FAQ: Linear Regression - Put it Together

Frequently Asked Questions Python FAQ
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This community-built FAQ covers the “Put it Together” exercise from the lesson “Linear Regression”.

Paths and Courses
This exercise can be found in the following Codecademy content:

Data Science

Machine Learning

FAQs on the exercise Put it Together

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2

Hi guys,
There is something I haven’t understood about the exercise: in the step_gradient function, the next guesses are defined by b=b_current - 0.01*b_gradient. As far as I know, the gradient is a slope, so how does an x-axis value minus a slope produce another x-axis value? Thanks for your reply!

2 Likes
3

In Step 4 of this lesson, the step_gradient function is called like this:

b, m = step_gradient(months, revenue, b, m)

Why is that?

4

Generally, gradient represents the direction in which the function increases fastest. By adding to (b, m) a vector in the direction opposite to the gradient, we can expect that the function (loss) will be smaller. (However, if the step is too large, it may go past the point of minimizing the loss, so it is adjusted by the learning rate.)

1 Like
5

In Python, we can assign values to multiple variables by separating variables with commas.

a, b = 1, 2

print(a)  # 1
print(b)  # 2

In Step 3, the return value of the function step_gradient() is set as a pair (tuple or list), so it’s components are assigned to b and m in one line.