替换从某一行开始的列

Question

Consider this example:

rates_frame = rates_frame[['new_date', 'new_time', 'open', 'high', 'low', 'close', 'tick_volume']]
rates_frame
rates_frame.head()

Which produces this output:

I want to replace values in column open starting from row 1 by values from column close starting from row 0.

Answer 1

You are looking for the shift function in pandas . This shifts the values in the particular column by a specified number of periods

All you need is this

rates_frame['open_new'] = rates_frame['close'].shift(1)

PS : From the perspective of the share market, I don't think you should do this. It's not necessary that the opening price of today is equal to the closing price of the previous day. You can look into topics like gap-up opening, gap-down opening and unchanged. Only in the latter case, what you are doing holds true.