Section 1
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elif statement
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Section 1
(50 cards)
elif statement
This statement can be used when you want one of many possible clauses to run. It consists of the elif keyword, a condition, a colon, and an indented block of code. Ex. if condition: .......... elif name == 'Bob': print('Hi Bob') else: .......... Note: once one of these conditions is found to be True all others are skipped. If the if and elif statements are False only the else statement will run.
try and except
These keywords allow you to handle errors. Ex. try: some code that might work. except error_name_here: error message that you wrote.
round()
This function is used to round floats. Ex. round(3.14) 3 round(1.5) 2
break
This keyword is used to break out of a loop when it is approached by the program.
else statement
This flow control statement only runs when the if statement or elif statements are false. It uses the else keyword, a colon, and then an indented block of code. Ex. else: print('You're not Alice')
Condition
An expression that evaluates down to a Boolean value.
Data Type
A category into which values fall into. This can include strings, integers, or floats. Ex. int: 5, -3, 1 float: 3.14, -1.5, 4.0 string: 'Hello World', '101 Dalmatians' note: Strings must be within either single quotes or double quotes.
Initialization
The first time a variable is created or the first time a value is stored in a variable.
None
A data type in Python consisting only of the keyword None. This represents the absence of a value. It is helpful when you need to store something that won't be confused for a real value in a variable. Note: As with True and False, None must be capitalized.
random.randint()
This function is used to generate random numbers. It can be passed two arguments. Ex. random.randint(0, 10) This code will generate any random number between 0 and 10. Note: You must import the random module to use this function.
abs()
This function returns the absolute value of the number passed to it. Ex. abs(-5) 5 abs(3.14) 3.14
overwriting
When a variable is assigned a new value the old one is forgotten.
return statement
Used to declare what a function returns when it evaluates an expression. To write a return statement you use the return keyword and the value or expression that the function should return. Ex. return 2 + 2
str()
This function is used to convert an integer or a float into a string. Ex. str(29) '29'
Comment
A line that Python ignores. These are used to document your code and make it easier for you and others to understand the code when looked at later. To create a comment: # This is a comment in Python
Operator
A symbol that performs an operation on some values. Ex. +, -, , /, %, *
Expression
The most basic kind of programming instruction. Consists of values and operators that can reduce down. Ex. 2 + 2
input()
Waits for the user to type some text on the keyboard and press enter. This input can be saved to a variable like so: spam = input() Note: The value stored using the input function is a string value.
What are legal variable name?
It can only be one word. It can only use letters, numbers, and the underscore character. It can't begin with a number. Note: variable names are case-sensitive meaning Spam and spam are considered different variables.
Boolean Values
The values True or False are Boolean values. They are keywords and cannot be used as variables. You must capitalize the first letter of either of these keywords. Ex. spam = True
continue
This keyword jumps to the beginning of the loop when it is encountered.
global scope
Every part of the program has access to variables in the global scope. Note: Global variables can be read from local scope.
variable
A place in the computer's memory where you can store a single value. The example below shows how to declare a variable. You can use variables in expressions with other variables. Ex. spam = 42
import
This keyword is used to import a module into your program. A module is a Python program that contains a group of related functions that can be used in your program. An import statement consists of: Ex. import random or from random import * Note: an import statement can include more than one module. Ex. import sys, os, math, random
while loop
A control structure that makes an area of code run multiple times. It will run while a condition is True. It consists of the while keyword, a condition, a colon, and an indented block of code. Ex. spam = 0 while spam < 5: print('Hello') spam = spam + 1 This code prints Hello five times. Note: If you are trapped in an infinite loop in the shell you can press ctrl + c to escape it.
Comparison Operators
These operators compare two values and reduce down to a single Boolean value, either True or False == Equal to: Can work with any data type != Not equal to: Can work with any data type < Less than > Greater than <= Less than or equal to >= Greater than or equal to
int()
This function converts string values or floats into integers. Ex. int('29') 29 int(3.14) 3 Note: The int function can be used to round floats down or up. To round up just add 1 after passing the argument to the int function. Note: If you pass a value to int that cannot be evaluated as an integer Python will give you a ValueErrror. Ex. int('99.99') ValueError: invalid literal for int() with base 10: '99.99'
+
When put between two numerical values it becomes the addition operator. When put between two strings it becomes the concatenation operator. Ex. 2 + 2 4 'Hello ' + 'World' 'Hello World' Note: Python will not understand the expression if you try to add an integer value and a string. Ex. 'Alice' + 42 TypeError: Can't convert 'int' object to str implicitly.
global
This is a keyword in Python that allows you to define a global variable within a functions code block.
float()
This function converts integers into floats. Ex. float(4) 4.0
Code Block
Where a group of code begins and ends. In Python code begins with an indentation and ends when the indentation decreases to zero. Note: blocks can contain other blocks.
=
This is the assignment operator it assigns a value to a variable
Text and Number Equivalence
If an integer and a float are the same number they are considered equal. Ex. 42 == 42.0 True But an integer and a string or a float and a string are not considered equal. Ex. 42 == '42' False 42.0 == '42' False
Argument
A value that is passed to a function.
print()
This function displays the text data within it to the screen. Ex. print('Hello World') Hello World
argument
A value that is passed to a function
local scope
The programs access to variables within a code block. Local scope refers to variables that reside in code blocks. Note: When a scope is destroyed all values within it are forgotten. Note: Local variables cannot be used in the global scope.
for loop
This loop runs code a set amount of times. It consists of the for keyword, a condition, a colon, and an indented block of code. Ex. for
function
A function is like a mini program within a program. It allows programmers to group code. They also prevent you from having to repeat code.
Order of operations/ precedence
A mathematical rule stating that mathematical operations in a formula are calculated in this order (1) exponents and roots, (2) multiplication and division, and (3) addition and subtraction. You can use parentheses to overwrite the normal order of operations.
parameter
A variable that an argument is stored in when a function is called. Note: The value stored in a parameter is forgotten when the function returns.
Boolean Operators
The Boolean operators are and, or, and not. They are used to compare Boolean values and like comparison operators they evaluate down to Boolean values. Ex. True and True True True and False False
len()
Takes a string value and returns the length of the value as an integer.
def
This is the keyword in Python used to define a function. Ex. def some_function(): some code in this block Note: Defining a function does not call it. To call the function you type function_name()
SyntaxError: EOL While scanning string literal
This error happens when you forget to add the closing quote to a string or the closing parentheses to a function when calling it.
range()
This function allows you to give it an integer value that can be used with a for loop to run through a sequence of integer values. Note: range() can be passed multiple values. Ex. range(12, 16) This will start at 12 and will go up to but not include 16. Ex. range(12, 16, 2) This will start at 12 and will go up to but not include 16 in increments of 2.
if statement
This is a flow control statement: begins with the keyword if, next a condition, a colon, and starting on the next line an indented block of code(the clause). Ex. if name == 'Alice': print('Hi, Alice')
*
When put between two numerical values it becomes the multiplication operator. When used between a string and an integer it will replicate that string that number of times. Ex. 'String' * 3 'StringStringString' Note: If Python gets anything other than these two conditions it will give you an error. 'String' * 4.5 TypeError: can't multiply sequence by non-int of type 'float'
sys.exit()
This function can be used to terminate a program. Note: The sys module must be imported to use this function.
Flow Control
Decides which statements in a program should run.
Section 2
(50 cards)
in
This keyword determines if an item is in a list. It will return a Boolean value. Ex. 'hello' in ['greetings', 'salutations', 'hello'] True
not in
This keyword determines if an item is not in a list. It will return a Boolean value. Ex. 'goodbye' not in ['greetings', 'salutations', 'hello'] True
del
This keyword can be used to remove a value from a list. Ex. spam = ['cat', 'bat', 'rat'] del spam[1] ['cat', 'rat']
insert()
This method adds a value to a list. It adds this value to the index you specify. It takes two arguments, the index and the value to be added. Ex. spam.insert(2, 'spider') ['cat', 'rat', 'spider', 'bat']
islower()
Returns a Boolean value True if the string has at least one letter and all the letters are lowercase.
isspace()
Returns True if the string consists only of spaces, tabs, and new-lines and is not blank.
isalnum()
Returns True if the string consists only of letters and numbers and is not blank.
istitle()
Returns True if the string consists only of words that begin with an uppercase letter followed by only lowercase letters.
startswith()
Returns True if the string value it is called on begins with the string passed to it.
center()
Returns a padded version of the string it is called on. It centers the string.
sort()
This method is used to sort items in a list. The items can be sorted alphabetically or numerically. If reverse=True is passed to this method it will return the sorted list reversed. Note: You cannot sort lists with both strings and numbers in them. Note: Pass key=str.lower to make sure the list is in order.
List
A value that contains multiple values in a sequence. A list begins and ends with square brackets. Ex. ['this', 'is', 'a', 'list']. Note: methods and functions that work with strings can generally be used with lists.
rstrip()
Strips the white space in a string off of the right side.
Item
A value inside of a list.
get()
When used with dictionaries this method takes two arguments. The key of the value to be accessed and the value to return if said key doesn't exist in the dictionary.
lstrip()
Strips the white space in a string off of the left side.
values()
This method can be used to access values in a dictionary.
isalpha()
Returns True if the string consists only of letters and is not blank.
lower()
Changes all the letters in a string to be lowercase.
items()
This method can be used to access whole key value pairs in a dictionary.
Index
The integer inside the brackets that follow a list. An index is used to access specific values within a list. Ex. spam[1] 'bat' Note: Python will give you an error if you use an index that is not in the range of the available indexes. Note: Indexes can only be integer values.
Multiline Strings
A string that can span multiple lines in Python. The create a multiline string you put text between ''' text here '''.
split()
This method splits a string into a list of strings at the point you pass as an argument. The default is a space.
append()
This method adds a value to a list. It adds this value to the end of the list. Ex. spam.append('bat') ['cat', 'rat', 'bat']
join()
This method combines a list of string values into a single string value. Ex. ', '.join('cats', 'rats', 'bats') 'cats, rats, bats'
dictionary
A collection of many values. It stores data in key value pairs as opposed to indexes. Ex. cat = {'color': 'gray','disposition': 'loud'} Note: Unlike lists items in dictionaries are unordered
index()
This method allows you the find the index of the list value you pass it. Ex. spam.index('hello') 1
Escape character
These are used so that Python doesn't confuse a ' or " for the ending quote in a string. The \ is the escape character in Python.
Ex. 'That is Alice\'s cat.'
\' Single quote
\" Double quote
\t Tab
Newline (line break)
\\ Backslash
Multiline Comments
A comment that can span multiple lines in Python. To create a multiline comment put your information between """ text here """.
list()
This function converts tuples and strings to lists.
upper()
Changes all the letters in a string to be uppercase.
ljust()
Returns a padded version of the string it is called on. It justifies the string to the left.
Raw String
A string that completely ignores all escape characters and prints any backslash that appears in the string. Ex. print(r'That is Carol\'s cat.') That is Carol\'s cat.
copy
This function is used to copy a list. Note: In order to use this function you must import the copy module.
pprint()
This function can be used to "pretty print" a dictionary. Ex. pprint.pprint(count) Note: You must import the pprint module to use this function.
rjust()
Returns a padded version of the string it is called on. It justifies the string to the right.
tuple()
This function converts lists and strings to tuples.
endswith()
Returns True if the string values it is called on ends with the string passed to it.
method
A method is the same thing as a function except it is called on a value. Ex. spam.index('hello')
Slice
Used to get several specific values in the form of a new list. Ex. spam[1:4] This will get the values at indexes one up to but not including four.
keys()
This method can be used to access keys in a dictionary.
Tuple
Is similar to a list except in that the values it contains are immutable and cannot be changed or appended. Note: Strings are also immutable.
reference
A value that points to some bit of data.
type()
This function displays the data type of the value that is passed to it.
pformat()
This function is used to pretty print a dictionary as a string.
deepcopy
This function is used to copy a list within a list. Note: In order to use this function you must import the copy module.
isupper()
Returns a Boolean value True if the string has at least one letter and all the letters are uppercase.
isdecimal()
Returns True if the string consists only of numeric characters and is not blank.
strip()
Strips the white space in a string off of both sides.
remove()
This method removes the list value that is passed to it. Ex. spam.remove('bat') spam ['cat', 'rat', 'elephant', 'tiger', 'snake', 'spider', 'fly', 'monkey']
Section 3
(32 cards)