data8/_build/jupyter_execute/content/chapters/04/3/Comparison.py

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

# # Comparisons
# 
# Boolean values most often arise from comparison operators. Python includes a variety of operators that compare values. For example, `3` is larger than `1 + 1`.

# In[1]:


3 > 1 + 1


# The value `True` indicates that the comparison is valid; Python has confirmed this simple fact about the relationship between `3` and `1+1`. The full set of common comparison operators are listed below.
# 
# | Comparison         | Operator | True example | False Example |
# |--------------------|----------|--------------|---------------|
# | Less than          | <        | 2 < 3        | 2 < 2         |
# | Greater than       | >        | 3>2          | 3>3           |
# | Less than or equal | <=       | 2 <= 2       | 3 <= 2        |
# | Greater or equal   | >=       | 3 >= 3       | 2 >= 3        |
# | Equal              | ==       | 3 == 3       | 3 == 2        |
# | Not equal          | !=       | 3 != 2       | 2 != 2        |

# An expression can contain multiple comparisons, and they all must hold in order for the whole expression to be `True`. For example, we can express that `1+1` is between `1` and `3` using the following expression.

# In[2]:


1 < 1 + 1 < 3


# The average of two numbers is always between the smaller number and the larger number. We express this relationship for the numbers `x` and `y` below. You can try different values of `x` and `y` to confirm this relationship.

# In[3]:


x = 12
y = 5
min(x, y) <= (x+y)/2 <= max(x, y)


# Strings can also be compared, and their order is alphabetical. A shorter string is less than a longer string that begins with the shorter string.

# In[4]:


"Dog" > "Catastrophe" > "Cat"