Python >> Tips and Tricks 3
Table of Contents
This tutorial will explain how to use virtual environment, absolute import and relative import, get absolute path of file, use argparse module, use set(), use range, get all files in a folder.
Python how to use virtual environment
What is Python virtual environment
Python virtual environment is a isolated environment where you can install and run Python program.
How to install Python virtual environment
# Install Python virtual environment
pip install virtualenv
How to create Python virtual environment
# Create Python virtual environment
virtualenv -p python3 myenv
How to activate Python virtual environment
# Activate Python virtual environment
source myenv/bin/activate
How to deactivate Python virtual environment
# Deactivate Python virtual environment
deactivate
Python how to absolute import and relative import
Absolute import
# absolute import
from pkg1.pkg2.mymodule1 import func2
Relative import
# relative import
from .mymodule2 import func2
Python how to get absolute path of file
Use os.path module to get absolute path of file
# Get absolute path of file
import os
print(os.path.abspath('test.txt'))
d:\myfolder\test.txt
Use pathlib module to get absolute path of file
# Get absolute path of file
import pathlib
print(pathlib.Path('test.txt').resolve())
d:\myfolder\test.txt
Use path module to get absolute path of file
# Get absolute path of file
import path
print(path.Path('test.txt').abspath())
Python how to use argparse module
Create command line argument parser
# Create command line argument parser
import argparse
parser = argparse.ArgumentParser(description='This is a command line argument parser')
parser.add_argument('-a', '--arg1', help='This is argument 1')
parser.add_argument('-b', '--arg2', help='This is argument 2')
parser.add_argument('-c', '--arg3', help='This is argument 3')
args = parser.parse_args()
print(args.arg1)
print(args.arg2)
print(args.arg3)
Save the code above to test.py
python test.py -a 1 -b 2 -c 3
1
2
3
Python how to use set
Create set
# Create set
my_set = set()
my_set.add(1)
my_set.add(2)
my_set.add(3)
print(my_set)
{1, 2, 3}
Add element to set
# Add element to set
my_set.add(4)
print(my_set)
{1, 2, 3, 4}
Remove element from set
# Remove element from set
my_set.remove(3)
print(my_set)
{1, 2, 4}
Use set() to remove duplicate element from list
# Use set() to remove duplicate element from list
my_list = [1, 2, 3, 4, 5, 6, 7, 8, 9, 1, 2, 3, 4, 5, 6, 7, 8, 9]
my_set = set(my_list)
print(my_set)
{1, 2, 3, 4, 5, 6, 7, 8, 9}
Python how to use range
Create range from 0 and loop it
# Create a range from 0 to 9 and loop it
my_range = range(10)
for i in my_range:
print(i)
0
1
2
3
4
5
6
7
8
9
Create range from 1 and loop it
# Create range
my_range = range(1, 11)
for i in my_range:
print(i)
1
2
3
4
5
6
7
8
9
10
Create range and loop it with step
# Create range
my_range = range(1, 11, 2)
for i in my_range:
print(i)
1
3
5
7
9
Python how to get all files in a folder
Use os.walk to get all files in a folder
# Use os.walk to get all files in a folder
import os
for root, dirs, files in os.walk(r'D:\temp'):
for file in files:
print(os.path.join(root, file))
Use glob module to get all files in a folder
# Use glob module to get all files in a folder
import glob
for file in glob.glob(r'D:\test\*.txt'):
print(file)
D:\test\test2.txt
D:\test\test4.txt
Use os.listdir to get all files in a folder
# Use os.listdir to get all files in a folder
import os
for file in os.listdir(r'D:\test'):
print(file)
Not only files but also folders
folder1
folder2
test2.txt
test4.txt
We can use isfile() to check if the file is a file or not
# Use os.listdir to get all files in a folder
import os
for file in os.listdir(r'D:\test'):
if os.path.isfile(os.path.join(r'D:\test', file)):
print(file)
test2.txt
test4.txt