CODEWITHSUNDEEP
pythonpython-3.x
DwightD
DwightD

Reputation: 157

Python 3.6: Moving around words within a string

I know that this function moves around characters in a string, as such:

def swapping(a, b, c):
    x = list(a)
    x[b], x[c] = x[c], x[b]
    return ''.join(x)

Which allows me to do this:

swapping('abcde', 1, 3)
'adcbe'
swapping('abcde', 0, 1)
'bacde'

But how can I get it to do something like this, so I'm not just moving around letters? This is what I want to accomplish:

swapping("Boys and girls left the school.", "boys", "girls")
swapping("Boys and girls left the school.", "GIRLS", "bOYS")
should both have an output: "GIRLS and BOYS left the school." 
# Basically swapping the words that are typed out after writing down a string

Upvotes: 2

Views: 696

Answers (4)

Yuvraj Jaiswal
Yuvraj Jaiswal

Reputation: 1723

You can do something like this:

def swap(word_string, word1, word2):
    words = word_string.split()
    try:
        idx1 = words.index(word1)
        idx2 = words.index(word2)
        words[idx1], words[idx2] = words[idx2],words[idx1]
    except ValueError:
        pass
    return ' '.join(words)

Upvotes: 3

Jean-François Fabre
Jean-François Fabre

Reputation: 140196

with regular expressions and a replacement function (could be done with lambda and a double ternary but that's not really readable)

Matches all the words (\w+) and compares against both words (case-insensitive). If found, return the "opposite" word.

import re

def swapping(a,b,c):
    def matchfunc(m):
        g = m.group(1).lower()
        if g == c.lower():
            return b.upper()
        elif g == b.lower():
            return c.upper()
        else:
            return m.group(1)

    return re.sub("(\w+)",matchfunc,a)

print(swapping("Boys and girls left the school.", "boys", "girls"))
print(swapping("Boys and girls left the school.", "GIRLS", "bOYS"))

both print: GIRLS and BOYS left the school.

Upvotes: 2

Olivier Melançon
Olivier Melançon

Reputation: 22314

You want to do two separate things here: swapping and changing character case.

The former has been addressed in other answers.

The later can be done by searching words in a case insensitive manner, but replacing with the input words, keeping cases.

def swapping(word_string, word1, word2):
    # Get list of lowercase words
    lower_words = word_string.lower().split()

    try:
        # Get case insensitive index of words
        idx1 = lower_words.index(word1.lower())
        idx2 = lower_words.index(word2.lower())
    except ValueError:
        # Return the same string if a word was not found
        return word_string

    # Replace words with the input words, keeping case
    words = word_string.split()
    words[idx1], words[idx2] = word2, word1

    return ' '.join(words)

swapping("Boys and girls left the school.", "GIRLS", "BOYS")
# Output: 'GIRLS and BOYS left the school.'

Upvotes: 0

Keshav Garg
Keshav Garg

Reputation: 379

Use split function to get a list of words separated by whitespaces 

def swapping(a, b, c):
x = a.split(" ")
x[b], x[c] = x[c], x[b]
return ' '.join(x)

If you want to pass strings as parameters use .index() to get index of the strings that you want to swap.

def swapping(a, b, c):
x = a.split(" ")
index_1 = x.index(b)
index_2 = x.index(c)
x[index_2], x[index_1] = x[index_1], x[index_2]
return ' '.join(x)

Upvotes: 2

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