Defining Data Type during csv file import based on column index in pandas

Question

I need to import a csv file that has 300+ columns, among these columns, only the first column needs to specified as a category, while the rest of the columns should be float

Answer 1

read it twice, first time get all the columns, second time, specify dtype when reading.

import pandas as pd
import numpy as np
df = pd.DataFrame(np.random.randint(0,100,size=(100, 4)), columns=list('ABCD'))
df.to_csv('tmp.csv',index=False)

path = 'tmp.csv'
df =pd.read_csv(path)
type_dict = {}

for key in df.columns:
    if key == 'A':
        type_dict[key]='category'
    else:
        type_dict[key]=np.float32
df = pd.read_csv(path,dtype=type_dict)
print(df.dtypes)