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POIdentify substrings and return responses based on order of substrings in Python
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  1. POIdentify substrings and return responses based on order of substrings in Python
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    copied!<p>I am a beginner in Python, I am teaching myself off of Google Code University online. One of the exercises in string manipulation is as follows:</p> <pre><code># E. not_bad # Given a string, find the first appearance of the # substring 'not' and 'bad'. If the 'bad' follows # the 'not', replace the whole 'not'...'bad' substring # with 'good'. # Return the resulting string. # So 'This dinner is not that bad!' yields: # This dinner is good! def not_bad(s): # +++your code here+++ return </code></pre> <p>I'm stuck. I know it could be put into a list using <code>ls = s.split(' ')</code> and then sorted with various elements removed, but I think that is probably just creating extra work for myself. The lesson hasn't covered RegEx yet so the solution doesn't involve re. Help?</p> <p>Here's what I tried, but it doesn't quite give the output correctly in all cases:</p> <pre><code>def not_bad(s): if s.find('not') != -1: notindex = s.find('not') if s.find('bad') != -1: badindex = s.find('bad') + 3 if notindex &gt; badindex: removetext = s[notindex:badindex] ns = s.replace(removetext, 'good') else: ns = s else: ns = s else: ns = s return ns </code></pre> <p>Here is the output, it worked in 1/4 of the test cases:</p> <pre><code>not_bad X got: 'This movie is not so bad' expected: 'This movie is good' X got: 'This dinner is not that bad!' expected: 'This dinner is good!' OK got: 'This tea is not hot' expected: 'This tea is not hot' X got: "goodIgoodtgood'goodsgood goodbgoodagooddgood goodygoodegoodtgood goodngoodogoodtgood" expected: "It's bad yet not" </code></pre> <p>Test Cases:</p> <pre><code>print 'not_bad' test(not_bad('This movie is not so bad'), 'This movie is good') test(not_bad('This dinner is not that bad!'), 'This dinner is good!') test(not_bad('This tea is not hot'), 'This tea is not hot') test(not_bad("It's bad yet not"), "It's bad yet not") </code></pre> <p><strong>UPDATE:</strong> This code solved the problem:</p> <pre><code>def not_bad(s): notindex = s.find('not') if notindex != -1: if s.find('bad') != -1: badindex = s.find('bad') + 3 if notindex &lt; badindex: removetext = s[notindex:badindex] return s.replace(removetext, 'good') return s </code></pre> <p>Thanks everyone for helping me discover the solution (and not just giving me the answer)! I appreciate it!</p>
 

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