[M3devel] STL algorithms? sort/unique?
mika at async.caltech.edu
mika at async.caltech.edu
Fri Sep 28 10:04:48 CEST 2012
BTW I had the same experience when I first started using Modula-3.
It was painful to jump through all its hoops, coming from C, where you
can do whatever you want to whatever bits happen to be sloshing around
your machine. C++ from what I have seen mainly lets you do that to
more bits in fewer lines of code.
But after a while I really came to appreciate the value of things like the
language's telling me I'm using the wrong data structure instead of
just letting me use the same "nice, terse, efficient" syntax to write
a crappy program :-)
mika writes:
>You're using the wrong (abstract) data structure if you want sort and unique.
>
>A "sequence" is meant to be accessed sequentially...
>
>Not knowing precisely what you're doing it sounds like you might want a
>SortedTable... you can get unique on insert and access it in increasing
>or decreasing order.
>
> Mika
>
>Jay K writes:
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>> I have an IntSeq.T with a bunch of integers. =20
>> What is a good terse efficient idiom for sort and unique? =20
>>
>> In C++ I would say: vector<int> a=3B a.push_back(...)=3B =
>> a.push_back(...)=3B std::sort(a.begin()=2C a.end())=3B =
>> a.resize(std::unique(a.begin()=2C a.end()) - a.begin())=3B for (aut=
>>o i =3D a.begin()=3B i !=3D a.end()=3B ++i) {
>> do stuff with *i }=20
>> Nice=2C terse=2C efficient. In Modula-3? =20
>>
>>I know that unique is one of the easiest algorithms to manually write inlin=
>>e=2Cbut I shouldn't have to.
>>
>>(I'm really trying to stay in Modula-3 here=2C but it is definitely a strug=
>>gle. :( )
>>
>>Thank you=2C - Jay
>>
>> =
>>
>>--_d2a02ece-d492-410e-88fb-fb53737d7219_
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>><html>
>><head>
>><style><!--
>>.hmmessage P
>>{
>>margin:0px=3B
>>padding:0px
>>}
>>body.hmmessage
>>{
>>font-size: 12pt=3B
>>font-family:Calibri
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>><body class=3D'hmmessage'><div dir=3D'ltr'> =3B  =3B =3BI have =
>>an IntSeq.T with a bunch of integers. =3B  =3B =3B<br><div><spa=
>>n style=3D"font-size: 12pt=3B "> =3B  =3B</span><span style=3D"font=
>>-size: 12pt=3B "> =3B</span>What is a good terse efficient idiom for so=
>>rt and unique?<span style=3D"font-size: 12pt=3B "> =3B  =3B</span><=
>>span style=3D"font-size: 12pt=3B "> =3B</span></div><div><br></div><div=
>>><br></div><div> =3B  =3B In C++ I would say:<span style=3D"font-si=
>>ze: 12pt=3B "> =3B  =3B</span><span style=3D"font-size: 12pt=3B ">&=
>>nbsp=3B</span></div><div><span style=3D"font-size: 12pt=3B "> =3B  =
>>=3B</span><span style=3D"font-size: 12pt=3B "> =3B</span>vector<=3Bin=
>>t>=3B a=3B<span style=3D"font-size: 12pt=3B "> =3B  =3B</span><sp=
>>an style=3D"font-size: 12pt=3B "> =3B</span></div><div><span style=3D"f=
>>ont-size: 12pt=3B "> =3B  =3B</span><span style=3D"font-size: 12pt=
>>=3B "> =3B</span>a.push_back(...)=3B<span style=3D"font-size: 12pt=3B "=
>>> =3B  =3B</span><span style=3D"font-size: 12pt=3B "> =3B</span=
>>></div><div><div><span style=3D"font-size: 12pt=3B "> =3B  =3B</spa=
>>n><span style=3D"font-size: 12pt=3B "> =3B</span>a.push_back(...)=3B<sp=
>>an style=3D"font-size: 12pt=3B "> =3B  =3B</span><span style=3D"fon=
>>t-size: 12pt=3B "> =3B</span></div><div><span style=3D"font-size: 12pt=
>>=3B "> =3B  =3B</span><span style=3D"font-size: 12pt=3B "> =3B<=
>>/span>std::sort(a.begin()=2C a.end())=3B<span style=3D"font-size: 12pt=3B "=
>>> =3B  =3B</span><span style=3D"font-size: 12pt=3B "> =3B</span=
>>></div><div><span style=3D"font-size: 12pt=3B "> =3B  =3B</span><sp=
>>an style=3D"font-size: 12pt=3B "> =3B</span>a.resize(std::unique(a.begi=
>>n()=2C a.end()) - a.begin())=3B<span style=3D"font-size: 12pt=3B "> =3B=
>>  =3B</span><span style=3D"font-size: 12pt=3B "> =3B</span></div><d=
>>iv><span style=3D"font-size: 12pt=3B "> =3B  =3B for (auto i =3D a.=
>>begin()=3B i !=3D a.end()=3B ++i)</span></div><div><span style=3D"font-size=
>>: 12pt=3B "> =3B  =3B {<br> =3B  =3B  =3B do stuff with=
>> *i</span></div><div><span style=3D"font-size: 12pt=3B "> =3B  =3B =
>>}</span></div><div> =3B</div><div><br></div><div><span style=3D"font-si=
>>ze: 12pt=3B "> =3B  =3B</span><span style=3D"font-size: 12pt=3B ">&=
>>nbsp=3B</span>Nice=2C terse=2C efficient.<span style=3D"font-size: 12pt=3B =
>>"> =3B  =3B</span><span style=3D"font-size: 12pt=3B "> =3B</spa=
>>n></div><div><span style=3D"font-size: 12pt=3B "> =3B  =3B</span><s=
>>pan style=3D"font-size: 12pt=3B "> =3B</span>In Modula-3?<span style=3D=
>>"font-size: 12pt=3B "> =3B  =3B</span><span style=3D"font-size: 12p=
>>t=3B "> =3B</span></div><div><br></div><div><br></div><div>I know that =
>>unique is one of the easiest algorithms to manually write inline=2C</div><d=
>>iv>but I shouldn't have to.</div><div><br></div><div><br></div><div>(I'm re=
>>ally trying to stay in Modula-3 here=2C but it is definitely a struggle. :(=
>> )</div><div><br></div><div><br></div><div>Thank you=2C</div><div> =3B-=
>> Jay</div><br><br></div> </div></body>
>></html>=
>>
>>--_d2a02ece-d492-410e-88fb-fb53737d7219_--
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