python处理一个csv数据，根据其中一列数据来得到新一列写入同一个文件中

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利用lambda函数

import pandas  as pd
import matplotlib.pyplot as plt
from matplotlib.dates import datestr2num,DateFormatter
import matplotlib.dates as dates

path = './info/info_left.csv'
path2 = './info/info_right.csv'
source_path = 'one_20axyz.csv'

if __name__ == '__main__':   
    msg = pd.read_csv(path,index_col=0)
#     msg = msg.sort_index()
    
#     print(len(msg['a_var'])/60,len(msg[msg['a_var'] > 0.025])/60)#时间段内的静止时间  运动时间
    msg['state'] = msg['a_var'].map(lambda x: 1 if x > 0.025 else -1)
    msg.to_csv(path)