python入门系列(14): python对字符串型数据处理

1. sklearn包

1.1 labelEncoder

from sklearn import preprocessing
le = preprocessing.LabelEncoder()
le.fit(df['Col1'])
df['Col3'] = le.transform(df['Col3'])

再来一个示例

###
from sklearn import preprocessing
from sklearn.preprocessing import LabelEncoder

le = preprocessing.LabelEncoder()
le.fit(["paris", "paris", "tokyo", "amsterdam"])
LabelEncoder()

print(list(le.classes_))

# ['amsterdam', 'paris', 'tokyo']

print(le.transform(["tokyo", "tokyo", "paris"])) 

# array([2, 2, 1])

这里结合读取文件，来实现字符编码。

import numpy as np
import pandas as pd
import xlrd
from tqdm import tqdm

from sklearn import preprocessing
from sklearn.preprocessing import LabelEncoder

#### obtain cols of XX type
def obtain_x(train_df,xtype):
	dtype_df = train_df.dtypes.reset_index()
	print('dtype_df\n',dtype_df)
	dtype_df.columns = ['col','type']
	return dtype_df[dtype_df.type==xtype].col.values


train_df = pd.read_excel(r'G:\test_onehot.xlsx')
# print('train_df',train_df)

# obtain str cols
str_col = obtain_x(train_df,'object')#获得字符串类型列代号

print('str_col\n',str_col)

str_col_list=str_col.tolist()
print('str_list\n',str_col_list)

# print('obtained float cols, and count:',len(float64_col))

print('train_df[str_col_list]\n',train_df[str_col_list])

###编码
le = preprocessing.LabelEncoder()
# list= [col for col in str_col ]

list=[]
# list=str_col_list

# list.append(train_df[col] for col in str_col_list)
list.append(train_df[str_col_list[0]])
list.append(train_df[str_col_list[1]])
	
print('list\n',list[1][0])
le.fit(list[0])
LabelEncoder()
print('le.transform(list[0])\n',le.transform(list[0]))

2. 使用pandas包处理

2.1 独热编码

import pandas as pd

train_df = pd.read_excel(r'G:\test_onehot.xlsx')
# print('train_df',train_df)
 
#get_dummies

# obtain str cols
str_col = obtain_x(train_df,'object')#获得字符串类型列代号

train_df_dummy=pd.get_dummies(train_df[str_col])
train_df=train_df.drop(str_col,axis=1)

train_df=train_df.join(train_df_dummy)

print('train_df\n',train_df)

---

参考：

1. pandas处理字符串型数据；
2. sklearn_labelEncoder;
3. 独热编码优快云；
4. 独热编码_GitHub；
5. 独热编码的两种实现方式panda和sklearn