我正在嘗試在數(shù)據(jù)框中創(chuàng)建一個新列，該列根據(jù)另一列中的值分配值。我使用的代碼分配了值，但不是我想要的。我不確定我錯過了什么。代碼示例如下：#define track stylesshort = [4,6,8,9,11,20,24,28,30,33,35]inter = [2,3,7,12,13,17,19,25,27,32,34,36]long = [5,14,15,21,23,26]plate = [1,10,18,31]road = [16,22,29]#input driver and stat info driver1 = input('Choose driver: ')#read driver data to dataframedf = pd.read_csv(driver1 + '_2018.csv')#add track typedf['Type'] = ''for i in range(len(df)): if df['Race'][i] in short: df['Type'][i] = 'short' elif df['Race'][i] in inter: df['Type'] = 'intermediate' elif df['Race'][i] in long: df['Type'] = 'long' elif df['Race'][i] in plate: df['Type'] = 'plate' else: df['Type'] = 'road'print(df.head())我得到以下輸出：C:\EclipseWorkspace\csse120\Personal\NASCAR_Projects\Other\driver_review.py:45: SettingWithCopyWarning: A value is trying to be set on a copy of a slice from a DataFrameSee the caveats in the documentation: http://pandas.pydata.org/pandas-docs/stable/indexing.html#indexing-view-versus-copy df['Type'][i] = 'short' Race Start Mid Race ... Total Laps DRIVER RATING Type0 1 5 23 ... 207 105.2 intermediate1 2 16 7 ... 325 94.2 intermediate2 3 10 2 ... 267 106.1 intermediate3 4 5 11 ... 311 80.0 intermediate4 5 6 3 ... 200 113.0 intermediate[5 rows x 20 columns]請注意，“類型”列返回所有“中間”，而它應(yīng)該包括 ['plate', 'intermediate', 'intermediate', 'short', 'long']。
1 回答
qq_笑_17
TA貢獻(xiàn)1818條經(jīng)驗 獲得超7個贊
使用map和dictionary- 首先通過鍵中的新名稱和值中的列表創(chuàng)建字典，然后在字典理解中相互交換到平面字典：
d = {'short':short,
'intermediate':inter,
'long':long,
'plate':plate,
'road':road}
d1 = {k: oldk for oldk, oldv in d.items() for k in oldv}
df['Type'] = df['Race'].map(d1)
print (df)
Race Start Mid Race Total Laps DRIVER RATING Type
0 1 5 23 207 105.2 plate
1 2 16 7 325 94.2 intermediate
2 3 10 2 267 106.1 intermediate
3 4 5 11 311 80.0 short
4 5 6 3 200 113.0 long
如果想要將前 4 個類別中不匹配的所有值設(shè)置為從第一個字典中road刪除road并添加fillna所有不匹配的值：
d = {'short':short,
'intermediate':inter,
'long':long,
'plate':plate}
d1 = {k: oldk for oldk, oldv in d.items() for k in oldv}
df['Type'] = df['Race'].map(d1).fillna('road')
詳情：
print (d1)
{
4: 'short', 6: 'short',
8: 'short', 9: 'short',
11: 'short', 20: 'short',
24: 'short', 28: 'short',
30: 'short', 33: 'short',
35: 'short', 2: 'intermediate',
3: 'intermediate', 7: 'intermediate',
12: 'intermediate', 13: 'intermediate',
17: 'intermediate', 19: 'intermediate',
25: 'intermediate', 27: 'intermediate',
32: 'intermediate', 34: 'intermediate',
36: 'intermediate', 5: 'long',
14: 'long', 15: 'long',
21: 'long', 23: 'long',
26: 'long', 1: 'plate',
10: 'plate', 18: 'plate',
31: 'plate', 16: 'road',
22: 'road', 29: 'road'
}
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