'str'和'int'的实例之间不支持'<='

Question

以下是我读取CSV文件的代码，但出错了我的代码有什么问题。

df2 = pd.read_csv(img_category_path, delim_whitespace= True,  header=0, names=['category'], low_memory=False )


df['upper_lower'] = ['1' if  i < 21 else '3' if   i > 36  else  '2' for i in df2['category']]

在我添加low_memory= False时仍然出现错误

TypeError                                 Traceback (most recent call last)
<ipython-input-146-e50367d03a63> in <module>
----> 1 df['upper_lower'] = ['1' if  i < 21 else '3' if   i > 36  else  '2' for i in df2['category']]

<ipython-input-146-e50367d03a63> in <listcomp>(.0)
----> 1 df['upper_lower'] = ['1' if  i < 21 else '3' if   i > 36  else  '2' for i in df2['category']]

TypeError: '<' not supported between instances of 'str' and 'int'

df2 = pd.read_csv(img_category_path, delim_whitespace= True,  header=0, names=['category'], low_memory=False )

df['upper_lower'] = ['1' if  i < 21 else '3' if   i > 36  else  '2' for i in df2['category']]

过滤文件以获得准确的结果

Answer 1

您可以通过以下方法解决问题：

df['upper_lower'] = ['1' if  i < 21 else '3' if   i > 36  else  '2' for i in df2['category']]

收件人：

df['upper_lower'] = ['1' if  int(i) < 21 else '3' if int(i) > 36  else  '2' for i in df2['category']]

出现问题（如注释中所指出的）是因为您从CSV文件中加载了表示数字的字符串，并且需要在比较之前将它们转换为int（您的i变量和{{1 }}系列的类型为df2["category"]。