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

# # AddisCoder 2023: Week 2, Day 5
# ## Syntactic Sugar: List Comprehensions, Strings functions, Debugging
# 
# Taught by Alex Krentsel (alex.krentsel@gmail.com)
# 
# Python has a bunch of nice language features that let you do things more easily.

# ## List Comprehensions

# In[39]:


# How do we know how to make a list of all the numbers from 1 to 20?

# We can use a for loop!
nums = []
for i in range(1,21):
    nums.append(i)
print(nums)


# In[ ]:


# Python has some nice built-in features to do this more easily. Specifically, we can use list comprehensions.
# List comprehensions are a way to create lists in Python. They are very useful and are used often in Python code.
# Here is an example of a list comprehension that does the same thing as the for loop above.
nums = [i for i in range(1,21)]


# In[40]:


# We can also use list comprehensions to create lists of strings.

# Advanced example: we can use the chr() function to convert an integer to a character.
# The ord() function converts a character to an integer.
print(ord('a'))
print(ord('z'))


# In[42]:


print(chr(97))
print(chr(98))


# In[ ]:


# Here is an example of a list comprehension that creates a list of the first 10 letters of the alphabet.
letters = [chr(i) for i in range(ord('a'),ord('k'))]


# In[44]:


# We can use range as usual to change the step size.

countdown = [n for n in range(10,0,-1)]
print(countdown)


# In[49]:


# We can also use if statements in list comprehensions
lst = [x for x in range(10) if x%2 == 0]
print(lst)


# More examples to practice...

# In[45]:


# Making a list containing 10 2s?
lst = []
for i in range(10):
    lst.append(2)
print(lst)


# In[46]:


lst = [2 for i in range(10)]
print(lst)


# In[47]:


# Multiple of 2 
lst = [2*x for x in range(0,10)]
lst


# In[48]:


# Make a new list modifying a different list
lst2 = [l+1 for l in lst]
lst2


# ## Dictionary Comprehensions

# In[37]:


# We can do the same thing for dictionaries
powers_of_2 = {x:2**x for x in range(10)}
even_powers_of_2 = {x:2**x for x in range(10) if x%2 == 0}


# In[50]:


# Here's a handy example: let's make a dictionary that maps from a character's code to the character itself.

code2char = {i:chr(i) for i in range(ord('a'),ord('z')+1)}
print(code2char)


# ## Final Wrapup
# 
# A few other topics we should talk about before we wrap up with standard Python stuff. 

# In[51]:


# Ternary Operator

# The ternary operator is a way to write if statements in one line. 
# The syntax is: <value if true> if <condition> else <value if false>

# Example of a use of ternary:
# We want to print "even" if a number is even and "odd" if a number is odd.

def even_or_odd(n):
    return "even" if n % 2 == 0 else "odd"

print(even_or_odd(7))
print(even_or_odd(42))


# ## Useful String Functions

# In[ ]:


# We can use the split() function to split a string into a list of strings.
# We pass what "delimiter" we want to split on
sentence = "This is a sentence made up of some words."
words = sentence.split(" ")
print(words)


# In[54]:


names_string = "Aku,Abraham,Binyam,Georg,Liya"
name_list = names_string.split(",")
print(name_list)


# In[56]:


# We can do the opposite too.
# If we have a list, we can join the list together into a single string:

print(words)
print("-".join(words))
print(".".join(words))
print("ALEX".join(words))


# In[61]:


# Printing using f-strings (formatted strings)

# We can use f-strings to print strings with variables in them.
# We put an f before the string and then put the variable in curly braces.
name = "Alex"
print(f"Hello, my name is {name}")

greeting = "Hi"
print(f"{greeting}, my name is {name}")


# In[62]:


# It doesn't have to be inside of a print statement.
# We can use f-strings to create strings.
name = "Alex"
announcement = f"Hello, my name is {name}"
print(announcement)


# In[65]:


# Going to uppercase or lowercase,

sample_str = "My name is Alex"
print(sample_str)
print(sample_str.upper())
print(sample_str.lower())

# We can also use the title() function to capitalize the first letter of each word.
print(sample_str.title())

# And many many more functions. 


# ## How to Debug your Code
# 
# Let's look at an error together.

#