如何修改数据框中新创建的列的多个行范围？

Question

我在尝试修改数据框中新创建的列的多个行值范围时遇到了问题，希望得到一些帮助。如果之前有人问过这个问题，我深表歉意，如果你能正确指出我，我将不胜感激 direction.I 我是 python 编码

的新手

因此，我从多家公司的损益电子表格中导入了一堆数据，这些数据合并为一个总和；并在进行上述修改以供进一步分析之前对其进行清理：

import pandas as pd
from tabulate import tabulate

dftabulate = lambda df:tabulate(df,headers='keys',tablefmt='psql')
CleanCols = [5,7,8,9,10,11,12,13,14,15,17]
SummaryRows = [0,39,44,58,62,79,87]

VA = pd.read_excel('Columnar BU P&L.xlsx', sheet_name = 'Variance by Co')
VA = VA[98:197]
VA = VA.iloc[:,CleanCols]
VA.columns =  ['Expense','A', 'B', 'C', 'D', 'E', 'F', 'G', 'H', 'I', 'All Companies']
VA = VA.dropna(axis = 0, how = 'any')
VA = VA.reset_index(drop = True)
VAtcols = VA.columns.drop('Expense')
VA[VAtcols] = VA[VAtcols].astype(int)
VM = VA.iloc[SummaryRows]
VA['Exp Category'] = 'NA'
print(dftabulate(VA.head()))

输出如下所示：

                                    Expense      A  ...  All Companies  Exp Category
0  General and Administrative Expenses (G&A) -4550  ...         133886            NA
1                             Communications   -17  ...          -4793            NA
2                              Fuel - Travel     0  ...          -1274            NA
3                             Mileage & Auto   449  ...           -251            NA
4                                     Travel     0  ...           1187            NA

我想要实现的是根据行索引将新创建的 Exp Category 列更改为多个值。例如，我想将 1:12 行更改为 Travel & Entertainment 等。当我使用以下代码创建此分类时，它不会引发错误，但不会更改 NA 分配给该列的值，我似乎无法弄清楚我在这里做错了什么。

VA[1:12]['Exp Category'] = 'Travel & Entertainment'
VA[13:18]['Exp Category'] = 'Office Supplies & Expenses'
VA[19:24]['Exp Category'] = 'Professional Fees'
VA[25:28]['Exp Category'] = 'Fees & Assessments'
VA[29:30]['Exp Category'] = 'IT Expense'
VA[31:32]['Exp Category'] = 'Bad Debt Expense'
VA[33:38]['Exp Category'] = 'Misc Expense'
VA[40:43]['Exp Category'] = 'Marketing Expenses'
VA[45:57]['Exp Category'] = 'Payroll & Related Expenses'
VA[59:61]['Exp Category'] = 'Utilities Expenses'
VA[63:69]['Exp Category'] = 'Equip Maint & Rental Expenses'
VA[70:78]['Exp Category'] = 'Mill Expenses'
VA[80:82]['Exp Category'] = 'Taxes'
VA[83:86]['Exp Category'] = 'Insurance'
VA[88:89]['Exp Category'] = 'Incentive Compensation'
VA[89:90]['Exp Category'] = 'Strategic Initiative'

输出仍然看起来像这样，带有关于返回视图与副本的警告消息：

                                    Expense      A  ...  All Companies  Exp Category
0  General and Administrative Expenses (G&A) -4550  ...         133886            NA
1                             Communications   -17  ...          -4793            NA
2                              Fuel - Travel     0  ...          -1274            NA
3                             Mileage & Auto   449  ...           -251            NA
4                                     Travel     0  ...           1187            NA

我试图查看 "SettingWithCopyWarning" 消息，但尽管阅读了 material 我还是不明白如何解决它，非常感谢任何反馈！

提前致谢！

Answer 1

使用 pd.loc 可能会达到您的要求：

示例数据帧

import pandas as pd
d = {'a': [1, 2, 3, 4],
     'b': ['NA', 'NA', 'NA', 'NA']}
df = pd.DataFrame(data = d)
df

    a   b
0   1   NA
1   2   NA
2   3   NA
3   4   NA

将pd.loc应用到DataFrame

df.loc[0:2, 'b'] = 'Test'
df

    a   b
0   1   Test
1   2   Test
2   3   Test
3   4   NA

以您的数据为例

# Python indexing starts at 0, so row 1 = position 0
VA.loc[0:11, 'Exp Category'] = 'Travel & Entertainment'

希望对您有所帮助！

如何修改数据框中新创建的列的多个行范围？

How do I modify multiple range of rows for a newly created Column in my dataframe?

python

pandas

data-wrangling