如何使用字典过滤数据框

Question

假设我有一个数据框和一个像这样的字典：

df = pd.DataFrame({"letters": ["a","b","c","b","c"], "numbers": [1,2,3,1,2]})
correct_mapping={"a":1,"b":2,"c":3}

我要过滤没有正确映射的行。

我尝试了这个，但是失败了：

df[correct_mapping[df["letters"]] != df["numbers"]]
TypeError: 'Series' objects are mutable, thus they cannot be hashed

任何帮助将不胜感激。

预期输出：

  letters  numbers
3       b        1
4       c        2

Answer 1

与map比较：

df[df['letters'].map(correct_mapping) != df['numbers']]                                                                                   
  letters  numbers
3       b        1
4       c        2