0
        for every in content:
            if every[0] == each[0] and every[2] == each[2]:
                remaining_race += 1
        remaining_race -= 1    
        name.append(each[0])
        date.append(each[2])
        each.append(remaining_race)

    else:
        remaining_race -= 1
        each.append(remaining_race)

然而，输出是：

    Name   Race(m)    Date       X
    Peter   2000    23/09/16     1
    Peter   100     23/09/16     0
    Mary    400     23/09/16     -1
    Mary    200     23/09/16     -2
    Mary    400     24/09/17     0
    John    800     23/09/16     -3

我该如何解决？

Answer 1

import pandas as pd
df = pd.DataFrame(data=[["peter"],["peter"]], columns=["name"]) 
# count number of times each name occurs, put it in a dictionary
names = dict(df["name"].value_counts())

def num_races_left(name):
  names[name]-=1
  return names[name]

# for every name, look it up in the dict and reduce number by 1
df["X"] = df["name"].apply(num_races_left)

返回以下内容

    name  X
0  peter  1
1  peter  0

＆＃39;和＆＃39; ＆＃39;或＆＃39; if语句中的运算符

1 个答案: