Python
In the case of opening a file for input (read), is X
'r'
The mode string is X for input files
'r'
for output files
'w'
Any character (except newline character) [MetaCharacters]
.
Slice [Syntax]
:
not True
False
[T/F] 42 == 42.0
True
X means the string must begin with spam.
^spam
A variable name can use only letters, numbers and the __ charecter
_
All classes have a function called X, which is always executed when the class is being initiated.
__init__()
The X function is called automatically every time the class is being used to create a new object
__init__()
If you use data members with names using the double underscore prefix such as X, Python makes it a private variable, which is only directly accessible inside a class.
__privateAttr
The X keyword arguments take a list of regular expression strings to determine what the PyInputPlus function will accept as valid input
allowRegexes
A value being passed to a function in a function call is an .
argument
When you call the print() or len() function, you pass them values, called X, by typing them between the parentheses.
arguments
You'll store values in variables with an __________
assignment statement
An Object contains both X and Y
attributes, behavior
Changes the current working directory to path.
chdir(path)
items are separated with
commas
To define a function is to create it, just like an assignment statement. The X statement defines the sayHello() function
def
The X statement will delete values at an index in a list.
del
A X approach works by recursively breaking down a problem into two or more sub-problems of the same or related type
divide-and-conquer
Inputs a line of text and returns it as a string,including the newline. Returns '' if the end of file is reached.
f.readline()
Outputs aString to a file.
f.write(aString)
If there are groups in the regular expression, then X will return a list of tuples.
findall()
Returns the path of the current working directory.
getcwd()
Ensures the user enters one of the provided choices
inputChoice()
A Regex object's X method searches the string it is passed for any matches to the regex.
search()
Pass the string you want to search into the Regex object's X method. This returns a Match object.
search()
Returns a Match object if there is a match anywhere in the string.
search()
The x method will return None if the regex pattern is not found in the string.
search()
While X will return a Match object of the first matched text in the searched string,
search()
A slice goes up to, but will not include, the value at the X
second index
A common use of X is to split a multiline string along the newline characters.
split()
Python also comes with a set of modules called the
standard library
X methods return True if the string value they are called on begins with the string passed to the method
startswith()
The X is a difference between each number in the sequence.
step
This specifies the string to be searched.
str
The multiple assignment trick is also called
tuple unpacking
Method returns strings uppercase
upper()
Python will give you an IndexError error message if you use an index that exceeds the number of X in your list value.
values
A ______ is like a box in the computer's memory where you can store a single value
variable
Fields are
variables
The X matches 0 to m of the preceding group.
{,m}
To add new values to a list, use X or X methods
Append() . Insert()
A process of using details from a new class without modifying existing class.
Inheritance
Returns a match if the specified characters are at the beginning of the string
\A
Returns a match where the specified characters are present, but NOT at the beginning (or at the end) of a word
\B
Any character that is not a numeric digit from 0 to 9.
\D
Any character that is not a space, tab, or newline.
\S
Returns a match where the string DOES NOT contain a white space character
\S
Backslash [Escape Character]
\\
Returns a match where the specified characters are at the beginning or at the end of a word
\b
Any numeric digit from 0 to 9.
\d
a X in a regex stands for a digit character —that is, any single numeral from 0 to 9.
\d
Newline (line break) [Escape Character]
\n
Any letter, numeric digit, or the underscore character. (Think of this as matching "word" characters.)
\w
str(29)
'29'
What is the result ?
3
>>> a = ','.join(['a', 'b', 'c']) What is the result of len(a)?
5
X store the line number of the original function call so that Python can remember where to return.
Frame objects
X is a way of creating new class for using details of existing class without modifying it.
Inheritance
As Few As Possible (shortest match)
Lazy
['cat', 'bat', 'rat', 'elephant']
List Value
Object Oriented Programming Acronym
OOP
OOP Means
Object Oriented Programming
Variables that contain arguments.
Parameters
Writes the instruction "x=36" and gives it to the Python; Python can understand the intend of the programmer, and then instruct the OS find a block of space in its managed memory space, create an Integer 36
Step One of the Three Step Rule
What does the ___init___() function do in Python
The function is called when a new object is instantiated
There are ____ rules for blocks
Three
and, or and not
Three Boolean Operators
X mode will overwrite the existing file and start from scratch, just like when you overwrite a variable's value with a new value.
Write
Returns a match for any two-digit numbers from 00 and 59
[0-5][0-9]
Continue Lines with
\
The X matches at least n and at most m of the preceding group.
{n,m}
The X matches n or more of the preceding group.
{n,}
The X matches exactly n of the preceding group.
{n}
Exactly the specified number of occurrences [MetaCharacters]
{}
Either or [MetaCharacters]
|
X code checks that values entered by the user, such as text from the input() function, are formatted correctly.
Input validation
Think of a X as a container for variables
Scope
The Python attaches the label x to the memory storage block.
Step Three of the Three Step Rule
The programmer prepares a label (i.e., a variable) x in order to refer to the value 36 later.
Step Two of the Three Step Rule
There are two types of fields - X and Y
class variables, object variables
After reading or writing a file, call the X method before opening the file again.
close()
Python ignores __________
comments
________ is just a more specific name in the context of flow control statements.
condition
When the program execution reaches a X statement, the program execution immediately jumps back to the start of the loop and reevaluates the loop's condition.
continue
AN statement that always follows an if or another X statement.
elif
All methods (i.e., behaviors) in a class have only one specific difference from ordinary functions - they must have an X that has to be added to the beginning of the parameter list, but you do not give a value for this parameter when you call the method
extra first name
Closes an output file. Not needed for input files.
f.close()
Inputs the contents of a file and returns them as a single string. Returns '' if the end of file is reached.
f.read()
Perform a global search over a whole string. Returns a list containing all matches, or an empty list if no matches are found.
findall()
In a slice, the X is the index where the slice starts.
first integer
Indexes can be only integer values, not X.
floats
The while loop keeps looping while its condition is True (which is the reason for its name), but what if you want to execute a block of code only a certain number of times?
for Loop
When your program calls a function, Python creates a X on the top of the call stack.
frame object
Returns True if path names a file and False otherwise
getsize(path)
Returns the size of the object names by path in bytes
getsize(path)
If you need to modify a global variable from within a function, use the X
global statement
But if the variable is not used in an assignment statement, it is an X.
global variable
If there is a global statement for that variable in a function, it is an X.
global variable
The dot-star uses X mode
greedy
Returns True if the string consists only of words that begin with an uppercase letter followed by only lowercase letters
istitle()
The X method is useful when you have a list of strings that need to be joined together into a single string value
join()
What's the data type of mo in the following? import re phoneNumRegex = re.compile(r'\d\d\d-\d\d\d-\d\d\d\d') mo = phoneNumRegex.findall('Cell: 415-555-9999 Work: 212-555-0000')
list
The dot-star will match everything except a X.
newline
A class variable refers to an
object
An X represents an entity in the real world with its attributes and behaviors
object
Variables that have arguments assigned to them are
parameters
When a function is called with arguments, the arguments are stored in the X.
parameters
The X function will return a randomly selected item from the list.
random.choice()
All the regex functions in Python are in the X module
re
Removes the file named path from the current working directory
remove(path)
The concept of OOP in Python focuses on creating X code.
reusable
If you need to quickly reverse the order of the items in a list, you can call the X list method.
reverse()
The X is the index where the slice ends.
second integer
This particular parameter X serves as a placeholder and refers to the actual object itself constructed from this class
self
Just as an index can get a single value from a list, a X can get several values from a list, in the form of a new list.
slice
Lists of number values or lists of strings can be sorted with the X method.
sort()
spam = spam % 1
spam %= 1
spam = spam * 1
spam *= 1
spam = spam / 1
spam *= 1
spam = spam + 1
spam += 1
spam = spam - 1
spam -= 1
The _____ function can be passed an integer value and will evaluate to a string value version of the integer.
str()
The X string method will return a new string without any whitespace characters at the beginning or end.
strip()
'Alice' * 5
'AliceAliceAliceAliceAlice'
The X operator puts the value on the right into the variable on the left.
=
Equal to
==
The X operator asks whether two values are the same as each other.
==
Greater than
>
Greater than or equal to
>=
The X matches zero or one of the preceding group.
?
'Alice' * 5.0
Error
The activity of obtaining relevant information from a collection of (commonly massive) information resources
Information retrieval
Valid or Invalid Variable name? _42
Valid
Valid or Invalid Variable name? account4
Valid
Valid or Invalid Variable name? currentBalance
Valid
Valid or Invalid Variable name? current_balance
Valid
One or more occurrences [MetaCharacters]
+
False and False
False
Valid or Invalid Variable name? 42
Invalid
An escape character consists of a X
backslash (\)
However, a string is X it cannot be changed
immutable
Tuples, like strings, are
immutable
To import a module you need the keyword
import
Technically, a for loop repeats the code block once for each item in a X
list value
Mutliline Comment [Syntax]
""" """"
A class is a X for creating objects
"blueprint"
Ends with [MetaCharacters]
$
Are tuples typed with () or []
()
Multiplication
*
The X matches zero or more of the preceding group.
*
Zero or more occurrences [MetaCharacters]
*
Exponent [Syntax]
**
The X matches one or more of the preceding group.
+
Subtraction
-
The X character in a regular expression is called a wildcard and will match any character except for a newline.
.
You can use the dot-star X to stand in for that "anything." Remember that the dot character means "any single character except the newline," and the star character means "zero or more of the preceding character."
.*
Division
/
int division / floored quotient
//
The first value in the list is at index
0
X mode, on the other hand, will append text to the end of the existing file.
Append
End when the indentation decreases to zero or to a containing block's indentation.
Blocks
X begin when the indentation increases
Blocks
The ____________ data type has only two values: True and False.
Boolean
The X is how Python remembers where to return the execution after each function call
Call Stack
The newly formed class is an X
Child Class
What statements define functions?
Def
DRY means
Don't repeat yourself
Hiding the private details of a class from other objects
Encapsulation
'Alice' + 42
Error
Errors can be handled with try and X statements.
Except
False or False
False
Regular expressions allow a user to specify a pattern of text to search for. Regular expressions can be used only in Python. [T/F]
False
T/F?
False
[T/F] 42 == '42'
False
There is only one X, and it is created when your program begins
Global Scope
Variables that are assigned outside all functions are to exist in the
Global scope
As Many As Possible (longest match)
Greedy
import re haRegex = re.compile(r'(Ha){1,3}') mo1=haRegex.search('HaHaHa')print(mo1.group())
HaHaHa
Regex Module syntax
Import re
Valid or Invalid Variable name? TOTAL_$UM
Invalid
Valid or Invalid Variable name? current-balance
Invalid
AX is created whenever a function is called
Local Scope
Parameters and variables that are assigned in a called function are said to exist in that function's
Local Scope
X Cannot Be Used in the Global Scope
Local Variables
A while is what type of statement?
Loop
Functions are
Methods
While indexes start at 0 and go up, you can also use X for the index
Negative Indexes
Escape character \n is printed as:
Newline
Can a variable name begin with a number?
No
In Python, there is a value called X, which represents the absence of a value.
None
The X value is the only value of the NoneType data type.
None
All of the values in the list after the deleted value will be moved up X
One Index
Parentheses, Exponents, Multiplication, Division, Addition, Subtraction
PEMDAS
Similarly, the existing class is a X
Parent Class
X is a Python module used for serializing and de-serializing Python object structures, also called marshalling or flattening
Pickle
A concept of using common operation in different ways for different data input.
Polymorphism
If the user ever enters invalid input, such as a badly formatted date or a number that is outside of an intended range, X will prompt them for input just like our code in the previous section did.
PyInputPlus
X contains functions similar to input() for several kinds of data: numbers, dates, email addresses, and more.
PyInputPlus
X is not a part of the Python Standard Library, so you must install it separately using Pip.
PyInputPlus
Passing a string value representing your regular expression to re.compile() returns an X
Regex pattern object
X go one step further: they allow you to specify a pattern of text to search for
Regular expressions
X refers to the process of converting an object in memory to a byte stream that can be stored on disk or sent over a network.
Serialization
A raw string completely ignores all escape characters and prints any backslash that appears in the string. [T/F]
True
False or True
True
In OOP, a class creates a new type where objects are instances of the class? [T/F]
True
Strings use indexes the same way as lists do.
True
The code in a while clause will be executed as long as the while statement's condition is X.
True
True and True
True
True or False
True
True or True
True
[T/F] 42.0 == 0042.000
True
not False
True
Valid or Invalid Variable name? TOTAL_SUM
Valid
Local Scopes Cannot Use X in Other Local Scopes
Variables
X means the string must end with spam.
X
What is an accurate declaration x=Circle()? Circle is a class
X contains a reference to a circle Object
What's the output of the following? import re msg = 'My lucky number is 777.'msg Regex = re.compile(r'\d') result = msgRegex.findall(msg[10:100])print(result)
['7', '7', '7']
Returns a match for any digit between 0 and 9
[0-9]
Returns a match where any of the specified digits (0, 1, 2, or 3) are present
[0123]
A set of characters [MetaCharacters]
[]
X matches any character that isn't between the brackets.
[^abc]
Returns a match for any character EXCEPT a, r, and n
[^arn]
Returns a match for any lower case character, alphabetically between a and n
[a-n]
Returns a match for any character alphabetically between a and z, lower case OR upper case
[a-zA-Z]
X matches any character between the brackets
[abc]
Returns a match where one of the specified characters (a, r, or n) are present
[arn]
Signals a special sequence (can also be used to escape special characters) [MetaCharacters]
\
Double quote [Escape Character]
\"
Single Quote [Escape Character]
\'
Returns a match where the string DOES NOT contain digits
\D
Any character that is not a letter, numeric digit, or the underscore character.
\W
Returns a match where the string DOES NOT contain any word characters
\W
Returns a match if the specified characters are at the end of the string
\Z
Returns a match where the string contains digits (numbers from 0-9)
\d
Any space, tab, or newline character. (Think of this as matching "space" characters.)
\s
Returns a match where the string contains a white space character
\s
Tab [Escape Character]
\t
Returns a match where the string contains any word characters (characters from a to Z, digits from 0-9, and the underscore _ character)
\w
Starts with [MetaCharacters]
^
You can also use the caret symbol X at the start of a regex to indicate that a match must occur at the beginning of the searched text.
^
This is the starting index, by default its 0.
beg
The X keyword arguments take a list of regular expression strings to determine what the PyInputPlus function will reject as valid input
blockRegexes
Blocks can contain other
blocks
If another function call is made, Python puts another frame object on the X above the other one.
call stack
A X is a mutable collection of many values.
dictionary
Strings can begin and end with X, just as they do with single quotes
double quotes
This is the ending index, by default its equal to the length of the string.
end
X methods return True if the string value they are called onor ends (respectively) with the string passed to the method
endswith()
Returns True if path exists and False otherwise.
exists(path)
X will not return a Match object but a list of strings—as long as there are no groups in the regular expression.
findall()
theX method will return the strings of every match in the searched string
findall()
Python's regular expressions are X by default, which means that in ambiguous situations they will match the longest string possible
greedy
Call the Match object's X method to return a string of the actual matched text.
group()
PyInputPlus [Syntax]
import pyinputplus
Import the regex module with X.
import re
You can determine whether a value is or isn't in a list with the X operators.
in and not in
The x and x operators can be used with strings just like with list values.
in, not in
However, you can also use an index of a list to change the value at that index.
index
The integer inside the square brackets that follows the list is called an
index
List values have an X method that can be passed a value, and if that value exists in the list, the index of the value is returned. If the value isn't in the list, then Python produces a ValueError error
index()
A variable is _________ the first time a value is stored in it
initialized
The _______ function waits for the user to type some text on the keyboard and press ENTER.
input()
Is similar to inputYesNo(), but takes a "True" or "False" response and returns a Boolean value
inputBool()
Ensures the user enters a date and time
inputDatetime()
Ensures the user enters a valid email address
inputEmail()
Ensures the user enters a valid file path and filename, and can optionally check that a file with that name exists
inputFilepath()
Is similar to inputChoice(), but provides a menu with numbered or lettered options
inputMenu()
Ensures the user enters a number and returns an int or float, depending on if the number has a decimal point in it
inputNum()
Is like the built-in input(), but displays * characters as the user types so that passwords, or other sensitive information, aren't displayed on the screen
inputPassword()
Is like the built-in input() function but has the general PyInputPlus features. You can also pass a custom validation function to it
inputStr()
Ensures the user enters a "yes" or "no" response
inputYesNo()
What is the data type of variable a? a = (1)
int
The _____ function is also helpful if you have a number as a string value that you want to use in some mathematics.
int()
Returns True if the string consists only of letters and numbers and is not blank
isalnum()
Returns True if the string consists only of letters and isn't blank
isalpha()
Returns True if the string consists only of numeric characters and is not blank
isdecimal()
Returns True if path names a directory and False otherwise.
isdir(path)
The X method will return a Boolean True value if the string has at least one letter and all the letters are lowercase
islower()
Returns True if the string consists only of spaces, tabs, and newlines and is not blank
isspace()
The x method will return a Boolean True value if the string has at least one letter and all the letters are uppercase
isupper()
Values inside the list are also called
items
The X method is called on a string, gets passed a list of strings, and returns a string
join()
Indexes for dictionaries are called X
keys
The integer value -1 refers to the X in a list
last index
The function evaluates to the integer value of the number of characters in that string.
len()
The X will return the number of values that are in a list value passed to it, just like it can count the number of characters in a string value
len() function
A X is a value that contains multiple values in an ordered sequence
list
What is the data type of the variable a? >>> a = 'MyABCnameABCisABCSimon'.split('ABC')
list
Lists can also contain other X
list values
Returns a list of the names in directory named path.
listdir(path)
If the variable is used in an assignment statement in the function, it is an X
local variable
Method returns strings lowercase
lower()
The X and Xmethods will remove whitespace characters from the left and right ends
lstrip(), rstrip()
Returns a Match object if there is a match found at the beginning of a string.
match()
What does the function re.search do?
matches a pattern at any position in a string
Objects can also contain
methods
Creates a new directory named path and places it in the current working directory.
mkdir(path)
The __________ is a shortcut that lets you assign multiple variables with the values in a list in one line of code.
multiple assignment trick
A X data type it can have values added, removed, or changed
mutable
A list value is a X data type:
mutable
A good variable _______ describes the data it contains.
name
he definition of the hello() function in this program has a parameter called
name
The X (also called lazy) version of the braces, which matches the shortest string possible, has the closing brace followed by a question mark.
non-greedy
Methods in objects are functions that belong to the X
object
There is only X of the class variable and when any one object makes a change to a class variable, that change will be seen by all the other instances.
one copy
The multiple assignment trick is a shortcut that lets you assign multiple variables with the values in a list in X
one line of code
A variable name can be only _____ ______with no spaces
one word
The X function can open files in write or append mode to create new text files or add to existing text files, respectively.
open()
The X function can open these files to read in their contents as one large string
open()
Keyword arguments are often used for X
optional parameters
Just as with functions, we need to use X to indicate that this class is empty.
pass
if the x is not accessible from the current working directory, Python raises an error.
pathname
A Python command that can print: I'm a student
print("I'm a student")
Print Function [Syntax]
print()
The X is a built-in function of Python which returns a range object, which is nothing but a sequence of integers. i.e.,
range()
A X completely ignores all escape characters and prints any backslash that appears in the string
raw string
Which module in Python supports regular expressions?
re
Which of the following creates a pattern object? (str is a valid regular expression)
re.compile(str)
The simplest way is to use the file method X to input the entire contents of the file as a single string.
read()
Regular expressions, called X for short, are descriptions for a pattern of text.
regexes
Character classes are nice for shortening X.
regular expressions
The X method is passed the value to be removed from the list it is called on.
remove()
Renames the file or directory named old to new.
rename(old, new)
Lists can be replicated just like strings.
replicated
Removes the directory named path from the current working directory
rmdir(path)
Class variables are X
shared
The code that could potentially have an error is put in a X clause. The program execution moves to the start of a following except clause if an error happens.
try
Function that shows the data type
type()
Unlike lists, items in dictionaries are X.
unordered
If a X is being used in the global scope (that is, outside of all functions), then it is always a global variable
variable
The call stack isn't stored in a X in your program
variable
import re sentence = 'we are humans' matched = re.search(r'(.*) (.*?) (.*)', sentence) print(matched.group())
we are humans
You can make a block of code execute over and over again using a
while statement
The X character is called a pipe. You can use it anywhere you want to match one of many expressions
|
Not equal to
!=
SyntaxError: EOL while scanning string literal
" "
Comment [Syntax]
#
Modulus/Remainder [Syntax]
%
'Alice' + 'Bob'
'AliceBob'
Addition
+
Less than
<
Less than or equal to
<=
'Alice' * 'Bob'
Error
False and True
False
True and False
False
Valid or Invalid Variable name? 'hello'
Invalid
Valid or Invalid Variable name? 4account
Invalid
Valid or Invalid Variable name? current balance
Invalid
Valid or Invalid Variable name? hello
Valid
Lines of Python code can be grouped together in ________.
blocks
There is a shortcut to getting the program execution to break out of a while loop's clause early.
brake Statement
If the execution reaches a X statement, it immediately exits the while loop's clause
break
Lists can be X just like strings.
concatenated
An if clause can optionally be followed by an _____ statement.
else
An __ statement's clause will execute if the statement's condition is True. The clause is skipped if the condition is False.
if
The most common type of flow control statement is the __ statement.
if
Python X generates the integer numbers between the given start integer to the stop integer, which is generally used to iterate over with for loop.
range()
At the end of an if clause, the program execution continues after the if statement. But at the end of a while clause, the program execution jumps back to the X of the while statement.
start
The X is the amount that the variable is increased by after each iteration.
step
The range() function can also be called with three arguments. The first two arguments will be the start and stop values, and the third will be the X.
step argument