fit.resid 给出错误“尝试使用 .loc[row_indexer,col_indexer] = value 代替”？答案

【问题标题】：fit.resid gives error 'Try using .loc[row_indexer,col_indexer] = value instead'?fit.resid 给出错误“尝试使用 .loc[row_indexer,col_indexer] = value 代替”？
【发布时间】：2017-11-28 20:56:11
【问题描述】：

下面是数据框：

   CNSSSBDVSN     CNSSSBDVS1                CNMCRGNNM  \
0     5941833      Kluskus 1                  Cariboo   
1     5949832        Iskut 6  North Coast / Cote-nord   
2     5941016      Cariboo H                  Cariboo   
3     5955040  Peace River B     Northeast / Nord-est   
4     5941801  Alkali Lake 1                  Cariboo   

                         CNSSSBDVS3  instagram_posts  airports  \
0                    Indian Reserve                0         0   
1                    Indian Reserve                0         0   
2  Regional District Electoral Area                0         0   
3  Regional District Electoral Area                1        17   
4                    Indian Reserve                0         0   

   railway_stations  accommodations  visitor_centers  festivals  \
0                 0               0                0          0   
1                 0               0                0          0   
2                 0               5                0          0   
3                11               0                0          0   
4                 0               0                0          0   

   ports_and_ferry_terminals  attractions  
0                          0            0  
1                          0            0  
2                          0            0  
3                          0            0  
4                          0            0

下面是代码。在您阅读之前，我想提两点： 1. 我认为残差或索引出了点问题 2. CNSSSBDVSN 可以根据需要作为索引使用

# -*- coding: utf-8 -*-
import pandas as pd
import statsmodels.formula.api as sm
import matplotlib.pyplot as plt
import scipy.stats as stats

from tabulate import tabulate


if __name__ == "__main__":

    # Read data
    census_subdivision_without_lower_mainland_and_van_island = pd.read_csv('../data/augmented/census_subdivision_without_lower_mainland_and_van_island.csv')

    # Select data
    cities = census_subdivision_without_lower_mainland_and_van_island[census_subdivision_without_lower_mainland_and_van_island['CNSSSBDVS3'] == 'City']
    non_cities = census_subdivision_without_lower_mainland_and_van_island[census_subdivision_without_lower_mainland_and_van_island['CNSSSBDVS3'] != 'City']

    # Fit
    fit_cities = sm.ols(formula="instagram_posts ~ airports + railway_stations + ports_and_ferry_terminals + accommodations + visitor_centers + festivals  + attractions", data=cities).fit()
    fit_non_cities = sm.ols(formula="instagram_posts ~ airports + railway_stations + ports_and_ferry_terminals + accommodations + visitor_centers + festivals  + attractions", data=non_cities).fit()

    print(fit_cities.summary())
    print(fit_non_cities.summary())

    # Residual
    cities['residual'] = fit_cities.resid
    non_cities['residual'] = fit_non_cities.resid

给出错误：

/Users/Chu/Documents/dssg/done/linear_model_cities.py:27: SettingWithCopyWarning: 
A value is trying to be set on a copy of a slice from a DataFrame.
Try using .loc[row_indexer,col_indexer] = value instead

See the caveats in the documentation: http://pandas.pydata.org/pandas-docs/stable/indexing.html#indexing-view-versus-copy
  cities['residual'] = fit_cities.resid
/Users/Chu/Documents/dssg/done/linear_model_cities.py:28: SettingWithCopyWarning: 
A value is trying to be set on a copy of a slice from a DataFrame.
Try using .loc[row_indexer,col_indexer] = value instead

See the caveats in the documentation: http://pandas.pydata.org/pandas-docs/stable/indexing.html#indexing-view-versus-copy
  non_cities['residual'] = fit_non_cities.resid

【问题讨论】：

标签： python pandas dataframe statistics statsmodels

【解决方案1】：

您的问题是城市是人口普查的一部分_subdivision_without_lower_mainland_and_van_island 如果您想从这里开始使用城市作为自己的数据框，您可以创建一个副本：

cities = census_subdivision_without_lower_mainland_and_van_island[census_subdivision_without_lower_mainland_and_van_island['CNSSSBDVS3'] == 'City'].copy()

或者，如果您希望修改原始数据框，您可以使用 loc 插入结果，如提到的错误：

census_subdivision_without_lower_mainland_and_van_island.loc[census_subdivision_without_lower_mainland_and_van_island['CNSSSBDVS3'] == 'City','residuals'] = fit_cities.resid

对于非城市也是如此。作为一个参考，我会使用较短的数据框名称，以使您的代码保持可读性并在推荐的 python 行限制内

【讨论】：

是的，本质上，它定义了索引的一个切片，但该切片仍指向原始数据帧，因此警告试图防止您意外修改原始数据。这就是复制或明确修改原始作品的方式。