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CS351 - Cloud Computing - Solved
# Python
Solve the following problems in Python 3.6+ .
In addition to making sure that your code gives the correct solution, each solution must meet the following conditions.
1. Your function parameters must be [type-
hinted](https://docs.python.org/3.6/library/typing.html]). These need not be perfect, but should be generally correctly describe your input
and output.
2. Your functions must have a doc-string describing what the function does. Keep is succinct and concise.
3. Use a auto-formatter such as
[black](https://pypi.org/project/black/) or [autopep8](https://pypi.org/project/autopep8/).
4. Write atleast 2 simple
[doctests](https://docs.python.org/3.6/library/doctest.html) per solution to verify that your code is working correctly.
5. Use descriptive variable names.
Here is an example of what your code should look like.
For example ```python
from typing import List
def average(num_list: List[int]) -> float: """Finds the average of a list of numbers.
doctests:
>>> average([1,2,3,4,5])
3.0
>>> average([0])
0.0 """
list_sum = sum(num_list) list_size = len(num_list) avg = list_sum/list_size return avg
if __name__ == "__main__":
import doctest doctest.testmod()
```
## Problem 1
Write a function to break down a string into a list of characters. ```
Input: "abc"
Output: ['a','b','c']
```
## Problem 2
Write a function to reverse output of the problem 1 back into a string
```
Input: ['a','b','c']
Output: "abc"
```
## Problem 3
Write a function generate a list of n random numbers.
Use the inbuilt `random` module.
```
Input: 5
Output: [5,2,3,1,5]
```
## Problem 4
Write a function a sort a given list of numbers in descending order.
```
Input: [1,2,3,4,5]
Output: [5,4,3,2,1]
```
## Problem 5
Write a function to get frequency of each numbers in a list of numbers. Use a python `dict` to solve this.
```
Input: [1,1,3,2,3,2,3,2,2]
Output: {1: 2, 3: 3, 2: 4}
```
## Problem 6
Write a function to get all the unique elements from given list. Your solution must use `set` to solve this.
```
Input: [1,1,3,2,3,2,3,2,2]
Output: {1,2,3}
```
## Problem 7
Write a function to get the first repeating element from list. Your solution must use `set` to solve this.
```
Input: [1,2,3,4,5,1,2]
Output: 1
```
## Problem 8
Write a function that takes an integer n and output a `dict` containing keys from 0,2 ... to n and each key is mapped to a list containing the square and cube of the number.
```
Input: 3
Output:
{
0:[0,0],
1:[1,1],
2:[4,8],
3:[9,27]
}
```
## Problem 9
Given two lists of equal size, write a function to create tuples of each consecutive element having same index. Use `zip` in some capacity to solve this.
```
Input: [1,2,3,4], ['a','b','c','d']
Output: [(1,'a'), (2,'b'), (3,'c'), (4,'d')]
```
## Problem 10
Write a function that uses list comprehension to generate the squares of 0 to n.
```
Input : 5
Output : [0, 1, 4, 9, 16, 25]
```
## Problem 11
Write a function that uses dictionary comprehension to generate a mapping from (0 to n) to their squares.
```
Input : 5
Output : {0:0, 1:1, 2:4, 3:9, 4:16, 5:25}
```
## Problem 12.
Write a `class` such that :
1. The initializer takes an arbitrary list of atomic values as input and saves it in a instance variable.
2. Has a method called `apply` which has the following functionality: 1. Accepts a function as a parameter. You can use a lambda function.
2. Applies the function to saved list and return the output. The instance variable must not be modified.
3. If it fails `raise` an `Exception` with a custom error message. You can use `try` and `except` here.
```python def sq(x): return x**2 c1 = MyClass([1,2,3,4])
print(c1.apply(lambda x:x**2))
[1,4,9,16]
c2 = MyClass(['a','b','c']) c2.apply(sq)
--------------------------------------------------------------------------
TypeError Traceback (most recent call last)
....
....
Exception: Custom Error
```
## Problem 13
Write a function takes as input a list of words and upper-cases each word. Use `functools.map` in some capacity to solve this.
```
Input : ['aa','bb','cd','e']
Output : ['AA', 'BB', 'CD', 'E']
```
## Problem 14:
Write a function to find the product of all the numbers in a list using `functools.reduce` in some capacity.
```
Input : [1,2,3,4,5]
Output : 120
```
1. Your function parameters must be [type-
hinted](https://docs.python.org/3.6/library/typing.html]). These need not be perfect, but should be generally correctly describe your input
and output.
2. Your functions must have a doc-string describing what the function does. Keep is succinct and concise.
3. Use a auto-formatter such as
[black](https://pypi.org/project/black/) or [autopep8](https://pypi.org/project/autopep8/).
4. Write atleast 2 simple
[doctests](https://docs.python.org/3.6/library/doctest.html) per solution to verify that your code is working correctly.
5. Use descriptive variable names.
Here is an example of what your code should look like.
For example ```python
from typing import List
def average(num_list: List[int]) -> float: """Finds the average of a list of numbers.
doctests:
>>> average([1,2,3,4,5])
3.0
>>> average([0])
0.0 """
list_sum = sum(num_list) list_size = len(num_list) avg = list_sum/list_size return avg
if __name__ == "__main__":
import doctest doctest.testmod()
```
## Problem 1
Write a function to break down a string into a list of characters. ```
Input: "abc"
Output: ['a','b','c']
```
## Problem 2
Write a function to reverse output of the problem 1 back into a string
```
Input: ['a','b','c']
Output: "abc"
```
## Problem 3
Write a function generate a list of n random numbers.
Use the inbuilt `random` module.
```
Input: 5
Output: [5,2,3,1,5]
```
## Problem 4
Write a function a sort a given list of numbers in descending order.
```
Input: [1,2,3,4,5]
Output: [5,4,3,2,1]
```
## Problem 5
Write a function to get frequency of each numbers in a list of numbers. Use a python `dict` to solve this.
```
Input: [1,1,3,2,3,2,3,2,2]
Output: {1: 2, 3: 3, 2: 4}
```
## Problem 6
Write a function to get all the unique elements from given list. Your solution must use `set` to solve this.
```
Input: [1,1,3,2,3,2,3,2,2]
Output: {1,2,3}
```
## Problem 7
Write a function to get the first repeating element from list. Your solution must use `set` to solve this.
```
Input: [1,2,3,4,5,1,2]
Output: 1
```
## Problem 8
Write a function that takes an integer n and output a `dict` containing keys from 0,2 ... to n and each key is mapped to a list containing the square and cube of the number.
```
Input: 3
Output:
{
0:[0,0],
1:[1,1],
2:[4,8],
3:[9,27]
}
```
## Problem 9
Given two lists of equal size, write a function to create tuples of each consecutive element having same index. Use `zip` in some capacity to solve this.
```
Input: [1,2,3,4], ['a','b','c','d']
Output: [(1,'a'), (2,'b'), (3,'c'), (4,'d')]
```
## Problem 10
Write a function that uses list comprehension to generate the squares of 0 to n.
```
Input : 5
Output : [0, 1, 4, 9, 16, 25]
```
## Problem 11
Write a function that uses dictionary comprehension to generate a mapping from (0 to n) to their squares.
```
Input : 5
Output : {0:0, 1:1, 2:4, 3:9, 4:16, 5:25}
```
## Problem 12.
Write a `class` such that :
1. The initializer takes an arbitrary list of atomic values as input and saves it in a instance variable.
2. Has a method called `apply` which has the following functionality: 1. Accepts a function as a parameter. You can use a lambda function.
2. Applies the function to saved list and return the output. The instance variable must not be modified.
3. If it fails `raise` an `Exception` with a custom error message. You can use `try` and `except` here.
```python def sq(x): return x**2 c1 = MyClass([1,2,3,4])
print(c1.apply(lambda x:x**2))
[1,4,9,16]
c2 = MyClass(['a','b','c']) c2.apply(sq)
--------------------------------------------------------------------------
TypeError Traceback (most recent call last)
....
....
Exception: Custom Error
```
## Problem 13
Write a function takes as input a list of words and upper-cases each word. Use `functools.map` in some capacity to solve this.
```
Input : ['aa','bb','cd','e']
Output : ['AA', 'BB', 'CD', 'E']
```
## Problem 14:
Write a function to find the product of all the numbers in a list using `functools.reduce` in some capacity.
```
Input : [1,2,3,4,5]
Output : 120
```
