在Pandas中将列转换为字符串

I have the following DataFrame from a SQL query:

我有一个SQL查询的以下DataFrame：

(Pdb) pp total_rows
     ColumnID  RespondentCount
0          -1                2
1  3030096843                1
2  3030096845                1

and I want to pivot it like this:

我想像这样转动它：

total_data = total_rows.pivot_table(cols=['ColumnID'])

(Pdb) pp total_data
ColumnID         -1            3030096843   3030096845
RespondentCount            2            1            1

[1 rows x 3 columns]


total_rows.pivot_table(cols=['ColumnID']).to_dict('records')[0]

{3030096843: 1, 3030096845: 1, -1: 2}

but I want to make sure the 303 columns are casted as strings instead of integers so that I get this:

但我想确保将303列作为字符串而不是整数进行转换，以便我得到：

{'3030096843': 1, '3030096845': 1, -1: 2}

2 个解决方案

#1

143

One way to convert to string is to use astype:

转换为字符串的一种方法是使用astype：

total_rows['ColumnID'] = total_rows['ColumnID'].astype(str)

However, perhaps you are looking for the to_json function, which will convert keys to valid json (and therefore your keys to strings):

但是，也许你正在寻找to_json函数，它将键转换为有效的json（因此你的键到字符串）：

In [11]: df = pd.DataFrame([['A', 2], ['A', 4], ['B', 6]])

In [12]: df.to_json()
Out[12]: '{"0":{"0":"A","1":"A","2":"B"},"1":{"0":2,"1":4,"2":6}}'

In [13]: df[0].to_json()
Out[13]: '{"0":"A","1":"A","2":"B"}'

Note: you can pass in a buffer/file to save this to, along with some other options...

注意：你可以传入一个缓冲区/文件来保存它，以及其他一些选项......

#2

Here's the other one, particularly useful to convert the multiple columns to string instead of just single column:

这是另一个，特别适用于将多列转换为字符串而不是单列：

In [76]: import numpy as np
In [77]: import pandas as pd
In [78]: df = pd.DataFrame({
    ...:     'A': [20, 30.0, np.nan],
    ...:     'B': ["a45a", "a3", "b1"],
    ...:     'C': [10, 5, np.nan]})
    ...: 

In [79]: df.dtypes ## Current datatype
Out[79]: 
A    float64
B     object
C    float64
dtype: object

## Multiple columns string conversion
In [80]: df[["A", "C"]] = df[["A", "C"]].astype(str) 

In [81]: df.dtypes ## Updated datatype after string conversion
Out[81]: 
A    object
B    object
C    object
dtype: object

#1

143