pandas时间处理

#导入numpy,pandas包
import numpy as np
import pandas as  pd
#读取csv文件
df = pd.read_csv('aa.csv',names = ['time', 'values'],header = None, sep = ",")
df.head()

#时间字符串切分
df['new_time'] = df['time'].apply(lambda x:x[0:19])
#字符串转时间
df['new_time'] = df['new_time'].apply(lambda x:datetime.datetime.strptime(x, '%Y-%m-%d %H:%M:%S'))
#或
df['new_time'] = pd.to_datetime(df.new_time)

df_A027['time_1'] =df_A027['new_time'].shift(1)
df_A027['diff'] = df_A027['new_time'] - df_A027['time_1']
df_A027['val'] = df_A027['diff']/np.timedelta64(1, 's')
df_A027.head()

df_A027['time_2'] =df_A027['new_time'][0]
df_A027['diff'] = df_A027['new_time'] - df_A027['time_2']
df_A027['val2'] = df_A027['diff']/np.timedelta64(1, 's')