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

# # Python 3

# ## Functions

# In[1]:


import math
def euclidean_distance(x1, y1, x2, y2):
    return math.sqrt((x1 - x2) ** 2 + (y1-y2) ** 2)


# In[2]:


euclidean_distance(0,0,1,1)


# We can unpack a list or tuple into positional arguments using a star `*`:

# In[3]:


values_list = [0,0,1,1]
euclidean_distance(*values_list)


# In[4]:


values_tuple = (0,0,1,1)
euclidean_distance(*values_tuple)


# Similarly, we can use double star `**` to unpack a dictionary into keyword arguments.

# In[11]:


values_dict = { 'x1': 0, 'y1': 0, 'x2': 1, 'y2': 1 }
euclidean_distance(**values_dict)


# In[13]:


list(zip([1,2,3,4,5,6]))


# ## Comprehensions
# With <a href="http://python-3-patterns-idioms-test.readthedocs.io/en/latest/Comprehensions.html">comprehensions</a>, we can build a sequence based on another iterable. 

# In[6]:


# List comprehension
[num ** 2 for num in range(-10, 11)]


# In[7]:


[num ** 2 for num in range(-10, 11) if num > 0]


# In[8]:


# Set comprehension
names = [ 'Bob', 'JOHN', 'alice', 'bob', 'ALICE', 'J', 'Bob' ]
{ name[0].upper() + name[1:].lower() for name in names if len(name) > 1 }


# ### Dictionary comprehension

# In[9]:


s = "Action Is Eloquence"
counts = dict()
for char in s:
    counts[char] = counts.get(char, 0) + 1
counts


# In[10]:


freq = { 
    k.lower() : counts.get(k.lower(), 0) + counts.get(k.upper(), 0)
    for k in counts.keys() if k.isalpha()
}
freq