#!/usr/bin/python
# 1.11. Naming a Slice
# Problem: Your program has become an unreadable mess of
# hardcoded slice indices and you want to clean it up.
###### 0123456789012345678901234567890123456789012345678901234567890'
record = '....................100 .......513.25 ..........'
cost = int(record[20:32]) * float(record[40:48])
print (cost)
# name the slices
SHARES = slice(20,32)
PRICE = slice(40,48)
cost = int(record[SHARES]) * float(record[PRICE])
print (cost)
items = [0, 1, 2, 3, 4, 5, 6]
a = slice(2, 4)
print (items[2:4])
print (items[a])
items[a] = [10,11]
print (items)
del items[a]
print (items)
a = slice(10, 50, 2)
print (a.start, a.stop, a.step)
s = 'HelloWorld'
indice = a.indices(len(s))
print (indice)
for i in range(*a.indices(len(s))):
print(s[i])
This is the example in Chapter 1.11 of the Python Cookbook.
print (indices)
This should give me (5,10,2) but it gives me (10,10,2). Then the following for-loop did not print anything.
Why the results shown of my code is not like in the book?
This is actually an error in the book. If you check the errata and scroll down to page 19, there is this description:
This example "a.indices(len(s))" leads to output that differs from the output as printed in the book, assuming the slice a is the slice a as shown in the example just above. It would work in the way shown, if a were slice(5, 50, 2) or so. Or am I wrong?
Note from the Author or Editor: Change example mid-page to this:
>>> a = slice(5, 50, 2) >>> a.start 5 >>> a.stop 50 >>> a.step 2 >>>Problematic example at bottom should then work.