Lab 1: Introduction to Python
¶
Welcome to Lab 1! Each week you will complete a lab assignment like this one. In this lab, you'll get
started with the Python programming language through numbers, names, and expressions.
As you go, please regularly select
Save and Checkpoint
from the
File
menu below the Jupyter logo
to save your work.
1. Numbers
¶
Quantitative information arises everywhere in data science. In addition to representing commands to
print out lines, expressions can represent numbers and methods of combining numbers. The expression
3.2500
evaluates to the number 3.25. (Run the cell and see.)
In [1]:
3.2500
Out[1]:
3.25
Notice that we didn't have to
print
. When you run a notebook cell, if the last line has a value, then
Jupyter helpfully prints out that value for you. However, it won't print out prior lines automatically. If
you want to print out a prior line, you need to add the
print
statement. Run the cell below to check.
In [2]:
print(2)
3
4
2
Out[2]:
4
Above, you should see that 4 is the value of the last expression, 2 is printed, but 3 is lost forever
because it was neither printed nor last.
You don't want to print everything all the time anyway. But if you feel sorry for 3, change the cell above
to print it.
1.1. Arithmetic
¶
The line in the next cell subtracts. Its value is what you'd expect. Run it.
In [3]:
3.25 - 1.5

Out[3]:
1.75
Many basic arithmetic operations are built in to Python. The textbook section on
Expressions
describes
all the arithmetic operators used in the course. The common operator that differs from typical math
notation is
**
, which raises one number to the power of the other. So,
2**3
stands for $2^3$ and
evaluates to 8.
The order of operations is what you learned in elementary school, and Python also has parentheses. For
example, compare the outputs of the cells below. Use parentheses for a happy new year!
In [4]:
2+6*5-6*3**2*2**3/4*7
Out[4]:
-724.0
In [5]:
2+(6*5-(6*3))**2*((2**3)/4*7)
Out[5]:
2018.0
In standard math notation, the first expression is
$$2 + 6 \times 5 - 6 \times 3^2 \times \frac{2^3}{4} \times 7,$$
while the second expression is
$$2 + (6 \times 5 - (6 \times 3))^2 \times (\frac{(2^3)}{4} \times 7).$$
Question 1.1.1.
Write a Python expression in this next cell that's equal to $5 \times (3 \frac{10}{11}) - 49 \frac{1}{3}
+ 2^{.5 \times 22} - \frac{7}{33}$. That's five times three and ten elevenths, minus 49 and a third,
plus two to the power of half of 22, minus 7 33rds. By "$3 \frac{10}{11}$" we mean $3+\frac{10}
{11}$, not $3 \times \frac{10}{11}$.