Python + Flashcards
(203 cards)
1
Q
Use _________ to determine which operations are performed first
A
Parenthesis
2
Q
Computers can’t store ______ completely accurately, which can lead to bugs.
A
Floats
3
Q
How do you include a character that can’t be directly included in a string? Ex: a double quote
A
Use a backslash
4
Q
How do you prompt the user for input?
A
input(‘prompt’)
5
Q
User input is automatically returned as a ______. (With the contents automatically escaped.)
A
String
6
Q
As with integers and floats, _______ in Python can be added, using a process called __________.
A
strings, concatenation
7
Q
To add a string that contains a number to an integer you must first __________________.
A
Convert the string to an integer
8
Q
You can multiply a string by a float. (T or F)
A
False
9
Q
what is the output of this code:
print(3 * ‘7’)
A
777
10
Q
How do you convert the string “83” into the integer 83?
A
int(“83”)
11
Q
How do you convert the integer 7 into the float 7.0?
A
float(7)
12
Q
What is the output of this code and why? \n\n\nint(‘6’+’3’)
A
63 , because the operation inside the parenthesis is done first and while ‘6’ and ‘3’ are inside the parenthesis they are strings so their sum is ‘63’, which is THEN converted into the integer 63
13
Q
How do you convert user input (which is automatically a string) into an integer?
A
int(input(“prompt:”))
14
Q
Variables can be reassigned as many times as you want. (T or F)
A
True
15
Q
You can assign a variable to an integer and then later assign that same variable to a string. (T or F)
A
True
16
Q
The only characters allowed in a variable name are:
A
Letters, Numbers, Underscores
17
Q
is 13_Hab an acceptable variable name?
A
No, variable names cannot begin with numbers
18
Q
Variable names are _____ sensitive.
A
case
19
Q
How do you delete a variable?
A
del variable name
20
Q
You can also take the value of the variable from user input. (T or F)
A
True
21
Q
In–place operators allow you to write code like \n’x = x + 3’ more concisely, as:
A
x + = 3
22
Q
What is the output of this code?
x = 3
num = 17
print(num % x)
A
2 (remainder)
23
Q
What is the Boolean equal operator in python?
A
==
24
Q
What is this Boolean operator? !=
A
Not equal to
25
Is this a true or false statement?\n\n\n1 != 1
False
26
Is this a true or false statement?\n\n\n2 != t
True
27
What are the Boolean operators for greater than / less than?
>
28
What are these Boolean operators?
| <= >=
Greater than / less than (or equal to)
29
You can use an __ ________ to run code if a certain condition holds
if statement
30
Python uses ______ to delimit blocks of code
Indentation
31
The end of an if statement should contain a _.
:
32
If statements can be _______ to perform more complex checks. This is one way to see if ______________ are met.
nested, multiple conditions
33
What is the output of this code?\nnum = 7\nif num > 3: \n print("3") \n if num < 5: \n print("5") \n if num ==7: \n print("7")
3, because since 7 is not less than 5 the next nested statement is never reached
34
An else statement follows __________.
An if statement
35
An else statement contains code that is called when _____________________.
The if statement evaluates to false
36
(T or F)
| Else statements must be followed by a :
True
37
The _____ statement is a shortcut to chaining if else statements.
elif
38
The and operator takes two arguments and evaluates as true if _________.
both arguments are true
39
The or operator takes two arguments and evaluates to true if ______________.
Either (or both) arguments is/are true.
40
Each character inside of a sting has a number, this number is called the _____
index
41
what is the output of:\n\n\n'python'[2]
t (always begin counting from 0)
42
what does the string function .len() do?
Gives you the number of characters in the string.\n(length)
43
write a line of code that gets rid of all capitalization in the variable named parrot
parrot.lower()
44
What will this line of code do?"parrot".upper()
Make all letters in the string "parrot" uppercase
45
str() turns _______ into ________
non–strings into strings
46
Methods using dot notation (such as "String".upper() ) only work with _________.
Strings
47
T or F) \n \nWhen you want to print a variable inside of a string, the best way is concatenation
False
(name = "Eric" age = 74)
f"Hello, {name}. You are {age}.")
48
use the % operator to replace the__ placeholders with the variables in parentheses.
%s
49
```
According to operator precedence what is the output of this code?
if 1 + 1 * 3 == 6:
print("Yes")
else:
print("No")
```
No
50
What are the 5 basic categories of statements that programming languages have.
```
Conditional
Looping
Function
Assignment
Declaration
```
51
______ = 5.0 / 3.0 * 6.0
10.0
52
When a function is executed, what happens when the end of the function statement block is reached?
Execution returns to the statement that called it.
53
For a function to be used in an expression, it must _____________ .
Return a Value
54
A __________ is the part of a program in which a variable may be accessed.
Scope
55
while in a loop, a _____________ command allows to to exit before the completion of the loop
Break
56
A simple conditional statement taught in this course starts with the key word _____ .
if
57
What are two keywords used to start loop (repeating) statements in Python?
For and While
58
A loop that repeats a specific number of times is know as a(n)_________________.
Count controlled loop
59
What value will be printed after this code in run?
x = 12\ny = 10\ny += 15
myvar = x + y
print myvar
37
60
______________ gives us this ability to choose among outcomes based off what else is happening in the program.
Control flow
61
evaluate
| not 41>40
False
62
evaluate
| not 65 < 50
True
63
evaluate
| not not 50 != 50
False
64
What is the order of operations for boolean operators?
not
and
or
(in?)
65
an __/_____ statement says "If this expression is true, run this indented code block; otherwise, run this code after the else statement."
if/else
66
use _________ to determine if a string is letters.
STRING.isalpha()
67
Create a line of code that checks if user input has more than 0 characters AND is all letters
if len(INPUT) > 0 and INPUT.isalpha()
68
when selecting a section of a string that should include the end, for the second index you can use .len() or you can ______.
Leave second index blank
69
How do you use pi?
from math import pi
70
How do you use the sleep function?
from time import sleep
71
Write some code that will print the current date and time
from datetime import datetime\nnow = datetime.now()\nprint now
72
How do you print a float to the second decimal place using string formatting?
%.2f
73
How do you insert a float using string formatting?
%f
74
What are the 3 general parts of a function?
Header (includes 'def')
Comment (optional)
body (indented)
75
```
what is n?
def square(n):
```
a parameter, which acts as a variable name for a passed in argument.
76
T or F You can call another function from within a function
True
77
```
What does this code do?
def cube(number):
return number**3
def by_three(number):
if number % 3 == 0:
return cube(number)
else: return False
```
when cube is called it will return the cube of the number.\n\n\nwhen by_three is called it will return the number cubed IF the number is divisible by three
78
Write a line of code that prints the square root of 25 using built in functions
import math
| print math.sqrt(25)
79
How do you import just one function from a module?
from module import function
80
What if you want all of the math functions but don't want to keep typing in ' math. ' before calling each function, what can be done?
rom math import *\n(Universal import)
81
Why is it not always a good idea to use a universal import?
if you have functions named the same as the functions in the module it can confuse the program.
82
What will this code return?
| max( 2 , 6 , 9, –10)
9
83
What is the absolute value function?
abs()
84
what does the type() function do?
returns the data type of the argument:\n(str, int, float)
85
(T or F) it is acceptable to call a function with a different variable name than the one used when the function was originally created
True
86
What will this code do?
| from random import randint(1,99)
give you a random integer between 1 and 99
87
%d prints ______ as %s prints strings
Integers
88
A list goes between _______ separated by ______
Brackets , commas
89
sorting a list
sorted() returns a new list
sorted([5, 2, 3, 1, 4])
[1, 2, 3, 4, 5]
90
.sort()
The sort() method sorts the elements of a given list in a specific ascending or descending order. The syntax of the sort() method is: list.sort(key=..., reverse=...)
Modifies existing list
91
How do you assign a new element to a specific index in list?
list_name[desired index] = entry
92
what does the append() function do when used in a list?
Adds the appended element to the end of the list (eg. append(listmember))
93
How do you take just the portion of this list between the second and third positions?
letters = ['a', 'b', 'c', 'd', 'e']
(Remember to begin counting at 0 and that the number after the colon is NOT included)
portion = letters[1:3]
94
what can you use to find the index of a certain element in a list?
list_name.index("element")
95
How would you insert the item "Blue" as the second item in the list named colors?
colors.insert(1,"Blue")
96
if you want to do something with every item in a list you can use a ___ ______.
For loop
97
How do you use a for loop for every item in a list?
for item in list_name:
98
When accessing a value from a dictionary you use a ___ instead of an index
Key
99
(T or F) When accessing a value from a dictionary you use curly brackets.
False, use [] brackets as in a list
100
(T or F)\n\n\nYou can put lists inside of dictionaries
True
101
How is a dictionary formatted?
{ 'Key' : value , 'Key2' : value }
102
How do you add a new key–value pair to a dictionary?
dictionary_name['Key'] = Value
103
How would you delete the key–value pair with the key "Blue" in the dictionary "Colors"
del colors['Blue']
104
How do you remove an item from a list?
list_name.remove('item')
105
(T or F)\nyou can use a for loop on a dictionary.
True
106
(T or F)
| You can access the key and the value of a dictionary with a for loop
True
107
You can use a for loop on a string to perform an action on ____________ in the string.
every character
108
```
What does this code do?
def compute_bill(food):
total = 0
for n in food:
total += prices[n]
return total
```
1. ) defines a function called compute_bill that takes an argument called 'food'
2) sets the variable 'total' to 0
3. ) for every item in the list 'food' it will find that item by key in the dictionary 'prices' and add its value to the other items in the 'food' list
4. ) prints result
109
What will this code print?
my_dict = {"shirts": 5, "pants": 4, "shoes": 2}
print my_dict["pants"]
4
110
What does this .pop() function do?listname.pop(x)
removes the item at index x and returns list
111
(T or F) items in a list must be inside of quotes
False
112
When you divide an integer by an integer the result is always a ______ _________ down
integer rounded
113
what will this code do?
letters = ['a' , 'b' , 'c']
print ' '.join(letters)
will print the letters list with a space in place of the quotation marks and commas
114
what is the function which removes the item at the given index from the list but does not return the list?
del(listname[index])
115
Besides using a for loop, how can you iterate through items in a list?
Using the range function
116
use the range function to perform the same task on a list as the ## for item in list: function
for i in range(len(list)):
117
(T or F) \n\n\nThe range function must be attributed to a certain list name when used in a for loop
False
118
what will this code do?
letters = ['a' , 'b' , 'c']
print ' '.join(letters)
will print the letters list with a space in place of the quotation marks and commas
The join() method provides a flexible way to create strings from iterable objects. It joins each element of an iterable (such as list, string, and tuple) by a string separator (the string on which the join() method is called) and returns the concatenated string.
119
(T or F) The range function must be attributed to a certain list name when used in a for loop
False
120
how do you select an element from a list within a list?
listname[outer_list_index][inner_list_index]
121
What will this code return?
my_list = [8, 6, 4, 2]
my_list.pop(1)
[8, 4, 2]
122
What will this code return?
| my_list = [1, 3, 5, 7] \nmy_list.remove(3) [1, 5, 7]
[1, 5, 7]
123
What will this code return?
my_list = [1, 2, 3, 5]
my_list[2] = my_list[1] + 2
[1, 2, 4, 5]
124
Replace the line in the function so that the functions prints every other list item.
```
def print_list(x):
for counter in ________________: print x[counter]
```
range(0, len(x),2)
125
A while loop executes _____________________.
WHILE a condition holds true
126
What is one method for using a while loop so that it does not become infinite and iterates a certain amount of times?
Use an increment count
127
(T or F) You can use a while / else loop
True
128
When looping over the dictionary do you get the key or the value?
you get the key which you can use to get the value.
129
What built in function allows you to iterate (gentage) over two lists at once?
the zip function
130
(T or F) The zip function can handle 4 lists at once
True
131
(T or F) The zip function will stop at the end of the longer list
False, it will stop at the end of the shorter list
132
Write an opening line of code that uses the zip function on a list called list_a and list_b
For a , b in zip(list_a , list_b):
133
how do you separate a sentence (string) into a list with each word?
string.split()
| The split() method splits a string into a list.
134
```
What will this code do?
word = 'apples'
print len(word)
```
return the length of the word 'apples'
135
What does the zip function do?
It creates pairs of elements when passed two lists
fx
number_list = [1, 2, 3]
str_list = ['one', 'two', 'three']
Output: {(2, 'two'), (3, 'three'), (1, 'one')}
136
What function can be used to supply an index to each element of a list as you iterate through it?
enumerate()
137
Besides datetime what is another function you can use to obtain current time functions?
strftime
138
Write a line of code that will check the amount of keys in a dictionary
len(dictionary.keys())
139
(T or F) when using the .items() function on a dictionary, it will print the items (keys and values) in the order they are in the dictionary
False
140
Write a line of code that will return all the keys for a dictionary in no particular order
dictionary.keys()
141
what is the format for taking only certain elements from a list?
list[start:end:stride]
142
How do you print a list in reverse?
make the stride negative
| [::–1]
143
What is a lambda?
```
an anonymous function
fx:
def myfunc(n):
return lambda a : a * n
```
mydoubler = myfunc(2)
print(mydoubler(11))
Output: 22
144
what is the syntax for using a lambda? filter
(lambda x: CONDITION , list_to_filter)
145
If you want to write a number in binary what must it begin with?
0b
146
how do you convert an integer into binary?
bin()
147
What is XOR?
How do you initialize the object(s) of a class? def __init__(self):
XOR, also known as "exclusive or", compares two binary numbers bitwise. If both bits are the same, XOR outputs 0. If the bits are different, XOR outputs 1.
148
What is a class?
a way of organizing and producing objects with similar attributes and methods.
Almost everything in Python is an object, with its properties and methods.
A Class is like an object constructor, or a "blueprint" for creating objects.
149
How do you initialize the object(s) of a class?
| initialize = to set (something, such as a computer program counter)
def __init__(self):
150
What should you use as the first parameter when instantiating a class?
self
151
You can access an attribute of a class using ___ notation
dot
152
how can you give all objects of a class the same variable without actually initializing it?
inside of the class, before __init__(), create a new variable and set it equal to the desired value
153
What do you call a function inside of a class?
A method
154
(T or F) When creating a method, you do not have to pass in the self argument if you already did so in __init__()
False
155
```
Write a line of code that calls the method 'description' on the object 'hippo' and prints it
what is inheritance? the process by which one class takes on the attributes and methods of another
What does this code do?\n\n\nclass Triangle(Shape): opens a class called 'Triangle' that Inherits the class 'Shape'
```
print hippo.description()
156
what is inheritance?
the process by which one class takes on the attributes and methods of another
157
```
What does this code do?
class Triangle(Shape):
```
opens a class called 'Triangle' that Inherits the class 'Shape'
158
when using dot notation, does the object or the class name come first?
object
159
```
What does this class inherit?
class ClassName(object):
```
the properties of an object, which is the simplest, most basic class
160
What is a variable that is only available to a certain class called?
A member / member variable
161
An instance of a class automatically has access to what variables?
Member variables
162
```
This is the correct way to print the 'condition' of 'my_car'
class Car(object):
____condition = 'new'
my_car = Car()
print my_car.condition
```
True
163
```
This is the correct way to print the 'condition' of 'my_car'
class Car(object):
____condition = 'new'
my_car = Car()
print condition.my_car()
```
False
164
What is the format for calling a method inside of a class?
instance = ClassName(att1, att2, att3)\nprint instance.method()
165
```
What will the following print to the console?
my_list = range(10)
print filter(lambda x: x**2 / 3 < 5, my_list)
```
[0, 1, 2, 3]
166
What is this list comprehension equal to?\n\n\n [i for i in range(10) if i % 3 == 1]
[1, 4, 7]
167
When does python write data to a file?
When you close the file
168
What is file I/O?
File input / output
169
Create a variable, my_file, and set it equal to calling the open() function on output.txt. In this case, pass "r+" as a second argument to the function so the file will allow you to readand write to it!
my_file = open('output.txt', 'r+')
170
What does the use of 'w' do when opening a file?
opens in write–only mode
171
How do you open a file in read only mode?
my_file = open('filename.txt', 'r')
172
How do you open a file in read and write mode?
my_file = open('filename.txt', 'r+')
173
How do you open a file in append mode?
my_file = open('filename.txt', 'a')
174
What MUST you do in order for python to write to the file properly?
Close the file when done writing to it
175
my_file.write() will only take what as an argument?
strings
176
How do you close the file when you are done writing to it?
my_file.close()
177
What do you have to do before reading or writing to a file?
open it (determine how you would like to)
178
write a line of code that prints the result of reading my_file
print my_file.read()
179
How do you read one line of a file at a time?
.readline()
180
What is buffered data?
data that it is held in a temporary location before being written to the file.
181
what does the .closed attribute do?
returns True if the file is closed and False otherwise
182
What function is required for classes to initialize objects?
__init__()
183
How does using a for loop on a file work?
for line in f:
184
T or F) Lists can be added and multiplied
True
185
What will this code output?
list1= [1, 2, 3]
print(list1 + [4, 5, 6])
[1, 2, 3, 4, 5, 6]
186
How does the 'in' operator work?
Checks if an item is in something (like a list or string) and then returns True if it is and False if it is not.
187
```
What is the output?
sweet = "cookies"
savory = "pickles"
num = 100
print (num, savory,"and",num, sweet)
print ("I choose the", sweet.upper())
```
100 pickles and 100 cookies
| I choose the COOKIES
188
Fastest way to make a list of numbers with range:
l1 = list(range(2,41))
| print(l1)
189
Fastest way to make a list with same numbers with for loop:
my_list = [1 for i in range(50)]
| print (my_list)
190
items()
The items() method returns a view object. The view object contains the key-value pairs of the dictionary, as tuples in a list.
191
Abs()
Absolut value
192
Try:
Pass:
Except:
The critical operation which can raise an exception is placed inside the try clause. The code that handles the exceptions is written in the except clause.
We can thus choose what operations to perform once we have caught the exception.
In the above example, we did not mention any specific exception in the except clause.
This is not a good programming practice as it will catch all exceptions and handle every case in the same way. We can specify which exceptions an except clause should catch.
A try clause can have any number of except clauses to handle different exceptions, however, only one will be executed in case an exception occurs.
193
File I/O
open() returns a file object
open(filename, mode)
mode (optional) describes how the file is used:
– 'r' for reading (default)
– 'w' for writing (overwrites existing file)
– 'a' for appending (appends to existing file)
– 'r+' for reading and writing
194
How to reverse a list with a method
The reverse() method reverses the elements of the list.
list.reverse()
195
Reverse a List Using Slicing Operator
```
# Operating System List
systems = ['Windows', 'macOS', 'Linux']
```
```
# Reversing a list
reversed_list = systems[::-1] (eg. [start:stop:step] )
```
```
# updated list
print(reversed_list)
```
196
How to round a float
round(float_num/variable, num_of_decimals)
197
what does pow() do?
The pow() function returns the value of x to the power of y (xy).
x = pow(4, 3)
print(x)
Output = 64
198
How to replace something
replace() - The replace() method returns a copy of the string where the old substring is replaced with the new substring. The original string is unchanged.
```
song = 'cold, cold heart'
# replacing 'cold' with 'hurt'
print(song.replace('cold', 'hurt'))
```
```
song = 'Let it be, let it be, let it be, let it be'
# replacing only two occurences of 'let'
print(song.replace('let', "don't let", 2))
```
Output:
hurt, hurt heart
Let it be, don't let it be, don't let it be, let it be
199
What does the strip() func do?
```
The strip() method returns a copy of the string by removing both the leading and the trailing characters (based on the string argument passed).
If nothing passed it removes whitespaces
remember to leave a whitespace, when using it (eg. string.strip(" a")
```
string = ' xoxo love xoxo '
```
# Leading and trailing whitespaces are removed
print(string.strip())
```
All ,x,o,e characters in the left & right of string are removed:
print(string.strip(' xoe'))
```
# Argument doesn't contain space
# No characters are removed.
print(string.strip('stx'))
```
string = 'android is awesome'
print(string.strip('an'))
```
Output
xoxo love xoxo
lov
xoxo love xoxo
droid is awesome
```
200
Write a line of code that will check the amount of keys in a dictionary
len(dictionary.keys())
201
re.sub
This method replaces all occurrences of the RE pattern in string with repl, substituting all occurrences unless max provided. This method returns modified string.
```
fx:
#Remove anything other than digits
num = re.sub(r'\D', "", phone)
print "Phone Num : ", num
Output:
Phone Num : 2004959559
```
202
what does dict.keys() do?
Python dictionary method keys() returns a list of all the available keys in the dictionary.
203
Files = os.listdir("texts")
dicts = {}
for f in files:
text = open("texts/"+f,"r",encoding='UTF8')
os.listdir() This method returns the list of all files and directories in the specified path. The return type of this method is list
Next a for loop to loop through files in folder
