category_backend.py

## Convert Food_Category to the category-dtype and check backend codes ## 
dairy_table['Food_Category'].astype('category').cat.codes

Out[97]: 
index0     1
index1     3
index2     1
index3     1
index4     1
......
dtype: int8

## Check the memory usage 
object_mem = dairy_table['Food_Category'].memory_usage(index=False, deep=True)
category_mem = dairy_table['Food_Category'].astype('category').memory_usage(index=False, deep=True)
print(f'Total bytes for the object-dtype = {object_mem}\nTotal bytes for the category-dtype = {category_mem}')

Total bytes for the object-dtype = 1051
Total bytes for the category-dtype = 427