我有一个熊猫数据帧,其中包含学生和他们获得的分数百分比。有些学生的分数显示为大于 100%。显然这些值是不正确的,我想用 NaN 替换所有大于 100% 的百分比值。
我已经尝试了一些代码,但不太能够得到我想要的东西。
import numpy as np
import pandas as pd
new_DF = pd.DataFrame({'Student' : ['S1', 'S2', 'S3', 'S4', 'S5'],
'Percentages' : [85, 70, 101, 55, 120]})
# Percentages Student
#0 85 S1
#1 70 S2
#2 101 S3
#3 55 S4
#4 120 S5
new_DF[(new_DF.iloc[:, 0] > 100)] = np.NaN
# Percentages Student
#0 85.0 S1
#1 70.0 S2
#2 NaN NaN
#3 55.0 S4
#4 NaN NaN
如您所见,代码类型有效,但它实际上替换了该特定行中的所有值,其中百分比大于 NaN 的 100。我只想将百分比列中的值替换为大于 100 的 NaN。有什么办法可以做到这一点吗?
尝试使用np.where
:
new_DF.Percentages=np.where(new_DF.Percentages.gt(100),np.nan,new_DF.Percentages)
或
new_DF.loc[new_DF.Percentages.gt(100),'Percentages']=np.nan
print(new_DF)
Student Percentages
0 S1 85.0
1 S2 70.0
2 S3 NaN
3 S4 55.0
4 S5 NaN
另外,
df.Percentages = df.Percentages.apply(lambda x: np.nan if x>100 else x)
或
df.Percentages = df.Percentages.where(df.Percentages<100, np.nan)
您可以使用 .loc:
new_DF.loc[new_DF['Percentages']>100, 'Percentages'] = np.NaN
输出:
Student Percentages
0 S1 85.0
1 S2 70.0
2 S3 NaN
3 S4 55.0
4 S5 NaN
import numpy as np
import pandas as pd
new_DF = pd.DataFrame({'Student' : ['S1', 'S2', 'S3', 'S4', 'S5'],
'Percentages' : [85, 70, 101, 55, 120]})
#print(new_DF['Student'])
index=-1
for i in new_DF['Percentages']:
index+=1
if i > 100:
new_DF['Percentages'][index] = "nan"
print(new_DF)