Introduction to Python

Question 1

Name = {key: value, key: value}

Answer 1

Dictionary

Question 2

dictionary[key] = value

Answer 2

How to add an item to a dictionary or overwrite an existing value

Question 3

dictionary.update({key:value, key:value })

Answer 3

Add multiple items to a dictionary at once

Question 4

Py: How to overwrite an existing value associated to a key in a dictionary

Answer 4

Using the single add method to a key with the same name will overwrite it.
dictionary[key] = value

Question 5

dictionary = {key: value for key, value in zip(varkey, varvalue)}

Answer 5

Create a dictionary using comprehension

Question 6

zip(iterator1a, iterator2a, …)

Answer 6

Takes multiple iterators (list) inputs and returns as a single list of tuples

Question 7

my_dict.get(key)

Answer 7

How to safely retrieve a key from a dictionary (won’t return an error if not there)
Can add an optional default return value if not in the dictionary by (key, value)

Question 8

my_dict.pop(key, default return)

Answer 8

Safely checked for key and removes from dictionary if true. Default return is optional

Question 9

list(my_dict)

Answer 9

Returns a list of all dictionary keys

Question 10

my_dict.keys()

Answer 10

Can be used (And by iteration) to return a viewable (list) key objects

Question 11

my _dict.values()

Answer 11

Return a list of values much like dict_keys

Question 12

my_dict.items()

Answer 12

.keys() and .values() combined returning elements of tuples

Question 13

with open(‘your doc.txt’) as a_doc:
some_contents = a_doc.read()
print(some_contents)

Answer 13

Print contents of a text file

Question 14

with open(‘your doc.txt’) as a_doc:
for line in a_doc.readlines ():
print(line)

Answer 14

Print a single line from a text doc

Question 15

with open(‘your doc.txt’) as a_doc:
first_line = a_doc.readline ()
second _line = a_doc.readline()
print(second_line)

Answer 15

Extract just a single line from

Question 16

open(‘a_file.txt’, ‘w’) as some_file:
some_file.write(‘some text’)

Answer 16

Open a file in write mode - default is r for read
‘a’ to append

Question 17

json.load(file_variable)

Answer 17

Read a json file variable after ‘with open() as’

Question 18

json.dump(input_dict, file_var)

Answer 18

Write to a json file from a dictionary and into an “with open(‘file_var’, ‘w’)” called

Question 19

(a,b,)
if type my_tuple == tuple:
c, d = tuple

Answer 19

Checks if a tuple then assigns to independent variables. You have to do entire contents of tuple at same time

Question 20

.py: return a,b

Answer 20

returns as a tuple
Implied by the comma, can use () if you wish

Question 21

.strip()
.lstrip()
.rstrip()

Answer 21

Remove white space from a variable (str)

Question 22

.removeprefix(‘https://‘)

Answer 22

Remove a prefix from a string - in this case part of the URL but could be ‘Mr/£/$ etc’

Question 23

.removesuffix(‘.py’)

Answer 23

Ideal for removing file types or similar. In this case .py

Question 24

py: add something to the end of a list

Answer 24

.append(something)

Question 25

py: remove something from a list

Answer 25

.remove(something)

Question 26

py: combine lists (use to add multiple items)

Answer 26

new_list = list1 + list2

Question 27

py: add a single item to a list other than .append

Answer 27

my_list + [item]

Question 28

pi: my_list.remove(item)

Answer 28

Remove specified item from a list. If used on a list with duplicates it’ll will remove the first instance.

Question 29

.sort()

Answer 29

permanent sorting of a list
Reverse it by .sort(reverse=True)

Question 30

.sorted()

Answer 30

Presentational (temp) sorting of a list

Question 31

.reverse()

Answer 31

Reverse the order permanently
But you can always repeat to back

Question 32

py: for value in range (1, 5):
print(value)

Answer 32

Returns 1-4 due to zero indexing
could’ve also just given it range(5) for the same result
A 3rd unit would provide a range increment

Question 33

py: variable = list(input)

Answer 33

Convert the input into a list

Question 34

py: min(list)
max(list)
sum(list)

Answer 34

Quick mathematics on list inputs

Question 35

py:
list1 = list2[:]

Answer 35

How to copy a list (as opposed to just sharing it)