A Tutorial by Jacob Gerace
#A variable stores a piece of data and gives it a name
answer = 42
#answer contained an integer because we gave it an integer!
is_it_thursday = True
is_it_wednesday = False
#these both are 'booleans' or true/false values
pi_approx = 3.1415
#This will be a floating point number, or a number containing digits after the decimal point
my_name = "Jacob"
#This is a string datatype, the name coming from a string of characters
#Data doesn't have to be a singular unit
#p.s., we can print all of these with a print command. For Example:
print(answer)
print(pi_approx)
42 3.1415
#What if we want to store many integers? We need a list!
prices = [10, 20, 30, 40, 50]
#This is a way to define a list in place. We can also make an empty list and add to it.
colors = []
colors.append("Green")
colors.append("Blue")
colors.append("Red")
print(colors)
#We can also add unlike data to a list
prices.append("Sixty")
#As an exercise, look up lists in python and find out how to add in the middle of a list!
print(prices)
#We can access a specific element of a list too:
print(colors[0])
print(colors[2])
#Notice here how the first element of the list is index 0, not 1!
#Languages like MATLAB are 1 indexed, be careful!
#In addition to lists, there are tuples
#Tuples behave very similarly to lists except that you can't change them
# after you make them
#An empty Tuple isn't very useful:
empty_tuple = ()
#Nor is a tuple with just one value:
one_tuple = ("first",)
#But tuples with many values are useful:
rosa_parks_info = ("Rosa", "Parks", 1913, "February", 4)
#You can access tuples just like lists
print(rosa_parks_info[0] + " " + rosa_parks_info[1])
# You cannot modify existing tuples, but you can make new tuples that extend
# the information.
# I expect Tuples to come up less than lists. So we'll just leave it at that.
['Green', 'Blue', 'Red'] [10, 20, 30, 40, 50, 'Sixty'] Green Red
float1 = 5.75
float2 = 2.25
#Addition, subtraction, multiplication, division are as you expect
print(float1 + float2)
print(float1 - float2)
print(float1 * float2)
print(float1 / float2)
#Here's an interesting one that showed up in the first homework in 2017. Modulus:
print(5 % 2)
8.0 3.5 12.9375 2.5555555555555554 1
#Just about every standard math function on a calculator has a python equivalent pre made.
#however, they are from the 'math' package in python. Let's add that package!
import math
print(math.log(float1))
print(math.exp(float2))
print(math.pow(2,5))
# There is a quicker way to write exponents if you want:
print(2.0**5.0)
#Like in MATLAB, you can expand the math to entire lists
list3 = [1, 2, 3, 4, 5]
print(2 * list3)
#We can plot easily in Python like in matlab, just import the relevant package!
%matplotlib inline
import matplotlib.pyplot as plt
x_vals = [-2, -1, 0, 1, 2]
y_vals = [-4, -2, 0, 2, 4]
plt.plot(x_vals, y_vals)
1.749199854809259 9.487735836358526 32.0 32.0
[<matplotlib.lines.Line2D at 0x115181f28>]
#Repeat code until a conditional statement ends the loop
#Let's try printing a list
fib = [1, 1, 2, 3, 5, 8]
#While loops are the basic type
i = 0
while(i < len(fib)):
print(fib[i])
i = i + 1
#In matlab, to do the same thing you would have the conditional as: counter < (length(fib) + 1)
#This is because matlab starts indexing at 1, and python starts at 0.
#The above type of loop is so common that the 'for' loop is the way to write it faster.
print("Let's try that again")
#This is most similar to for loops in matlab
for i in range(0, len(fib)) :
print(fib[i])
print("One more time:")
#Or you can do so even neater
for e in fib:
print(e)
1 1 2 3 5 8 Let's try that again 1 1 2 3 5 8 One more time: 1 1 2 3 5 8
If you still feel VERY lost: Code Academy
If you want a good reference site: Official Python Reference
If you want to learn python robustly: Learn Python the Hard Way
Feel free to contact me at: jgerace (at) nd (dot) edu