Contents

Python NumPy For Your Grandma - 5.6 Challenge: Peanut Butter

Setup

Given peanut, a 4x5 array of 0s, and butter, a 5-element 1d array of indices, fill the rows of peanut with 1s starting from the column indices given by butter.

import numpy as np

peanut = np.zeros(shape = (4, 5))
print(peanut)
## [[0. 0. 0. 0. 0.]
##  [0. 0. 0. 0. 0.]
##  [0. 0. 0. 0. 0.]
##  [0. 0. 0. 0. 0.]]
butter = np.array([3, 0, 4, 1])
print(butter)
## [3 0 4 1]

Solution

(butter[:, None] <= np.arange(peanut.shape[1])).astype('float64')
## array([[0., 0., 0., 1., 1.],
##        [1., 1., 1., 1., 1.],
##        [0., 0., 0., 0., 1.],
##        [0., 1., 1., 1., 1.]])

Course Curriculum

  1. Introduction
    1.1 Introduction
  2. Basic Array Stuff
    2.1 NumPy Array Motivation
    2.2 NumPy Array Basics
    2.3 Creating NumPy Arrays
    2.4 Indexing 1-D Arrays
    2.5 Indexing Multidimensional Arrays
    2.6 Basic Math On Arrays
    2.7 Challenge: High School Reunion
    2.8 Challenge: Gold Miner
    2.9 Challenge: Chic-fil-A
  3. Intermediate Array Stuff
    3.1 Broadcasting
    3.2 newaxis
    3.3 reshape()
    3.4 Boolean Indexing
    3.5 nan
    3.6 infinity
    3.7 random
    3.8 Challenge: Love Distance
    3.9 Challenge: Professor Prick
    3.10 Challenge: Psycho Parent
  4. Common Operations
    4.1 where()
    4.2 Math Functions
    4.3 all() and any()
    4.4 concatenate()
    4.5 Stacking
    4.6 Sorting
    4.7 unique()
    4.8 Challenge: Movie Ratings
    4.9 Challenge: Big Fish
    4.10 Challenge: Taco Truck
  5. Advanced Array Stuff
    5.1 Advanced Array Indexing
    5.2 View vs Copy
    5.3 Challenge: Population Verification
    5.4 Challenge: Prime Locations
    5.5 Challenge: The Game of Doors
    5.6 Challenge: Peanut Butter
  6. Final Boss
    6.1 as_strided()
    6.2 einsum()
    6.3 Challenge: One-Hot-Encoding
    6.4 Challenge: Cumulative Rainfall
    6.5 Challenge: Table Tennis
    6.6 Challenge: Where’s Waldo
    6.7 Challenge: Outer Product

Additional Content

  1. Python Pandas For Your Grandpa
  2. Neural Networks For Your Dog
  3. Introduction To Google Colab