11.7. EXERCISES 199
(a)s1 + s2
(b)3 * s1 + 2 * s2
(c)s1[1]
(d)s1[1:3]
(e)s1 + s2[-1]
- Giventhesameinitialstatementsasinthepreviousproblem,showthevaluesofs1ands2after
executingeachofthefollowingstatements.Treateachpartindependently(i.e.,assumethats1ands2
startwiththeiroriginalvalueseachtime).
(a)s1.remove(2)
(b)s1.sort().reverse()
(c)s1.append([s2.index(’b’)])
(d)s2.pop(s1.pop(2))
(e)s2.insert(s1[0],’d’)
- Modifythestatisticspackagefromthechaptersothatclientprogramshave moreflexibilityincom-
putingthemeanand/orstandarddeviation. Specifically, redesignthelibrarytohave thefollowing
functions:
mean(nums)Returnsthemeanofnumbersinnums.
stdDev(nums)Returnsthestandarddeviationofnums.
meanStdDev(nums)Returnsboththemeanandstandarddeviationofnums.
- Mostlanguagesdonothave theflexiblebuilt-inlist(array)operationsthatPythonhas.Writeanalgo-
rithmforeachofthefollowingPythonoperationsandtestyouralgorithmbywritingit upina suitable
function.Forexample,asa function,reverse(myList)shoulddothesameasmyList.reverse().
Obviously, youarenotallowedtousethecorrespondingPythonmethodtoimplementyourfunction.
(a)count(myList, x)(likemyList.count(x))
(b)isin(myList, x)(likex in myList))
(c)index(myList, x)(likemyList.index(x))
(d)reverse(myList)(likemyList.reverse())
(e)sort(myList)(likemyList.sort())
- Writeandtesta functionshuffle(myList)thatscramblesa listintoa randomorder, like shuffling
a deckofcards.
- TheSieve ofEratosthenesis anelegantalgorithmforfindingalloftheprimenumbersuptosomelimit
n. Thebasicideais tofirstcreatea listofnumbersfrom2 ton. Thefirstnumberis removedfromthe
list,andannouncedasa primenumber, andallmultiplesofthisnumberuptonareremovedfromthe
list.Thisprocesscontinuesuntilthelistis empty.
Forexample,if wewishedtofindalltheprimesupto10,thelistwouldoriginallycontain2,3,4,5,
6,7,8,9,10.The2 is removedandannouncedtobeprime.Then4,6,8 and 10 areremoved,since
they aremultiplesof2. Thatleaves3,5,7,9. Repeatingtheprocess,3 is announcedasprimeand
removed,and9 is removedbecauseit is a multipleof3.Thatleaves5 and7.Thealgorithmcontinues
byannouncingthat5 is primeandremovingit fromthelist.Finally, 7 is announcedandremoved,and
we’redone.
Writea programthatpromptsa userfornandthenusesthesieve algorithmtofindalltheprimesless
thanorequalton.
- CreateandtestaSetclassto representa classicalset.Yoursetsshouldsupportthefollowingmethods:
