为何以下代码第8行会出现TypeError: 'Float'对象不可迭代错误？

Hey there! Let's break down exactly why this error pops up when your code hits line 8.

错误核心定位 #

The error originates directly in your mapper lambda function:

mapper = lambda x: sum([ord(digit) for digit in x])

When this function runs, you’re trying to iterate over x (with for digit in x), but x is a Float object—and floats aren’t iterable. Unlike strings or lists, you can’t loop through a single floating-point number character by character.

为什么x会是浮点数？ #

Your code assumes any column with cardinality > 2 is a categorical column (filled with string values), but that’s not the case here. The column you’re processing actually contains floating-point numbers, not text. When x_train[column].apply(mapper) executes, it passes each float value from the column to x, and trying to loop over that float triggers the TypeError.

快速修复与优化建议 #

• 先转成字符串再处理: 修改mapper函数，先把浮点数转换成字符串，这样就能正常遍历字符了：

  mapper = lambda x: sum([ord(digit) for digit in str(x)])
  

• 校验列类型判断逻辑: 仔细检查高基数列是否真的是分类列。有些高基数列可能是连续数值型，这种ASCII码求和的处理方式对它们来说毫无意义。
• 修复列删除逻辑: 你当前的删除代码并没有真正从DataFrame中移除列，需要重新赋值或者使用inplace=True：

  # 方式1：重新赋值
  x_train = x_train.drop(column, axis=1)
  x_test = x_test.drop(column, axis=1)
  # 方式2：使用inplace参数
  x_train.drop(column, axis=1, inplace=True)
  x_test.drop(column, axis=1, inplace=True)
  

内容的提问来源于stack exchange，提问作者Monisha Arunkumar