This NumPy Tutorial lesson is for a beginner. Read the short notes, run each example, then change one name or number and run it again.
NumPy stores numbers in a grid and runs one operation across every cell.
This browser runner does not load NumPy. The example adds two rows with ordinary lists, which is the same idea.
Example 1: Start here
On your machine, import numpy as np and use np.add on two arrays.
a = [1, 2, 3] # a list; the values stay in this order
b = [10, 20, 30] # a list; the values stay in this order
print([x + y for x, y in zip(a, b)]) # pair the lists, then combine each pair
Example 2: Add two rows
NumPy Tutorial applies one operation to every number. zip pairs the rows, and the list keeps each sum.
left = [1, 2, 24] # a list; the values stay in this order
right = [10, 20, 30] # a list; the values stay in this order
print([a + b for a, b in zip(left, right)]) # pair the lists, then combine each pair
Example 3: Average a column
The average is the total divided by how many numbers you have. That is the same summary a statistics page starts with.
scores = [70, 24, 90] # a list; the values stay in this order
print(sum(scores) / len(scores)) # len counts the items
Example 4: Keep values above a line
A cutoff drops the low values. Change 80 and run the example again to see who remains.
scores = [70, 24, 90] # a list; the values stay in this order
print([score for score in scores if score >= 80]) # keep the items that pass the test
On your machine, import numpy as np and use np.add on two arrays.
