python读取csv文件，选取特定的列，保存到新的文件，将csv数据转换为时间序列
import numpy as np
import pandas as pd
#read csv
data1 = pd.read_csv(r'tem.csv',sep=';',header='infer')
#select specific columns
data1 = pd.read_csv(r'tem.csv',sep=';',header='infer',usecols=[0,1,3])
#set column headers
data1.columns = ['y','m','number']
data2 = pd.read_csv(r'tem.csv',sep=';',header='infer',usecols=[3])
#Merge the first two columns, set the title to month
data1['Month'] = data1['y'].map(str)+'-'+data1['m'].map(str)
#Extract two columns of data1
data2 =data1.loc[:,['Month','number']]
#serve to new csv
data2.to_csv('new.csv')
data = pd.read_csv('ssn.csv', parse_dates=['Month'], index_col='Month')
ts = data['number'] #转换为时间序列数据
