np.argmax不返回正确的索引

Question

我使用np.argmax搜索此数组最高值的索引

它返回720.它应该是721.我试图谷歌问题，但还没有找到解决方案。

这是我的代码：

import pandas as pd
import numpy as np
import matplotlib.pylab as plt
from matplotlib.pylab import rcParams
from statsmodels.tsa.stattools import acf, pacf

dir='C:\\Users\\DELL\\Google Drive\\JVN couse materials\\Projects\\Practice projects\\Time series project\\energydata_complete.csv'
rawdata=pd.read_csv(dir, index_col='date')
timeseries=pd.DataFrame(rawdata['Appliances'])
timeseries.index=pd.to_datetime(timeseries.index)
timeseries['Log scale']=np.log10(timeseries['Appliances'])
lag_pacf = pacf(timeseries.loc['2016-01-12':'2016-01-21','Log scale'], nlags=1439, method='ols')
highest_pacf_lag=np.argmax(lag_pacf[1:]) ###this is where the problem happens