10 python tips and tricks for writing better code
10 python tips and tricks for writing better code
1. condition
eg-1
condition = True
if condition:
x = 1
else:
x = 0
print (x)
a better code for eg-1:
condition = True
x = 1 if condition else 0
print (x)
2. numbers
eg-2.1
num1 = 100000000000
num2 = 1000000000
total = num1 + num2
print (total)
a better code :
num1 = 100_000_000_000
num2 = 1_000_000_000
total = num1 + num2
print (total)
it’s better ,cuz it’s easier to read and compare the numbers.
eg-2.2
format a number.
num3 = 100000000000
num4 = 1_000_000_000
print(f'{num3:,}')
print(f'{num4:,}')
the output is:
100,000,000,000
1,000,000,000
3. file
eg-3
f = open('test.txt','r')
file_contents = f.read()
f.close()
words = file_contents.split(' ')
word_count = len(words)
print(word_count)
a better code is:
with open('test.txt','r') as f:
file_contents = f.read()
words = file_contents.split(' ')
word_count = len(words)
print(word_count)
this will make the “content manager” to manage the file,it’s easier to write and looks more simpler.
4. loop
eg-4.1
names = ['Corey','Chris','Dave','Travis']
index = 0
for name in names:
print(index,name)
index += 1
a better code is:
names = ['Corey','Chris','Dave','Travis']
index = 0
for index,name in enumerate(names):
print(index,name)
the outpus is:
0 Corey
1 Chris
2 Dave
3 Travis
eg-4.2
if you want to start at a specific index:
names = ['Corey','Chris','Dave','Travis']
index = 0
for index,name in enumerate(names,start=1):
print(index,name)
the output is:
1 Corey
2 Chris
3 Dave
4 Travis
5. zip
zip means loop two lists as one.
eg-5.1
names = ['Peter Parker','Clark Kent','Wade Wilson','Bruce Wayne']
heroes = ['Spiderman','Superman','Deadpool','Batman']
for index,name in enumerate(names):
hero = heroes[index]
print(f'{name} is actually {hero}')
the output is:
Peter Parker is actually Spiderman
Clark Kent is actually Superman
Wade Wilson is actually Deadpool
Bruce Wayne is actually Batman
a better code is:
names = ['Peter Parker','Clark Kent','Wade Wilson','Bruce Wayne']
heroes = ['Spiderman','Superman','Deadpool','Batman']
for name,hero in zip(names,heroes):
print(f'{name} is actually {hero}')
eg-5.2
if loop three lists to one:
names = ['Peter Parker','Clark Kent','Wade Wilson','Bruce Wayne']
heroes = ['Spiderman','Superman','Deadpool','Batman']
universes = ['Marvel','DC','Marvel','DC']
for name,hero,universe in zip(names,heroes,universes):
print(f'{name} is actually {hero} from {universe}')
the output is:
Peter Parker is actually Spiderman from Marvel
Clark Kent is actually Superman from DC
Wade Wilson is actually Deadpool from Marvel
Bruce Wayne is actually Batman from DC
eg-5.3
print the zip instead access each element:
names = ['Peter Parker','Clark Kent','Wade Wilson','Bruce Wayne']
heroes = ['Spiderman','Superman','Deadpool','Batman']
universes = ['Marvel','DC','Marvel','DC']
for value in zip(names,heroes,universes):
print(value)
the output is:
'Peter Parker', 'Spiderman', 'Marvel')
('Clark Kent', 'Superman', 'DC')
('Wade Wilson', 'Deadpool', 'Marvel')
('Bruce Wayne', 'Batman', 'DC')
eg-5.4
the same as eg-5.3:
names = ['Peter Parker','Clark Kent','Wade Wilson','Bruce Wayne']
heroes = ['Spiderman','Superman','Deadpool','Batman']
universes = ['Marvel','DC','Marvel','DC']
for value in zip(names,heroes,universes):
print(value)
print(value[0])
print(value[1])
print(value[2])
the output is:
('Peter Parker', 'Spiderman', 'Marvel')
Peter Parker
Spiderman
Marvel
('Clark Kent', 'Superman', 'DC')
Clark Kent
Superman
DC
('Wade Wilson', 'Deadpool', 'Marvel')
Wade Wilson
Deadpool
Marvel
('Bruce Wayne', 'Batman', 'DC')
Bruce Wayne
Batman
DC
6. packing/unpacking
eg-6.1
a, b = (1, 2)
print(a)
print(b)
the output is :
1
2
eg-6.2
if you just want variable “a” and you dont want “b”,so we can make “b” unuse by underline:
a, _ = (1, 2)
print(a)
#print(b)
eg-6.3.1
a, b, *c = (1, 2, 3, 4, 5)
print(a)
print(b)
print(c)
the output is:
1
2
[3, 4, 5]
the “*c” means everything after a and b.
eg-6.3.2
a, b, *_ = (1, 2, 3, 4, 5)
print(a)
print(b)
#print(c)
the output is:
1
2
the symbol “_” makes the value unuse.
eg-6.3.3
a, b, *c, d = (1, 2, 3, 4, 5, 6, 7)
print(a)
print(b)
print(c)
print(d)
the output is:
1
2
[3, 4, 5, 6]
7
eg-6.3.4
a, b, *_, d = (1, 2, 3, 4, 5, 6, 7)
print(a)
print(b)
#print(c)
print(d)
the output is:
1
2
7
7. get/set attributes for object
eg-7.1
class Person():
pass
person = Person()
person.first = "Corey"
person.last = "Schafer"
print(person.first)
print(person.last)
the output is :
Corey
Schafer
if we use setattr/getattr method:
class Person():
pass
person = Person()
first_key = 'first'
first_val = 'Corey'
setattr(person, first_key, first_val)
first = getattr(person, first_key)
print(first)
the output is :
Corey
eg-7.2
if more key-values,loop them:
class Person():
pass
person = Person()
person_info = {'first':'Corey','last':'Schafer','age':'35','number':'13883887654','address':'beijing'}
for key,value in person_info.items():
setattr(person, key, value)
for key in person_info.keys():
print(getattr(person, key))
the output is :
Corey
Schafer
35
13883887654
beijing
8. input secret information
eg-8
username = input('please input Username: ')
password = input('please input Password: ')
print('Logging In...')
when you run it and input the password, the passwrod is plaintext:
please input Username: vimmer
please input Password: mypassword
a better code is:
from getpass import getpass
username = input('please input Username: ')
password = getpass('please input Password: ')
print('Logging In...')
this time, the password will not be a plaintext.
9. env
python -m venv myvenv
10. module
the command :
python test.py
is equal to:
python -m test
“-m” means module name.
eg-10.1
python -m smtpd -c DebuggingServer -n localhost:1025
how we know “-c” or “-n” options?
use python terminal to get help,like these commands:
user@ipp:~/home/$ python
Python 3.6.9 (default, Apr 18 2020, 01:56:04)
[GCC 8.4.0] on linux
Type "help", "copyright", "credits" or "license" for more information.
>> import smtpd
>> help(smtpd)
then a manu page will show in the terminal,you can see “-c” or “-n” options and explaintions.
eg-10.2
antother example:
user@ipp:~/home/$ python
Python 3.6.9 (default, Apr 18 2020, 01:56:04)
[GCC 8.4.0] on linux
Type "help", "copyright", "credits" or "license" for more information.
>>> from datatime import datetime
>>> dir(datetime)
>>> datetime.today
>>> exit()