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Samoro Palacios
2,430 PointsConfused on negative step
colors = ['red', 'orange', 'yellow', 'green', 'blue', 'indigo', 'violet']
colors_partial = colors[3:6:-1]
print(colors_partial)
When I entered this the output was an empty list. From what I understand a negative step is just supposed to count from the end of the list as opposed to the beginning. So why wouldn't this work?
1 Answer
Joseph Yhu
PHP Development Techdegree Graduate 48,637 Pointscolors_partial = colors[3:6:-1]
You are telling the program to go from index 3 to the end backwards. The correct way is:
colors = ['red', 'orange', 'yellow', 'green', 'blue', 'indigo', 'violet']
colors_partial = colors[6:3:-1]
print(colors_partial)
Since index 6 is the end you can also do:
colors = ['red', 'orange', 'yellow', 'green', 'blue', 'indigo', 'violet']
colors_partial = colors[-1:3:-1]
print(colors_partial)
You can leave out the first part entirely too:
colors = ['red', 'orange', 'yellow', 'green', 'blue', 'indigo', 'violet']
colors_partial = colors[:3:-1]
print(colors_partial)
All three will print ['violet', 'indigo', 'blue'].
Samoro Palacios
2,430 PointsSamoro Palacios
2,430 PointsSo I think I understand the issue now. Please correct me if I'm wrong. The negative step doesn't change the index number of the list. So when I told it to count backwards from the index 3. Index 6 was no longer in that range so it output was empty? Thank you!