How to write to a file by using (or changing) print using Python 3.x

Question

Im using an API from Interactive Brokers to get historical data and I am using their code to download the data.

The code uses the print function to output the data to the terminal, but I would like to redirect it to a file (lets call that file StockData.txt)

The code I am using is:

from ibapi.client import EClient
from ibapi.wrapper import EWrapper
from ibapi.contract import Contract

class TestApp(EWrapper, EClient):
    def __init__(self):
        EClient.__init__(self, self)

    def error(self, reqId, errorCode, errorString):
        print("error: ", reqId, " ", errorCode, " ", errorString)

    def historicalData(self, reqId, bar):
        print("HistoricalData. ", reqId, " Date:", bar.date, "Open:", bar.open, "High:", bar.high, "Low:", bar.low, "Close:", bar.close, "Volume:", bar.volume)

def main():
    app = TestApp()

    app.connect("127.0.0.1", 7497, 0)

    contract = Contract ()
    contract.symbol = "AAPL"
    contract.secType = "STK"
    contract.exchange = "SMART"
    contract.currency = "USD"
    contract.primaryExchange = "NASDAQ"

    app.reqHistoricalData(0, contract, "", "1 D", "1 min", "TRADES", 0, 1, False, [])

    app.run()

if __name__ == "__main__":
    main()

Like I said, I would like the API to write to StockData.txt, but I am unsure how to do this since it's not my code and I am not that savvy in Python.

Could anyone help me out here? Thanks!

Why not just using standard OS output redirection instead of modifying the script? For how to do that on windows, check this question: https://stackoverflow.com/questions/1420965/redirect-windows-cmd-stdout-and-stderr-to-a-single-file — GPhilo, May 07 '19 at 08:26
Hi GPhilo, I am unsure what you mean by that. Could you clarify please? — Hoogoo, May 07 '19 at 08:28
GPhilo, thank you for the append, but I am not able to use that form for my problem. — Hoogoo, May 07 '19 at 08:36
Perhaps more info on why you're not able may help us helping you to solve te issue. Can you clrify? — GPhilo, May 07 '19 at 08:37
The link you send does not talk about printing or writing, but redirecting something with a line of code. i don't think I can use that code — Hoogoo, May 07 '19 at 08:44

Nullman · Accepted Answer · 2019-05-07T08:50:39.747

1

while it would probably be better to do output redirection:

python my_script.py > outputfile.txt

to actually overwrite any function is pretty simple:

def print_to_file(*args):
    with open('text.txt', 'a') as fh:
        fh.write(' '.join(map(str,args)))
print = print_to_file

just plop the above lines of code somewhere high in you script
this is not the recommended way though, because it will only overwrite print in the current script and not in the imported modules which may also be printing

A better way is to change your stdout:

import sys
sys.stdout = open('text.txt', 'a')

edited May 07 '19 at 08:50

answered May 07 '19 at 08:45

Nullman

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First option (overwriting print) only works for the printing done in the current script: if any of the imported modules writes to the terminal, that part won't be written to file. The correct way (aside from the redirection) is to change `stdout` – GPhilo May 07 '19 at 08:48

How to write to a file by using (or changing) print using Python 3.x

1 Answers1