How to increment index in Python loop

Question

I am wanting to loop through a string and capture 2 items each time while also incrementing through the index of the iterable. So I want to slice 2 items but increase the index by 1 every time through the loop. How can I do this?

my_string = ‘teststring’

desired output =
te
es
st
ts
st
tr
ri
in
ng

I have tried the following to slice the two items, but can’t figure out the best way to iterate thought the index

str1 = 'teststring'
i=0
while i<10: 
    i +=1
    str2=str1[0:2]
    print(str2)

Asked By: Soupy

||

Source

Answer 1

Here is a possible solution (s is your string):

for j in range(len(s) - 1):
    print(s[j:j + 2])

Another one:

for c1, c2 in zip(s[:-1], s[1:]):
    print(c1 + c2)

Answered By: Riccardo Bucco

Answer 2

str1 = 'teststring'
result = []
for i in range(len(str1) - 1):
    result.append(str1[i:i + 2])

print(result)

output

['te', 'es', 'st', 'ts', 'st', 'tr', 'ri', 'in', 'ng']

Answered By: Jossef Harush Kadouri

Answer 3

Since you are trying to move both the start and end point of the slice with each iteration, you want to use the index+length of slice for the end point.

You should iterate after the slice is done. Here is the answer with minimal changes to your code:

str1 = 'teststring'
i=0
while i<=len(str1)-2: 
    str2=str1[i:i+2]
    i += 1
    print(str2)

Answered By: Bartosz Raubo

Answer 4

I would use a for loop instead of a while loop, like this:

def strangeSlice(string):
    out = ""
    for i in range(len(string)-1):
        out += string[i:i+2]
        if i != len(string)-2:
            out += " "
    print(out)
    return out
def main():
    strangeSlice("teststring")
main() #you need to call the main function to run

Answered By: kenntnisse

Answer 5

By using list comprehension you can do this in a one-liner

s = 'teststring'

r = ' '.join([s[i:i+2] for i in range(len(s)-1)])

print(r)

Answered By: Daniel F

Answer 6

An ITERABLE is:

anything that can be looped over (i.e. you can loop over a string or file) or
anything that can appear on the right-side of a for-loop: for x in iterable: … or
anything you can call with iter() that will return an ITERATOR: iter(obj) or
an object that defines iter that returns a fresh ITERATOR, or it may have a getitem method suitable for indexed lookup.

Answered By: Alex Dorwans

Answer 7

from linked_list import LinkedList, LinkedListIterator

class TVChannel:

def _init_(self):
    self.full = LinkedList()
    self.favs = LinkedList()
    self.channel_tr = LinkedList()
    

def add_channel(self, number, name, favorite):
    mov = {
        "number": number,
        "name": name
    }
    self.full.insert_back(mov)

    if favorite:
        self.favs.insert_front(name)
    if self.channel_tr is None:
        self.channel_tr = LinkedListIterator(self.full)
    

def current_channel(self):
    return self.channel_tr.current_value()['number']

def up_channel(self):
    self.channel_tr = self.channel_tr.next()

def all_channels(self):
    return self.full.get_iterator()

def favorite_channels(self):
    return self.favs.get_iterator()

Answered By: alex a

How to increment index in Python loop

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