Assignment 2: Strings, Lists & Functions

Tasks

Task 1

Study a string method that split each word in a string into list of words. Then, write a function that takes two strings as an input, one is a word s, one is delimiter d.

Delimiter is the repeating characters separating words, e.g., comma. See examples for more details.

# Example 1
'hello world this is the test message' -> ['hello', 'world', 'this', 'is', 'the', 'test', 'message']

# Example 2
'1,2,3,4,5,,' -> ['1', '2', '3', '4', '5', '', '']

Task 2

Write a function that takes a string s and two integers: a and b as inputs and returns a new string. The new string comes from concatenating two strings:

1. First a characters from the left of the string in reversed order.

2. Last b characters from the right of the string in the same order.

Guarantee that len(s) >= a + b always.

# Example 1
s = 'javascript is a weird language.'
a = 6
b = 4
f2(s, a, b) -> 'csavajage.'

Task 3

Study a string method that join each string from a list of strings. See examples for more details.

Write a function that takes a string d and a list of strings c as inputs. The string d will be the delimiter joining every string in c in reversed order.

# Example 1
s = '58'
c = ['Som', 'Wang', 'Coke', 'James']
f3(s, c) -> James58Coke58Wang58Som

Task 4: Conversion

Write a function that takes two integers a, b as inputs. The function returns a digit-concatenated integers.

# Example 1
n1 = 59
n2 = 2678

f4(n1, n2) -> 592678  # in integer, not string

Task 5: n-Tuple

A tuple is an immutable data type in Python, it works almost like the list, but you can’t add or remove elements from it. It is useful when you have n-dimensional data, e.g., 3D coordinate.

You can create a tuple in Python with parentheses:

new_tuple = (2.5, 0.0, 6.8)
# This is called '3-tuple' because it has 3 elements.
# Sometimes, you might see it be called as '3-vector'.

You can access, index, slice it like lists and strings. Tuples are data types in Python, so you can put them in the list, which will make it “a list of tuples”

Try creating a function that takes a list of 3-tuples and return a sorted version of it. Try both sorting in ascending order (default) and descending order.

When Python sorts a tuple, it compares the leftmost element of each first. If they are equal, then it compares the next pair of element and so on.

Try sort this as an example.

# A list of 3D coordinates
[(1, 2, 3), (9, 8, 9), (60, 5, 5), (1, 7, 8), (1, 2, 2), (1, 1, 1), (-9, 0, 0)]

Template

# Task 1
def f1(s, d):
    # do something
    # return something

# Task 2
def f2(s, a, b):
    # do something
    # return something
    
# Task 3
def f3(d, c):
    # do something
    # return something