根据某些列值选择行返回空 dataframe

Question

我想根据某个列变量的不同值从 dataframe 中提取 select 行并制作直方图。

import numpy as np
import pandas as pd
import csv
import matplotlib.pyplot as plt

df_train=pd.read_csv(r'C:\users\visha\downloads\1994_census\adult.data')
df_train.columns = ["age", "workclass", "fnlwgt", "education",
"educationnum", "maritalstatus", "occupation",
"relationship", "race", "sex", "capitalgain",
"capitalloss", "hoursperweek", "nativecountry",
"incomelevel"]

df_train.dropna(how='any')
df_train.loc[(df_train!=0).any(axis=1)]
#df_train.incomelevel = pd.to_numeric(df_train.incomelevel, errors = 
'coerce').fillna(0).astype('Int64')
df_train.drop(columns='fnlwgt', inplace = True)

#df_test=pd.read_csv(r'C:\users\visha\downloads\1994_census\adult.test')

#df_train.boxplot(column = 'age', by = 'incomelevel', grid = False)

df_train.loc[df_train['incomelevel'] == '<=50K']
#df_train.loc[df_train['incomelevel'] == '>50K']

Output：空 DataFrame 列：[年龄，工种，fnlwgt，教育，教育，婚姻状况，职业，关系，种族，性别，资本收益，资本损失，每周工作时间，本国，收入水平]指数：[]

从以上几行您可以得出我正在尝试 select 收入水平为“<=50K”的行。 “incomelevel”列是 object 数据类型。 但是当我尝试打印它时，它只返回所有列名并提到 dataframe 为“空”。 或者当我在没有打印 function 的情况下在 jupyter 笔记本中运行它时，它只显示 dataframe 以及所有列名，除了这些列下没有任何内容。

Answer 1

您应该使用skipinitialspace=True调用 csv 因为每个值的前面都有空格，然后它可以工作：

df = pd.read_csv('adult.data', header=None, skipinitialspace=True)
df.columns = ["age", "workclass", "fnlwgt", "education",
"educationnum", "maritalstatus", "occupation",
"relationship", "race", "sex", "capitalgain",
"capitalloss", "hoursperweek", "nativecountry",
"incomelevel"]
df = df[df['incomelevel']=='<=50K']
print(df.head())

  age         workclass  fnlwgt  education  educationnum       maritalstatus  ...     sex capitalgain capitalloss hoursperweek  nativecountry  incomelevel
0   39         State-gov   77516  Bachelors            13       Never-married  ...    Male        2174           0           40  United-States        <=50K
1   50  Self-emp-not-inc   83311  Bachelors            13  Married-civ-spouse  ...    Male           0           0           13  United-States        <=50K
2   38           Private  215646    HS-grad             9            Divorced  ...    Male           0           0           40  United-States        <=50K
3   53           Private  234721       11th             7  Married-civ-spouse  ...    Male           0           0           40  United-States        <=50K
4   28           Private  338409  Bachelors            13  Married-civ-spouse  ...  Female           0           0           40           Cuba        <=50K