You can use the history() function to compare prices across current and previous bars in minute-mode simulation. There are a few different ways you can implement the logic, if you want to compare the current price to yesterday's close price you can follow this example right out of the help docs:
def handle_data(context, data):
price_history = history(bar_count=2, frequency='1d', field='price')
for s in data:
prev_bar = price_history[s][-2]
curr_bar = price_history[s][-1]
if curr_bar > prev_bar:
The history() function returns a dataframe of historical prices and dates that you can index into to grab the data you want. So in that example price_history[s][-1] is the most recent price for stock 's' and price_history[s][-2] is the price before that one (i.e. yesterday's close).
If you have a simple algo you are trying to get working with this logic feel free to post it and I'd be happy to try to help you debug it.
Best wishes, Jess
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