Category: Python Answers

Sometimes, we want to get an absolute file path in Python.

In this article, we’ll look at how to get an absolute file path in Python.

How to get an absolute file path in Python?

To get an absolute file path in Python, we can use the os.path.abspath method.

For instance, we write

import os

p =  os.path.abspath("mydir/myfile.txt")

to call os.path.abspath with a relative path.

And then the absolute path equivalent of the relative path is returned.

Conclusion

To get an absolute file path in Python, we can use the os.path.abspath method.

Sometimes, we want to add function overloading with Python.

In this article, we’ll look at how to add function overloading with Python.

How to add function overloading with Python?

To add function overloading with Python, we can replace overloading with making parameters optional.

For instance, we write

class Character(object):
    # ...

    def add_bullet(self, sprite=default, start=default, 
                 direction=default, speed=default, accel=default, 
                  curve=default):
        # ...

to add the add_bullet method that has the all the parameters made optional by setting their default value to default.

Then we can call add_bullet without passing in all the arguments.

Conclusion

To add function overloading with Python, we can replace overloading with making parameters optional.

Sometimes, we want to create a constant in Python.

In this article, we’ll look at how to create a constant in Python.

How to create a constant in Python?

To create a constant in Python, we can use the typing.Final property.

For instance, we write

from typing import Final

a: Final = 1

to set variable a to the Final type.

This will be checked by static type checkers to see if a has been reassigned.

But it doesn’t prevent reassignment at run time.

Conclusion

To create a constant in Python, we can use the typing.Final property.

Sometimes, we want to fix TypeError: unsupported operand type(s) for -: ‘str’ and ‘int’ when using Python input

In this article, we’ll look at how to fix TypeError: unsupported operand type(s) for -: ‘str’ and ‘int’ when using Python input.

How to fix TypeError: unsupported operand type(s) for -: ‘str’ and ‘int’ when using Python input?

To fix TypeError: unsupported operand type(s) for -: ‘str’ and ‘int’ when using Python input, we should convert the string returned by input to an int.

For instance, we write

def cat_n_times(s, n):
    for i in range(n):
        print(s) 

text = input("What would you like the computer to repeat back to you: ")
num = int(input("How many times: "))

cat_n_times(text, num)

We call input with a string for the prompt.

And then we call input to get the number entered by the user.

Next, we call int to convert the string of the value entered by the user to an int.

Then we can use value n in cat_n_times as an argument of range`.

Conclusion

To fix TypeError: unsupported operand type(s) for -: ‘str’ and ‘int’ when using Python input, we should convert the string returned by input to an int.

Sometimes, we want to write to a Python subprocess’ stdin.

In this article, we’ll look at how to write to a Python subprocess’ stdin.

How to write to a Python subprocess’ stdin?

To write to a Python subprocess’ stdin, we can use the communicate method.

For instance, we write

from subprocess import Popen, PIPE, STDOUT

p = Popen(['myapp'], stdout=PIPE, stdin=PIPE, stderr=PIPE)
stdout_data = p.communicate(input='data_to_write')[0]

to call Popen with the command we want to run in a list.

And we set stdout , stdin, and stderr all to PIPE to pipe them to their default locations.

Next, we call p.communicate with the input argument set to the string we want to write to stdin.

Conclusion

To write to a Python subprocess’ stdin, we can use the communicate method.