Python: Change range location with loop

Question

I would like my program to print every other letter in the string "welcome". like:

e
c
m

Here is the code I have so far:

stringVar = "welcome"
countInt = 7

count = 0
oneVar = 1
twoVar = 2

showVar = stringVar[oneVar:twoVar]

for count in range(countInt):
count = count + 1
oneVar = oneVar + count
twoVar = twoVar + count

print(showVar)

Though it only shows the 2nd letter "e". How can I get the variables oneVar and twoVar to update so that the range changes for the duration of the loop?

score 4 · Answer 1 · edited May 23 '17 at 11:49

4

There is a built in notation for this, called "slicing":

>>> stringVar = "welcome"
>>> print(stringVar[::2])
wloe
>>> print(stringVar[1::2])
ecm

stringVar is iterable like a list, so the notation means [start : end : step]. Leaving any one of those blank implicitly assumes from [0 : len(stringVar) : 1]. For more detail, read the linked post.

edited May 23 '17 at 11:49

Community

1
1

answered Feb 14 '14 at 07:43

mhlester

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James Sapam · Answer 2 · 2014-02-14T08:13:39.403

0

Why its not working in your snipet:

Even though you increase oneVar and twoVar inside the loop, there is no change in the showVar as showVar is string which is immutable type, and its printing stringVar[1:2] which is e the 2nd index of welcome:

Just to fix your snippet: You can just try like this;

stringVar = "welcome"
countInt = 7

for count in range(1,countInt,2):
   print count, stringVar[count]

Output:

e
c
m

edited Feb 14 '14 at 08:13

answered Feb 14 '14 at 07:49

James Sapam

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He doesn't want every second character :) – thefourtheye Feb 14 '14 at 07:58
did i put something wrong or ? i think i was explaining why he got only 2nd character. – James Sapam Feb 14 '14 at 08:07
He expects only `e c m` – thefourtheye Feb 14 '14 at 08:08

score 0 · Answer 3 · answered Feb 14 '14 at 07:51

Another more complex way of the doing the same would be

string_var = "welcome"

for index, character in enumerate(string_var, start=1):  # 'enumerate' provides us with an index for the string and 'start' allows us to modify the starting index.
    if index%2 == 0:
        print character

Python: Change range location with loop

3 Answers3