Python String and Math Functions Cheatsheet

Posted on Sep 5, 2024 in Computers

len(str) — returns the length of ‘str’
str.format(c) — formats. Use {:.2f} to round to 2 decimals. Always 2, even if the last digit is 0. Uses c as quantity. {:d} for integer types.
str.upper(), str.lower() — makes uppercase, makes lowercase
str.capitalize() — makes the first letter of a sentence uppercase
str.replace(“a”, “b”) — substitutes each case of “a” with “b”
str[0] — returns the first character of the string
str.title() — makes all first letters of words uppercase
str.count(“a”) — returns the count of “a” in str
str.find(‘object’, n) — will return the lowest position of ‘object’ in a string starting at n position (if object is not found, it will return -1)
input(“Text”) — Reads user input as a string argument (Use int(input(“Text”)) or float(input(“Text”)) if you want to input a number)
int(x), str(x), float(x) — converts x to an int, str, or float, respectively.
Alphabetical order: numbers < uppercase < lowercase

math.ceil(x), math.floor(x) — rounds up or down to the nearest value, respectively
math.trunc(x) — deletes the decimals (math.trunc(123.923495) = 123)
math.pi = 3.14159…
math.pow(x, y) — returns x raised to the power y (as a float)
pow(x, y) does the same thing but returns as an integer
math.sqrt(x) — gives the square root of a number x, returns float
abs(x) — gives the absolute value of x
min(a, b), max(a, b) — returns the min/max of the two parameters (you can use more than two parameters)
x % y — remainder of x / y (2 % 4 = 2, 4 % 3 = 1, -4 % 3 = 2)
If the numerator is less than the denominator, it returns the value of the numerator — however, not the case with negative numbers)
x // y — integer division with no remainder (5 // 4 = 1, -5 // 4 = -2), has the same effect as math.floor()
x / y — float division (or simply regular division)
c = a>b, if a is greater than b, sets c to True, otherwise sets c to False
round(float, n) — rounds float to n decimals, drops trailing 0’s.

if (condition):
     Block 1
elif (condition):
     Block 2
else:
     Block 3

def function(parameter(s)):
        function processes
        return (whatever variable you’re manipulating)
    print function(argument(s))
def funct(a):
print(a)
x=funct(6) # doesn’t set x equal to anything, but will print 6
def funct2(b):
return(b)
x=funct2(6) # will set x equal to 6 because it’s returning the value
def funct3(c):
print(c)
print(funct3(6))

Output:

None

int(input()) if inputting a number
Import math – can also do import math as m to shorten your code a bit
You can also say from math import x where x is the function you need, that way you don’t have to write math.x(), you can just write x()
count spaces when counting in len()
\n and \t count for 1 char each
:(colon) after def function(x) and if (condition), indent appropriately
You can’t add integers to strings, but you can multiply integers and strings. For example, if you code “x = 100” and “y=’10 times 10 equals ‘”, there will be an error if you try to do “print(y + x)”. To print such, you must either cast x as a string or use a comma instead of a plus sign. (“print(y + str(x))” or “print(y,x,sep=”)”) However, if you do “print(y * x)”, the program will print “10 times 10 equals ” 100 times.
Ex: s = ”’sdfsf \t ” ”’ -> not a syntax error three quote variable is okay
Can use str(float or int variable) to concatenate rather than using a separator in a print function or string variable
print(“What’s up dawg”, variable, sep=” “, end=”\n”) sep defaults to one space end defaults to “\n”) be equal to what was in the return.
BE CAREFUL using // and % with negative values! You get different outputs (-7//3 means math.floor(-7//3) so the result is -3)
global variables can be used in all functions, whereas local variables are function-specific

Parameter–expected input of function
Argument–actual input of a function
Local variable–any variable inside a function
Syntax error–error which causes the program to not run
Semantic error–error which allows the program to run, but against the intention of the programmer