python - 如何使用 Python 将所有列从数字转换为分类

Question

我的 .csv 文件中有 51 列，我需要一次性将所有 int 64 数据类型转换为分类数据类型。我该怎么做？我是否需要提及 data[].

中的所有列名

 data[].astype('categorical')

Answer 1

您可以将列名放入列表中，然后循环更改每一列的类型。

import pandas as pd
import numpy as np

# create example dataframe
cats = ['A', 'B', 'C', 'D', 'E']

int_matrix = np.random.randint(10, size=(7,5))

df = pd.DataFrame(data = int_matrix, columns=cats)

print("Original example data\n")
print(df)
print(df.dtypes)

# get column names of data frame in a list
col_names = list(df)
print("\nNames of dataframe columns")
print(col_names)

# loop to change each column to category type
for col in col_names:
    df[col] = df[col].astype('category',copy=False)

print("\nExample data changed to category type")
print(df)
print(df.dtypes)

这个小程序的输出是:

Original example data

   A  B  C  D  E
0  0  4  9  2  9
1  2  5  2  4  1
2  1  1  0  5  7
3  1  2  5  4  0
4  9  2  6  5  3
5  3  3  2  1  7
6  6  0  8  7  3
A    int32
B    int32
C    int32
D    int32
E    int32
dtype: object

Names of dataframe columns
['A', 'B', 'C', 'D', 'E']

Example data changed to category type
   A  B  C  D  E
0  0  4  9  2  9
1  2  5  2  4  1
2  1  1  0  5  7
3  1  2  5  4  0
4  9  2  6  5  3
5  3  3  2  1  7
6  6  0  8  7  3
A    category
B    category
C    category
D    category
E    category
dtype: object