有一个 pandas dataframe 如下:
import pandas as pd
raw_data = {'name': ['Willard Morris', 'Al Jennings', 'Omar Mullins', 'Spencer McDaniel'],
'age': [20, 19, 22, 21],
'favorite_color': ['blue', 'blue', 'yellow', "green"],
'grade': [88, 92, 95, 70]}
df = pd.DataFrame(raw_data)
我想将 age 和 grade 数字单元格值除以等于 favorite_color 列中的 blue 到 125.0 值和黄色 值分为 130.0，绿色 分为 135.0。结果必须插入新列 age_new、grade_new。 通过下面的代码我收到错误。
df['age_new'] =(df.loc[df['favorite_color']=='blue']/125.0)
df['age_new'] =(df.loc[df['favorite_color']=='yellow']/130.0)
df['age_new'] =(df.loc[df['favorite_color']=='green']/135.0)
df['grade_new'] =(df.loc[df['favorite_color']=='blue']/125.0)
df['grade_new'] =(df.loc[df['favorite_color']=='yellow']/130.0)
df['grade_new'] =(df.loc[df['favorite_color']=='green']/135.0)
错误:
TypeError: unsupported operand type(s) for /: 'str' and 'int'
请您参考如下方法:
map
mods = {'blue': 125, 'yellow': 130, 'green': 135}
df.assign(
mods=df.favorite_color.map(mods),
age_new=lambda d: d.age / d.mods,
grade_new=lambda d: d.grade / d.mods
)
name age favorite_color grade mods age_new grade_new
0 Willard Morris 20 blue 88 125 0.160000 0.704000
1 Al Jennings 19 blue 92 125 0.152000 0.736000
2 Omar Mullins 22 yellow 95 130 0.169231 0.730769
3 Spencer McDaniel 21 green 70 135 0.155556 0.518519
类似
mods = {'blue': 125, 'yellow': 130, 'green': 135}
df.join(df[['age', 'grade']].div(df.favorite_color.map(mods), axis=0).add_suffix('_new'))
name age favorite_color grade age_new grade_new
0 Willard Morris 20 blue 88 0.160000 0.704000
1 Al Jennings 19 blue 92 0.152000 0.736000
2 Omar Mullins 22 yellow 95 0.169231 0.730769
3 Spencer McDaniel 21 green 70 0.155556 0.518519
