python - 不支持的操作数类型 - : 'str' and 'int' in python

Question

任何人都可以帮我理解我哪里出了问题吗？

import os
import numpy as np
import pandas as pd
ctr_x = []
tl_list = []

df = pd.read_csv('ring_1_05_sam.csv')
ctr_x = df.iloc[8:12, 0:1]
ctr_y = df.iloc[8:12, 1:2]
ctr_x = (ctr_x.to_string(index=False, header=False))
ctr_y = (ctr_y.to_string(index=False, header=False))
tl_list.append((str(ctr_x - 30),str(ctr_y - 30)))

print(tl_list)

我收到错误:

Traceback (most recent call last):
File "annotation.py", line 9, in <module>
tl_list.append((str(ctr_x - 30),str(ctr_y - 30)))
TypeError: unsupported operand type(s) for -: 'str' and 'int'

正如评论中提到的:

我尝试将每个值减去 30 并存储在 tl_list[] 中。

Answer 1

I am trying to subtract each value by 30 and store in tl_list[].

字符串转换会分散注意力并且没有必要。您也不需要显式实例化并附加到列表。使用pd.Series.tolist相反:

res_x = (df.iloc[8:12, 0] - 30).tolist()
res_y = (df.iloc[8:12, 1] - 30).tolist()

res = [res_x, res_y]

或者结合您的操作并使用np.ndarray.tolist :

res = (df.iloc[8:12, 0:2] - 30).values.tolist()