Call a Python function that expects keyboard input with data from a text file

Question

Using a C/C++ analogy, I want to pipe the contents of a file to stdin.

I have a Python function that prompts users for student name and grade and creates a list of lists. Instead of typing a 100 names and grades, I want to put the names and grades in a text file and provide that as input to this function. How do I do this? Code fragment below:

def enter_grades(num_students):
    class_grades = []
    for i in range(num_students):
       class_grades.append([input(), float(input())])
    print( class_grades)
    return class_grades

There is a file "grades.txt" with student names and grades. Want to provide its contents as input to enter_grades().

I want to use the file to test the function with a lot of inputs. — Babar-Baig
– Babar-Baig, Commented Dec 30, 2017 at 1:35

Wray Zheng · Accepted Answer · 2017-12-30 01:48:33Z

2

You are finding the python version of freopen().

You can set the sys.stdin to a file object simply do the following:

import sys

sys.stdin = open("/path/to/file.txt", "r")
text = input()
print(text)

The input() function will now read data from file instead of user input.

More Usage

Similarly, if you want to redirect the standard output or standard error to a file, just set the corresponding variables in sys:

sys.stdout = open("stdout.txt", "w")
sys.stderr = open("stderr.txt", "w")

edited Dec 30, 2017 at 1:48

answered Dec 30, 2017 at 1:42

Wray Zheng

99711 silver badges18 bronze badges

Sign up to request clarification or add additional context in comments.

Collectives™ on Stack Overflow

Call a Python function that expects keyboard input with data from a text file

1 Answer 1

Comments

Your Answer

Hot Network Questions

Collectives™ on Stack Overflow

1 Answer 1

Comments

Your Answer

Sign up or log in

Post as a guest

Related