python - Pandas fillna 抛出 ValueError : fill value must be in categories

Question

描述:这两个功能都是分类数据类型。我在相同的不同内核中使用了这段代码日期集工作正常，唯一的区别是功能位于 flote64 中。后来我将这些特征数据类型转换为分类因为数据集中的所有特征都代表类别。

下面是代码:

AM_train['product_category_2'].fillna('Unknown', inplace =True)
AM_train['city_development_index'].fillna('Missing', inplace =True)

Answer 1

使用Series.cat.add_categories首先添加类别:

AM_train['product_category_2'] = AM_train['product_category_2'].cat.add_categories('Unknown')
AM_train['product_category_2'].fillna('Unknown', inplace =True) 

AM_train['city_development_index'] = AM_train['city_development_index'].cat.add_categories('Missing')
AM_train['city_development_index'].fillna('Missing', inplace =True)

示例:

AM_train = pd.DataFrame({'product_category_2': pd.Categorical(['a','b',np.nan])})
AM_train['product_category_2'] = AM_train['product_category_2'].cat.add_categories('Unknown')
AM_train['product_category_2'].fillna('Unknown', inplace =True) 

print (AM_train)
  product_category_2
0                  a
1                  b
2            Unknown