Question

我是熊猫的新手...我正在尝试向df（df ['new_col']）添加一个新的列。但是当我出现此错误时：

import requests
import pandas as pd
import json

res = requests.get("http://api.etherscan.io/api?module=account&action=txlist&address=0xddbd2b932c763ba5b1b7ae3b362eac3e8d40121a&startblock=0&endblock=99999999&sort=asc&apikey=YourApiKeyToken")
j = res.json()
df = pd.DataFrame(j['result'])
#add column
df = df['new_col'] = '12'
print(df.head())

Traceback (most recent call last):
  File "pandas_csv.py", line 8, in <module>
    df = df['new_col'] = '12'
TypeError: 'str' object does not support item assignment

有什么想法吗？

Answer 1

只需更换

df = df['new_col'] = '12'

作者

df['new_col'] = '12'

Answer 2

仅是为了解释为什么会发生这种情况，下面是该问题的一个更简单的MCVE：

d = {1: "a"}
d = d[1] = "3"

TypeError: 'str' object does not support item assignment

发生这种情况是因为，如here所述，df = df['new_col'] = '12'等同于：

df = "3"
df['new_col'] = '12'

现在，很明显为什么会发生错误。在df分配发生之前，'new_col'被字符串覆盖。

TypeError：'str'对象不支持项目分配熊猫添加列

2 个答案: