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OPS445 Reference Sheet For Assessments

  • Note: words in (these) indicate a thing you will have to write, the parentheses are not part of the syntax.
  • Note: variable placeholders will use x, y, and so on.

First Quiz​

Shebang​

#!/usr/bin/env python3

Built-in Functions​

  • help()
  • type()
  • print()
  • input()
  • int()
  • str()
  • float()
  • len()
  • round()

Conditions​

if (condition):
    (action1)
elif (condition2):
    (action2)
else:
    (action)

Loops​

while (condition1):
    (action)
    if (condition2):
        break
for x in y:
    (action)
for i in range(x, y):
    (action)

Command Line Arguments​

import sys

sys.argv

Import Keywords​

  • from (module) import (something)
  • import (module) as (alias)

Comparison Operators​

Col 1Col 2
<>
<=>=
==!=

Logical Operators​

  • and
  • or
  • not

Math Operators​

Col 1Col 2
+-
***
///
+=-=
*=/=
%

Boolean Keywords​

  • True
  • False
  • None

Second Quiz​

Functions​

def func_name(x='Default value'):
    return y

Main Block​

if __name__ == "__main__":

Shell Commands​

os.system('x')
os.popen('x').read()
p = subprocess.Popen(['x'], stdout=subprocess.PIPE, stdin=subprocess.PIPE, stderr=subprocess.PIPE, shell=True)
s = p.communicate()
s[0].decode('utf-8')

Lists​

x = []
x.append(x)
x.insert(x, y)
x.remove(x)
x.sort()
x.pop()

y in x

Tuples​

x = (y, )
x = (y, z)

Sets​

x = {x, y}
x.add(x)
x = {}
y = {}
x & y
x - y
x ^ y
x | y

Dictionaries​

x = {y: z, a: b}
x[y] = z

x.keys()
x.values()
x.items()

Slicing​

x = 'PYTHON'
x[:z]
x[y:]
x[y:z]

Strings​

  • upper()
  • lower()
  • strip()
  • split()
  • join()
  • center()
  • replace()
  • startswith()

Third Quiz​

File Operations​

f = open(filename, operation_flag)

File Object Methods​

  • read
  • write
  • readline
  • readlines
  • close

Exception Handling​

try:
    ...
except (error1, error2):
    ...
except error3:
    ...
except:
    ...

Common Exceptions​

  • NameError
  • SyntaxError
  • IndexError
  • ValueError
  • FileNotFoundError
  • KeyError

Fourth Quiz​

F-Strings​

print(f'Hello World')
x = 'John'
print(f'Hello {x}')

y = 3
print(f'Formatted: {y:02d} minutes.')

Classes​

class Name:

    def __init__(self, x, y):
        self.x = x
        self.y = y

    def method(self):
        ...


n1 = Name(x, y)

Magic Methods​

class Name:

    def __eq__(self, other):
        return self == other

Equality Operators​

  • __eq__
  • __ne__
  • __gt__
  • __lt__
  • __ge__
  • __le__

Math Operators​

  • __add__
  • __sub__
  • __mul__
  • __truediv__
  • __mod__
  • __floordiv__
  • __pow__

Other Dunders​

  • __len__
  • __str__
  • __repr__