Exercises

1) Variables and Print 2) Functions 3) Control structures 4) List 5) File 6) Text processing 7) Misc

For some questions, Python program with assert statements is provided to automatically test your solution in the exercise_files directory - for ex: Q2a - length of integer numbers. The directory also has sample input text files.

You can also solve these exercises on repl.it, with an option to submit them for review.

1) Variables and Print

Q1a) Ask user information, for ex: name, department, college etc and display them using print function

# Sample of how program might ask user input and display output afterwards
$ ./usr_ip.py 
Please provide the following details
Enter your name: learnbyexample
Enter your department: ECE
Enter your college: PSG Tech

------------------------------------
Name       : learnbyexample
Department : ECE
College    : PSG Tech

2) Functions

Q2a) Returns length of integer numbers

>>> len_int(962306349871524124750813401378124)
33
>>> len_int(+42)
2
>>> len_int(-42)
3

# bonus: handle -ve numbers and check for input type
>>> len_int(-42)
2
# len_int('a') should give
TypeError: provide only integer input

Q2b) Returns True/False - two strings are same irrespective of lowercase/uppercase

>>> str_cmp('nice', 'nice')
True
>>> str_cmp('Hi there', 'hi there')
True
>>> str_cmp('GoOd DaY', 'gOOd dAy')
True
>>> str_cmp('foo', 'food')
False

Q2c) Returns True/False - two strings are anagrams (assume input consists of alphabets only)

>>> str_anagram('god', 'Dog')
True
>>> str_anagram('beat', 'table')
False
>>> str_anagram('Tap', 'paT')
True
>>> str_anagram('beat', 'abet')
True

Q2d) Returns corresponding integer or floating-point number (See Number and String data types chapter for details)

# number input
>>> num(3)
3
>>> num(0x1f)
31
>>> num(3.32)
3.32

# string input
>>> num('123')
123
>>> num('-78')
-78
>>> num(" 42  \n ")
42
>>> num('3.14')
3.14
>>> num('3.982e5')
398200.0

>>> s = '56'
>>> num(s) + 44
100

Other than integer or floating, only string data type should be accepted. Also, provide custom error message if input cannot be converted

# num(['1', '2.3'])
TypeError: not a valid input

# num('foo')
ValueError: could not convert string to int or float

3) Control structures

Q3a) Write a function that returns

'Good' for numbers divisible by 7
'Food' for numbers divisible by 6
'Universe' for numbers divisible by 42
'Oops' for all other numbers
Only one output, divisible by 42 takes precedence

>>> six_by_seven(66)
'Food'
>>> six_by_seven(13)
'Oops'
>>> six_by_seven(42)
'Universe'
>>> six_by_seven(14)
'Good'
>>> six_by_seven(84)
'Universe'
>>> six_by_seven(235432)
'Oops'

bonus: use a loop to print number and corresponding string for numbers 1 to 100

1 Oops
2 Oops
3 Oops
4 Oops
5 Oops
6 Food
7 Good
...
41 Oops
42 Universe
...
98 Good
99 Oops
100 Oops

Q3b) Print all numbers from 1 to 1000 which reads the same in reversed form in both binary and decimal format

$ ./dec_bin.py 
1 1
3 11
5 101
7 111
9 1001
33 100001
99 1100011
313 100111001
585 1001001001
717 1011001101

bonus: add octal and hexadecimal checks as well

$ ./dec_bin_oct.py 
1 0b1 0o1
3 0b11 0o3
5 0b101 0o5
7 0b111 0o7
9 0b1001 0o11
585 0b1001001001 0o1111

$ ./dec_bin_oct_hex.py 
1 0b1 0o1 0x1
3 0b11 0o3 0x3
5 0b101 0o5 0x5
7 0b111 0o7 0x7
9 0b1001 0o11 0x9

4) List

Q4a) Write a function that returns product of all numbers of a list

>>> product([1, 4, 21])
84
>>> product([-4, 2.3e12, 77.23, 982, 0b101])
-3.48863356e+18

bonus: works on any kind of iterable

>>> product((-3, 11, 2))
-66
>>> product({8, 300})
2400
>>> product([234, 121, 23, 945, 0])
0
>>> product(range(2, 6))
120
# can you identify what mathematical function the last one performs?

Q4b) Write a function that returns nth lowest number of a list (or iterable in general). Return the lowest if second argument not specified

Note that if a list contains duplicates, they should be handled before determining nth lowest

>>> nums = [42, 23421341, 234.2e3, 21, 232, 12312, -2343]
>>> nth_lowest(nums, 3)
42
>>> nth_lowest(nums, 5)
12312
>>> nth_lowest(nums, 15)
Traceback (most recent call last):
  File "<stdin>", line 1, in <module>
  File "<stdin>", line 2, in nth_lowest
IndexError: list index out of range

>>> nums = [1, -2, 4, 2, 1, 3, 3, 5]
>>> nth_lowest(nums)
-2
>>> nth_lowest(nums, 4)
3
>>> nth_lowest(nums, 5)
4

>>> nth_lowest('unrecognizable', 3)
'c'
>>> nth_lowest('abracadabra', 4)
'd'

Q4c) Write a function that accepts a string input and returns slices

if input string is less than 3 characters long, return a list with input string as the only element
otherwise, return list with all string slices greater than 1 character long
order of slices should be same as shown in examples below

>>> word_slices('i')
['i']
>>> word_slices('to')
['to']

>>> word_slices('are')
['ar', 'are', 're']
>>> word_slices('table')
['ta', 'tab', 'tabl', 'table', 'ab', 'abl', 'able', 'bl', 'ble', 'le']

5) File

Q5a) Print sum of all numbers from a file containing only single column and all numbers

$ cat f1.txt 
8
53
3.14
84
73e2
100
2937

$ ./col_sum.py 
10485.14

Q5b) Print sum of all numbers (assume only positive integer numbers) from a file containing arbitrary string

$ cat f2.txt 
Hello123 World 35
341 2
Good 13day
How are 1784 you

$ ./extract_sum.py 
2298

Q5c) Sort file contents in alphabetic order based on each line's extension

extension here is defined as the string after the last . in the line
if line doesn't have a ., those lines should come before lines with .
sorting should be case-insensitive
use rest of string as tie-breaker if there are more than one line with same extension
assume input file is ASCII encoded and small enough to fit in memory

bonus: instead of printing results to stdout, change the input file itself with sorted result

$ cat f3.txt
power.Log
foo.123.txt
list
report_12.log
baz.TXT
hello.RB
loop.do.rb
Fav_books

$ ./sort_by_ext.py
Fav_books
list
power.Log
report_12.log
hello.RB
loop.do.rb
baz.TXT
foo.123.txt

6) Text processing

Q6a) Check if two words are same or differ by only one character (irrespective of case), input strings should have same length

7) Misc

Q7a) Play a song (hint use subprocess module)

Q7b) Open a browser along with any link, for ex: https://github.com/learnbyexample/Python_Basics (hint use webbrowser module)

Q7c) Write a function that

accepts a filesystem path(default) or a url(indicated by True as second argument)
returns the longest word(here word is defined as one or more consecutive sequence of alphabets of either case)
assume that input encoding is utf-8 and small enough to fit in memory and that there's only one distinct longest word

>>> ip_path = 'poem.txt'
>>> longest_word(ip_path)
'Violets'

>>> ip_path = 'https://www.gutenberg.org/files/60/60.txt'
>>> longest_word(ip_path, True)
'misunderstandings'

For reference solutions, see exercise_solutions directory

Exercises

Exercises

1) Variables and Print

2) Functions

3) Control structures

4) List

5) File

6) Text processing

7) Misc

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