#!/usr/bin/env python
# coding: utf-8

# ## Understanding errors
# 
# Each snippet of the following code crashes. Run the code, **scroll to the bottom** of the error message, and read it. Just above the error message, you will also find the line of code where the error occurred!
# 
# Try to fix the errors! **Don't** copy your code from the previous labs, but make **minor** changes to the code here.
# 
# Hints: 
# - If you get a  `TypeError` mentioning `NoneType`, you likely forgot a `return` statement somewhere (and your function returns `None`).
# - If you encounter a `RecursionError` (infinite recursion), you likely forgot the base case or are calling the function `f` with the same argument (e.g. `n` or `lst`) rather than a smaller element (e.g. `n-1` or `lst[1:]`).
# - If you still can't find the error, sometimes it helps to add `print` statements to your function to see what the values of the variables are (don't forget to remove them at the end!). Or ask Ken how to use a debugger :)
# 
# ### Question 1
# 
# Printing all elements in a nested list

# In[ ]:


def print_list(lst):
    if type(lst) == list:
        for i in lst:
            print_list(lst[i])
    else:
        print(lst)

print_list([["hello"], "darkness", ["my", "old", ["friend"]]])


# ### Question 2
# 
# Removing all occurrences of a letter in a string

# In[ ]:


def removeLetter(s, letter):
    if s[0] == letter:
        return removeLetter(s[1:], letter)
    return s[0] + removeLetter(s[1:], letter)

removeLetter('abcaba', 'a')


# ### Question 3
# 
# Summing up all elements in a nested list

# In[ ]:


def sum_list(lst):
    if type(lst) == list:
        summ = 0
        for i in lst:
            summ += sum_list(i)
    else:
        return lst

print(sum_list([1, 2, [3, [4, 0], 5]]))


# ### Question 4
# 
# The following code should remove spaces from a string and print the result for the input `"Addis Coder"` and `"Don't worry be happy"`. But this code **does not work**.

# In[ ]:


def remove_spaces(string):
    new_string = ""
    for letter in string:
        if letter != " ":
            new_string += letter
    print(new_string)

    remove_spaces("Addis Coder")
    
remove_spaces("Don't worry be happy")


# ## List and Dictionary Comprehensions

# **Question 5**
# 
# Write a code that counts the occurrences of each numbers in a given interger list using the following methods.

# **a) Using any method**
# 

# In[53]:


# Given list
numbers = [1, 2, 2, 2, 3, 3, 3, 4, 4, 4, 4, 4]
#Write your code here


# **b) Using Dictionary Comprehension Method**
# 
# Hint: `lst.count(1)` counts how often 1 appears in `lst`.

# In[54]:


# Given list
numbers = [1, 2, 2, 2, 3,3 , 3, 4, 4, 4, 4, 4]

#Write your code here


# #### Question 6
# 
# There is no question 6.

# **Question 7**
# 
# Write a code that extracts the first character of each word in a sentence using list comprehensions. 
# 
# Hint: You can use `string.split()` to turn a string into a list of words.
# 

# In[34]:


# Given sentence
sentence = "AddisCoder is helping Ethiopian HighSchoolers to achieve their dreams."

# Write your code for method here


# **Question 8**
# 
# Write a code that takes list of strings and creates a new list with the length of each string using list comprehension.  
# 

# In[35]:


#Given list of strings

string_list = ["Heather", "Biniyam", "Ken", "Alex", "Yeabsira", "Hana"]

#Write your code here


# **Question 9**
# 
# Write a code that finds all the common elements between two given lists using a list comprehension.

# In[38]:


#Given two lists

list1 = [5, 2, 3, 4, 6, 8, 7, 9]
list2 = [4, 5, 6, 7, 8, 3, 1, 10]

#Write your code here


# **Question 10**
# 
# Write a code that finds all anagrams of a given word from a list of words using the following two methods.
# 
# "An **anagram** is a word or phrase formed by rearranging the letters of a different word or phrase, 
# typically using all the original letters exactly once." 
# 
# Look here for more info: 
# https://en.wikipedia.org/wiki/Anagram

# **a) Using any method**

# In[44]:


# Write your code for method 'a' here
def is_anagram(word1, word2):
    pass

# Given word and list of words
given_word = "listen"
word_list = ["enlist", "silent", "hello", "inlets", "world", "tinsel"]


# Print the list of anagrams




# **b) Using List Comprehensions**

# In[46]:


# Write your code for method 'b' here

def is_anagram(word1, word2):
    pass

# Given word and list of words
given_word = "listen"
word_list = ["enlist", "silent", "hello", "inlets", "world", "tinsel"]


# Print the list of anagrams



# **Question 11**
# 
# Write a code that finds a Transpose Matrix of a given Matrix by using the following two methods.
# 
# Transpose matrix is a matrix that filiped over its diagonal. This means the that is, 
# the row and column indices of the matrix are switched. 
# 
# Read to learn more about Transpose Matrix: https://en.wikipedia.org/wiki/Transpose
# 

# **a) Use any method**

# In[48]:


matrix = [[1, 2, 3, 4], [4, 5, 6, 8]]

#Write your code here


# **b) List Comprehensions method**

# In[ ]:


matrix = [[1, 2, 3, 4], [4, 5, 6, 8]]

#Write your code here