Grab every 4th row in data

mudassar031

I want to grab every 4th row in data without resampling in backtrader as i have done in python here is code

ts = TimeSeries(key='av_api_key', output_format='pandas')
data, meta_data = ts.get_intraday(symbol='MSFT', interval='60min', outputsize='full')
# Convert the index to datetime.
data.index = pd.to_datetime(data.index)
data.columns = ['Open', 'High', 'Low', 'Close', 'Volume']
# Grabs every 4th row
data = data.iloc[::4, :]

mudassar031

@mudassar031
if we have minutes of data and use resampling with compression=60 so backtrader give us data after averaging 60 mins actually i want to skip data in between and want to grab specific row as i have explained above example Thanks

run-out

@mudassar031 said in Grab every 4th row in data:

I want to grab every 4th row in data

What does it mean to 'grab' every fourth row. What will you be doing with it? It might be easier to just have a counter in next and only consider every fourth row?

mudassar031

@run-out
can you please give me an code example to consider every fourth row in next function?

ab_trader

Try this

def next(self):
    if len(self.data) % 4 != 0:
        return

    # operations you want to make on every 4th bar

mudassar031

@ab_trader
Thanks

mudassar031

@ab_trader
i have minutes of data and i want to fetch 4 hours our data but it always executing one minutes on data i want only to display row after 240th row

     if len(self.data) % 240 != 0:

        self.log(
            'Open: %.2f '
            'High: %.2f '
            'Low: %.2f '
            'Close: %.2f '
            % (
                self.data.open[0],
                self.data.high[0],
                self.data.low[0],
                self.data.close[0]
            ))

mudassar031

@ab_trader
another question i am using 4 hours of resampledata

 data0 = DataFactory(
        dataname=args.symbol or "MSFT",
        timeframe=bt.TimeFrame.TFrame("Minutes"),
        fromdate=pd.Timestamp('2020-07-27'),
        todate=pd.Timestamp('2020-07-29'),
        compression=1,
        historical=True)
    cerebro.adddata(data0)

    cerebro.resampledata(data0, timeframe=bt.TimeFrame.Minutes, compression=60 * 4)

and i am fetching 4 hours resample data in def init(self):
like this

self.data4h = self.datas[1]  # 240 minute resampled data

its giving me error

File "4hresample.py", line 74, in __init__
    self.data4h = self.datas[1]  # 240 minute resampled data
IndexError: list index out of range

mudassar031

@mudassar031
I have resolved it actually
this must be

if len(self.data) % 240 == 0:

Thanks