CODEWITHSUNDEEP
pythonstringfor-loop
barskyn
barskyn

Reputation: 383

Find the next iteration in loop python

I am trying to find out if given a string if 2 target characters follow one another. So essentially, I am trying to find if a character and its neighbor are target characters. How should I go about this? The following is what I have tried so far. 

target_list=["t","a","r","g","e","t"]

for char in some_string:
    if (char and some_string[some_string.index(char)+1]) in target_list:
        print ("correct")
    else:
        print ("incorrect")

Expected output:

  1. if some_string="heytr" == "correct"
  2. if some_string="hyt" == "incorrect"
  3. if some_string="heyt" == "incorrect"

Upvotes: 2

Views: 1777

Answers (6)

Inaganti venkatesh
Inaganti venkatesh

Reputation: 9

def judge(some_string):
for index in range(0,len(some_string)-1):
    if some_string[index] in target_list and some_string[index+1] in target_list:
        print("correct")
        break
else:
    print("incorrect")

judge("heytr") --correct
judge("hyt") -- incorrect
judge("heyt") --incorrect

For loop iterates on all character of the string checks if i and i+1 is present in target.if yes prints out correct. after all iterations of loop is over if no two character are found in target it comes to the else part of for loop and prints out incorrect.

Upvotes: -1

RoadRunner
RoadRunner

Reputation: 26335

You can also use any() and zip() for this:

target_list=["t","a","r","g","e","t"]

target_list = set(target_list)

some_strings = ["heytr", "hyt", "heyt"]

def match_strings(string, target_list):
    return any(x in target_list and y in target_list for x, y in zip(string, string[1:]))

for some_string in some_strings:
    if match_strings(some_string, target_list):
        print("correct")
    else:
        print("incorrect")

Which Outputs: 

correct
incorrect
incorrect

Logic of above code:

  • Converts target_list to a set, since set lookup is constant time. If you keep it as a list, then lookup time is linear.
  • Uses zip() to create pairs of the current element and the next element, and checks if both of these elements exist in target_list. Then checks if any() of the pairs exist, which returns True if any of the pairs exist, and False if none exist.
  • Then loop over all the strings in some_strings, and check the above for each one.

Upvotes: 0

xiaofeng.li
xiaofeng.li

Reputation: 8597

A regular expression solution.

import re

target_chars='target'

p = re.compile('[%s]{2}' % re.escape(target_chars))
m = p.search(some_string)
if m:
    print('correct')
else:
    print('incorrect')

Upvotes: 1

wim
wim

Reputation: 363616

from itertools import tee

def rolling_window(iterable, n=2):
    iterators = tee(iterable, n)
    for i, iterator in enumerate(iterators):
        for skip in range(i):
            next(iterator, None)
    return zip(*iterators)

def match(some_string, target, n=2):
    target = set(target)
    return any(target.issuperset(s) for s in rolling_window(some_string, n=n))

Upvotes: 1

user184868
user184868

Reputation: 183

Just use map:

    target_list=['t','a','r','g','e']

def toDict(list):
    mp  = {}
    for c in list:
        mp[c] = True
    return mp

d = toDict(target_list)

print("dict:" , d)    

def check(string, mp):
    count = 0
    for c in string:
        if(mp.get(c,False)):
            count = count+1
            if(count > 1):
                return True
        else:
            count = 0   
    return False


print("check:" , check("heytr", d))       
print("check:" , check("hyt", d))    
print("check:" , check("heyt", d))

Upvotes: 1

iBug
iBug

Reputation: 37327

Just go through the indices and process every pair of characters:

for i in range(len(some_string) - 1):
    if some_string[i] in target_list and some_string[i+1] in target_list:
        print ("correct")
        break

if i == len(some_string) - 1:
    print ("incorrect")

You can alternatively create a mapping and look for adjacent true positives:

m = [(char in target_list) for char in some_string]

for i in range(len(m) - 1):
    if m[i] and m[i+1]:
        print ("correct")
        break
if i == len(m) - 1:
    print ("incorrect")

Upvotes: 1

Related Questions