Python Composite data types

Question 1

myStr = “Hello World”

print(myStr[2:-4:2])

Answer 1

‘loW’

H is index 0
index -4 is o but is not included
step size is 2

no comma!

Question 2

str1 = “ABC”
str2 = “a b”
newStr = str1 * len(str2)
print(newStr)

Answer 2

ABCABCABC

Space and Tabs are also entities within the string, hence it is counted as len

Question 3

str1 = "ababc"
str2 = "ab"
if str2 * len(str2) in str1:
     print("case1")
elif str2 in str1:
     print("case2")
else:
     print("case3")

Answer 3

Result = case1

str2len(str2) = ab2
ab*2 is in ababc

thus case1

Question 4

membership operation, whats the operator used

Answer 4

in

Question 5

Are string immutable?

Answer 5

yes

Question 6

aStr = 'spam'
newStr = aStr[:1] + 'l' + aStr[2:]

Answer 6

result = slam

Question 7

str1 = “couple”
str2 = “tea”
newStr = str2[:1] + str1[2:]
print(newStr, str1)

Answer 7

tuple couple

Question 8

what does string.find do

Answer 8

find the character within the string and returns its index value.
if the character does not exist, return -1

Question 9

str1 = “couple”
newStr = str1[str1.find(‘ou’):str1.find(‘l’)]
print(newStr)

Answer 9

result= oup

Question 10

str1 = “couple“
str2 = “t”
newStr = str1[::str1.find(str2)]
print(newStr)

Answer 10

elpuoc

string step size =-1 as str2 cannot be found in str1 hence -1.

with a step size of minus 1, the string gets reversed

Question 11

string.upper

Answer 11

converts all the string to upper cases

Question 12

string.lower

Answer 12

converts all the strings to lower cases

Question 13

string.find

Answer 13

find the first character within the string and returns the index position of it.

if not found, return the value of 0

Question 14

string.capitalize

Answer 14

capitalizes the first part of the string only, subsequent strings are not included.

Question 15

string.index

Answer 15

similar to string.find but returns exception error when not found

Question 16

string.islower

Answer 16

Returns True if all characters in the string are lower case

Question 17

string.isupper

Answer 17

returns true if all characters in the string are upper case

Question 18

split the strings in accordance to the separator and returns it as an array

Answer 18

string.split

Question 19

swap both upper and lower cases

Answer 19

string.swapcases

Question 20

returns true of all the characters are digits

Answer 20

string.isdigit

Question 21

list1 = [1, “Python”, [3, 4], True]
list2 = list1[::-1] + list1[2]
print(list2)

Answer 21

[True, [3, 4], ‘Python’, 1, 3, 4]

Question 22

list1 = [1, "Python", [3, 4], True]
if 3 in list1:
    list2 = list1[2] * len(list1[2])
    print(list2)
elif [3, 4] in list1:
    print(list1[2][1])
else:
    print(list1[2])

Answer 22

Answer: 4

to call a list within a list

list[index with inner list][list index]

Question 23

list1 = ['d', 'c']
list2 = ['a', 'b’]
list1.reverse()
list2.reverse()
list3 = list1.extend(list2)
print(list3)

Answer 23

Answer: None

list methods are mostly functions and do not return any value, instead the act on the original list.

Question 24

Explain what does list methods doe

Answer 24

list methods are basically just functions and do not return and value. They just act to the list instead.

Question 25

Does list actually copy the physical list or do they copy the reference id only? Explain

Answer 25

Reference ID only. When you create a list, it creates a reference id to the variable. Var2 = Var1. Both are attached to the same id. Changing the list for 1 of the variable will change the other variable

Question 26

syntax for list comprehension

Answer 26

n for n in iterable if condition is true

Question 27

what is list comprehension equivalent to?

Answer 27

for x in array1: if condition = met: append x into a new array

Question 28

``` tuple1 = ('a', 'b', 'c') list1 = ['A', 'B', 'b', 'D', 'a'] result = [] for i in range(len(tuple1)): if tuple1[i] in list1: result.append(i) print(result ```

Answer 28

Result: [0,1]

Question 29

what data type does key of the dictionary can hold

Answer 29

strings, integers, tuples basically anything that is immutable No list

Question 30

if key contains list, what is the result

Answer 30

error

Question 31

dict1 = { 'a': [1], 'b': [2], } dict2 = { 'c': [3] } dict1.update(dict2) print(dict1)

Answer 31

``` { ‘a’:[1], ‘b’:[2], ‘c’:[3] } ```

Question 32

dict1 = { 'a': [1], 'b': [2], } dict2 = { 'a': [7], 'c': [3] } dict1.update(dict2) print(dict1)

Answer 32

{‘a’:[7], ‘b’:[2], ‘c’:[3]} updates and add to the key value specifically