Python for Data Science for Dummies contains an error in the example that appears on the top half of page 124. In the first of the two grey boxes, the code computes the results of four print statements. The bottom-most print statement, print x[1:2, 1:2], is supposed to compute a result based on rows 1 and 2 of columns 1 and 2, and the bottom grey box seems to confirm that interpretation by the showing the result as [[[14 15 16] [17 18 19]] [[24 25 26] [27 28 29]]]. However, the answer provided for this example in the downloadable source code is [[[14 15 16]]], which doesn’t agree with that in the text.
The good news is that the downloadable source contains the correct code. The error appears only in the book. The last print statement in the book is wrong. Here is the correct code (with output) for this example:
x = np.array([[[1, 2, 3], [4, 5, 6], [7, 8, 9],],
[[11,12,13], [14,15,16], [17,18,19],],
[[21,22,23], [24,25,26], [27,28,29]]])
print x[1,1]
print x[:,1,1]
print x[1,:,1]
print
print x[1:3, 1:3]
[14 15 16]
[ 5 15 25]
[12 15 18]
[[[14 15 16]
[17 18 19]]
[[24 25 26]
[27 28 29]]]Please let me know if you have any questions about this example at [email protected]. I’m sorry about the error that appears in the book and appreciate the readers who have pointed it out.