How to Create a Sequence of Linearly Increasing Values with Numpy Arange?

Problem: How to create a sequence of linearly increasing values?

Solution: Use NumPy’s arange() function.

The np.arange([start,] stop[, step]) function creates a new NumPy array with evenly-spaced integers between start (inclusive) and stop (exclusive). The step size defines the difference between subsequent values. For example, np.arange(1, 6, 2) creates the NumPy array [1, 3, 5].

import numpy as np

# np.arange(stop)
>>> np.arange(10)
array([0, 1, 2, 3, 4, 5, 6, 7, 8, 9])

# np.arange(start, stop)
>>> np.arange(2, 10)
array([2, 3, 4, 5, 6, 7, 8, 9])

# np.arange(start, stop, step)
>>> np.arange(2, 10, 2)
array([2, 4, 6, 8])

# np.arange(start, stop, step, dtype)
>>> np.arange(2, 10, 2, float)
array([2., 4., 6., 8.])

Related Video NumPy Arange

NumPy Data Science Puzzle

Can you solve the following puzzle regarding the NumPy arange function:

import numpy as np

# save $122.50 per month
x = 122.5
net_wealth = np.arange(0, 1000, x)

# how long to save > $1000?
print(len(net_wealth))

What is the output of this puzzle?

Numpy is a popular Python library for data science focusing on linear algebra.

This puzzle is about the numpy arange function. The arange function is everywhere in data science.

You might know the Python built-in range(x,y,z) function that creates a sequence of linear progressing values. The sequence starts from x, increases the values linearly by y, and ends if the value becomes larger than z.

The arange(x,y,z) function is similar but creates a numpy array and works with float numbers as well.

Note that a common mistake in this puzzle is to not account for the first value of the array: 0.

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Solution

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