区分 pandas dataframe 中的十进制和字符串列

Question

I need to identify which columns in a dataframe are decimals and which are strings.
Using df.dtypes gives 'object' for both column types:

import pandas as pd
import decimal 

data = {'dec1': [1.1, 1.2],'str1': ["a","b"]}
df = pd.DataFrame(data)

df.dec1 = df.dec1.apply(lambda x: decimal.Decimal(x))

df.dtypes

I am using the following code to know which are decimals, but there has to be a more pythonic way for something so basic. What is it?

actual_col_types = df.iloc[0].apply(type)

df_decimals = df.loc[:,actual_col_types==decimal.Decimal]

Answer 1

Use isinstance , what should be more preferable like type, link :

mask = df.iloc[0].map(lambda x: isinstance(x, decimal.Decimal))
df_decimals = df.loc[:,mask]
print (df_decimals)
                                                dec1
0  1.10000000000000008881784197001252323389053344...
1  1.19999999999999995559107901499373838305473327...