Basics
The Ultimate Python Cheat Sheet Keywords Keyword Description Code Examples False, True. String Python Strings are sequences of characters. String Creation Methods: 1. Functions to access all keys and values of the dictionary print( cal'apple '. The return type will be in Boolean value (True or False) word = 'Hello World' word.isalnum #check if all char are alphanumeric word.isalpha #check if all char in the string are alphabetic word.isdigit #test if string contains digits word.istitle #test if string contains title words word.isupper #test if string contains upper case word.islower #test if string contains lower case. Here is my cheat sheet I created along my learning journey. If you have any recommendations (addition. Tagged with python, django, flask, beginners. The Ultimate Python Cheat Sheet Keywords Keyword Description Code Examples False, True Boolean data type False (1 2) True (2 1) and, or, not Logical operators → Both are true → Either is true → Flips Boolean True and True # True True or False # True not False # True break Ends loop prematurely while True: break # finite loop. String Functions (cont) S.upper Returns a string that has all lower characters in string S converted into uppercase characters S.swap ‐ case Returns a string that has all lowercase characters in string S converted into uppercase characters and vice versa S.isup ‐ per Returns True if all alphabets in string S are in upperc ‐ ase.
| Print a number | print(123) |
| Print a string | print('test') |
| Adding numbers | print(1+2) |
| Variable assignment | number = 123 |
| Print a variable | print(number) |
| Function call | x = min(1, 2) |
| Comment | # a comment |
Types
| Integer | 42 |
| String | 'a string' |
| List | [1, 2, 3] |
| Tuple | (1, 2, 3) |
| Boolean | True |
Useful functions
| Write to the screen | print('hi') |
| Calculate length | len('test') |
| Minimum of numbers | min(1, 2) |
| Maximum of numbers | max(1, 2) |
| Cast to integer | int('123') |
| Cast to string | str(123) |
| Cast to boolean | bool(1) |
| Range of numbers | range(5, 10) |
Other syntax
| Return a value | return 123 |
| Indexing | 'test'[0] |
| Slicing | 'test'[1:3] |
| Continue to next loop iteration | continue |
| Exit the loop | break |
| List append | numbers = numbers + [4] |
| List append (with method call) | numbers.append(4) |
| List item extraction | value = numbers[0] |
| List item assignment | numbers[0] = 123 |
Terminology
| syntax | the arrangement of letters and symbols in code |
| program | a series of instructions for the computer |
| write text to the screen | |
| string | a sequence of letters surrounded by quotes |
| variable | a storage space for values |
| value | examples: a string, an integer, a boolean |
| assignment | using = to put a value into a variable |
| function | a machine you put values into and values come out |
| call (a function) | to run the code of the function |
| argument | the input to a function call |
| parameter | the input to a function definition |
| return value | the value that is sent out of a function |
| conditional | an instruction that's only run if a condition holds |
| loop | a way to repeatedly run instructions |
| list | a type of value that holds other values |
| tuple | like a list, but cannot be changed |
| indexing | extracting one element at a certain position |
| slicing | extracting some elements in a row |
| dictionary | a mapping from keys to values |
Reminders
- Strings and lists are indexed starting at 0, not 1
- Print and return are not the same concept
- The return keyword is only valid inside functions
- Strings must be surrounded by quotes
- You cannot put spaces in variable or function names
- You cannot add strings and integers without casting
- Consistent indentation matters
- Use a colon when writing conditionals, function definitions, and loops
- Descriptive variable names help you understand your code better
Conditionals
Lists
Defining functions
Loops
Dictionaries
Comparisons
| Equals | |
| Not equals | != |
| Less than | < |
| Less than or equal | <= |
| Greater than | > |
Useful methods
| String to lowercase | 'xx'.lower() |
| String to uppercase | 'xx'.upper() |
| Split string by spaces | 'a b c'.split(' ') |
| Remove whitespace around string | ' a string '.strip() |
| Combine strings into one string | ' '.join(['a', 'b']) |
| String starts with | 'xx'.startswith('x') |
| String ends with | 'xx'.endswith('x') |
| List count | [1, 2].count(2) |
| List remove | [1, 2].remove(2) |
| Dictionary keys | {1: 2}.keys() |
| Dictionary values | {1: 2}.values() |
| Dictionary key/value pairs | {1: 2}.items() |
Other neat bonus stuff
| Zip lists | zip([1, 2], ['one', 'two']) |
| Set | my_set = {1, 2, 3} |
| Set intersection | {1, 2} & {2, 3} |
| Set union | {1, 2} | {2, 3} |
| Index of list element | [1, 2, 3].index(2) |
| Sort a list | numbers.sort() |
| Reverse a list | numbers.reverse() |
| Sum of list | sum([1, 2, 3]) |
| Numbering of list elements | for i, item in enumerate(items): |
| Read a file line by line | for line in open('file.txt'): |
| Read file contents | contents = open('file.txt').read() |
| Random number between 1 and 10 | import random; x = random.randint(1, 10) |
| List comprehensions | [x+1 for x in numbers] |
| Check if any condition holds | any([True, False]) |
| Check if all conditions hold | all([True, False]) |
Missing something?
Let us know here.Python is great for string manipulation. Python’s string manipulation ability was definitely one of the reasons for its popularity initially. Python’s built-in methods lets you do most common string manipulations. Here are the String object methods in Python and how to use them.
1. How to Check a String Ends With a Suffix?
Python Functions Cheat Sheet
Python String object’s method endswith is great to see if a string/text ends with a specific suffix. It returns True, when the string ends with the suffix, False otherwise.
2. How to Check a String Starts With a Prefix?
Python String object also has a method startswith to see a string/text starts with a specific prefix. It returns True, when the string starts with the prefix, False otherwise.
3. How to Find If A Substring Is in a String?
Often you want to check if a string contains a substring. The best way to do that is use ‘in’ statement in Python.
4. How To Split a String in Python
Often you want to split a text or string using a delimiter and create a list of words in the string. Python’s split() method lets you split a string. By default, split uses consecutive whitespace in the string as a single separator and gets you a list.
You can also specify a delimiter to split method. Here, we split the string with the letter ‘a’ as delimiter.
5. How To Join a List of Strings into a String in Python?
Often one wants to join or concatenate list of strings into a single string. Python’s join() method can be used join strings. While joining we can also specify how we want to join with a delimiter.
6. How To Remove Whitespaces in a String in Python?
Python has three related methods, strip(), lstrip(),rstrip() to remove whitespaces in strings. Let us see examples of using strip(), lstrip(), rstrip() here.
Let us create a text with white spaces in the beginning and in the end.
strip() method removes both the whitespaces, the ones in the beginning and in the end
lstrip() method removes only the left whitespaces and thus leaves the one at the end of the string.
rstrip() method removes only the right whitespaces and thus leaves the one at the beginning of the string.
7. How To Convert to Lower Case?
Python Cheat Sheet Pdf
Python String objects’ lower() method is to convert a string into lower case letters.
8. How To Convert to Upper Case?
Python String objects’ upper() method is for converting a string into upper case. Note all letters in the string will be capitalized.
9. How To Convert to Title Case?
Python’s title() method converts a string to a titlecased version, where the first letter of each word is capitalized, while the characters are lowercase.
Python String Manipulation Cheat Sheet Example
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