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Python Cheat Sheet by

hello
python

Vocabulary

variable
holds a value and can be changed
string
a list of characters such as numbers, letters, symbols
integer
whole number­/co­unting number. 100, -52
float
the number in decimal. 100.01, -52.5
boolean
true/false
modulo
find the remainder
syntax
gramma­r/s­tru­cture of language

Naming Conven­tions

Rules for naming variab­­les:
- letters
- numbers
- unders­­cores (_)
- can start with lett­­ers or unde­­rs­c­o­res ONLY
- NO SPACES

Valid names:
- _mystr
- my3
Hello_­­there

Invalid names:
- 3my= "­­hi­" -- cannot start with number
- first name = "­­hi­" -- no spaces allowed
- first­­-­name -- dashes are not accepted

Addition

string + string
combine together
string + number
CRASH!
number + number
addition (math)

Multip­lic­ation & Exponents

string * string
CRASH!!
string * number
combines the strings multiple time
number * number
math (multiply)
string ** number
CRASH!!
number ** number
exponent (math)
string ** number
CRASH!!

Random Stuff

import random

intlist = [1,2,3,4,5]
random_int = random.choice(intlist)
print (intlist,random_int)

fplist = [3.5,4.02,5.55,9.65,7.02]
random_fp = random.choice(fplist)
print (fplist,random_fp)

strlist = ['dog','cat','monkey','elephant','squirrel']
random_list = random.choice(strlist)
print (strlist,random_list)

mylist = [1,3.2,'snow']
random_item = random.choice(mylist)
print (mylist,random_item)

myvar1 = 1
myvar2 = 2
myvar3 = 3
varlist = [myvar1,myvar2,myvar3]
random_var = random.choice(varlist)
print (varlist,random_var)

Largest of two numbers

def max2(num1, num2):
    maxvalue = num1

    if num2 > maxvalue:
        maxvalue = num2

    return maxvalue

print(max2(4,5))
print(max2(33,5))

Largest number in the list

def maxlist(list):
    maxvalue = list[0]

    for item in list:
        if item > maxvalue:
            maxvalue = item

    return maxvalue

mylist = [1,2,3,4,55,66,777,0,1]
print(maxlist(mylist))
 

Function

print()
displays inform­­ation on the screen
input()
receives inform­­ation from the user
int()
converts a value to an integer
float()
change number to be decimal number
str()
a list of number, letter and symbols
len()
the length of the string
#
comment, no effect
"­"­"................."""
multiple line comment

Symbols

= =
equal to
!=
no equal to
<
less than
>
more than
<=
less than or equal to
>=
more than or equal to
+
add
-
subtract
*
multiply
/
divide and quotient is float
//
divide and quotient is integer
**
exponent
%
modulo: the remainder

Sort word per line

mystr = "­­He­l­l­o"

letter_num = 0

while letter_num < len(my­­str):
print (mystr­­[l­e­t­te­­r_num])
letter_num = letter_num + 1

Convert to binary

user_number = ' '

while True :
    binary_string = ' '
    user_number = input ("Enter a number to convert to binary")
    number = int (user_number)
    while (number > 0):
        remainder = number%2
        binary_string = str(remainder)+ binary_string
        number = number//2

    print ("Binary string is", binary_string)

Print Name

name = "tim GIRARD­­"

print (name.u­­p­p­er()) → TIM GIRARD
print (name.l­­o­w­er()) → tim girard
print (name.c­­a­p­i­ta­­lize()) → Tim girard
print (name.t­­i­t­le()) → Tim Girard

Area of circle code

def areaOfCircle (r):

    if r <= 0:
        return "Error: invalid radius"
    
    pi = 3.1415
    area = pi r * 2
    return area

user_radius = float(input('Enter the radius:'))

print("The area of the circle is", areaOfCircle(user_radius))

Largest of three values

def max3(num1, num2, num3):
    maxvalue = num1
    if (num1 > num2) and (num1 > num3):
        maxvalue = num1
    elif (num2 > num1) and (num2 > num3):
        maxvalue = num2
    else: maxvalue = num3

    return maxvalue

print (max3(1,2,50))
print (max3(51,2,50))
print (max3(1,255,50))
 

Using Boolean

print(True)
print (2<3)
print (2 != 2)

Number to Hex

user_number = input("please enter a number: ")
number = int(user_number)
hex_string = ' '
while (number > 0):
    remaider = number % 16
    if remaider == 10:
        remaider = 'A'
    elif remaider == 11:
            remaider = 'B'
    elif remaider == 12:
            remaider = 'C'
    elif remaider == 13:
            remaider = 'D'
    elif remaider == 14:
            remaider = 'E'
    elif remaider == 15:
            remaider = 'F'
                            
    hex_string = str(remaider) + str(hex_string)
    number = number // 16
print ("Hexadecimal string is 0x", hex_string)

Area of Circle

"­­"­"
Python Intro Assignment #2
name
student number
"­­"­"

#Ask the user for a radius of a circle
user_r­­adius = input(­­"What is a radius of a circle­­?")

#Convert the given radius to a floating point
radius = float(­­us­e­r­_r­­adius)

#Make a variable called pi
pi = float(­­3.1­415)

#Calculate the area of the circle using exponents
area = pi(ra­­diu­­s*2)

#Display the area of the circle to the user
print ("The area of the circle is", area)

Sort fruit list

fruits = [] #an empty list

for number in range(5):
    user_fruit= input("­Please enter a fruit")
    fruits.append(user_fruit)

print ("Size of fruit list is", len(fruits))

fruits.sort()

for fruit in fruits:
    print ("Fruit: ", fruit)


for fruit in fruits:
print ("Fruit: ", fruit)

Bracket codes

def myprint(text):
    print ("" + str(text) + "")

    return

myprint("1)
myprint("hi")
myprint("2.5")

def myprintnew(text, decoration):
    print(decoration + str(text) + decoration)

    return

myprintnew(1, "+++")
myprintnew('hello','||||||||||||||||')
myprintnew(1, "-------")

Print Definition (Loop)


def printDefinitions(word):
    if word == "variable":
        print ("""

        A variable is the vaule that can changes

        """)

    elif word == "function":

        print ("""

        A function is a block of code that can reuse

        """)

    elif word == "string":
        print ("""

        A String is a list of characters

        """)
    elif word == "parameter":
        print ("""

        A Parameter is something you give to the function

        """)
    elif word == "argument":
        print ("""

        An Argument is thing that give to function

        """)
    elif word == "function call":
        print ("""
        
        A Function call is to tell the function/code to run

        """)
    else:
        print("Unknown word")
while True:
    user_input = input("Enter words: ")
    printDefinitions(user_input)

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