Re: List -> select method

Jacob Peck <[email protected]> Thu, 25 Oct 2012 08:23:02 -0400
Newsgroups gmane.comp.lang.io
Message-ID <[email protected]>
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 From Io:

Io> List getSlot("select")
==> # /home/peckj/repos/io/libs/iovm/io/A0_List.io:80
method(
     call delegateToMethod(self clone, "selectInPlace")
)
Io> List getSlot("selectInPlace")
==> # /home/peckj/repos/io/libs/iovm/io/A0_List.io:31
method(
     context := Object clone prependProto(call sender)

     if(call sender hasLocalSlot("self"),
         context self := call sender self
     )

     offset := 0
     argCount := call argCount

     if(argCount == 0, Exception raise("missing argument"))
     if(argCount == 1) then(
         body := call argAt(0)
         size repeat(idx,
             if(at(idx - offset) doMessage(body, context) not,
                 removeAt(idx - offset)
                 offset = offset + 1
             )
         )
     ) elseif(argCount == 2) then(
         eName := call argAt(0) name
         body := call argAt(1)
         size repeat(idx,
             context setSlot(eName, at(idx - offset))
             if(context doMessage(body) not,
                 removeAt(idx - offset)
                 offset = offset + 1
             )
         )
     ) else(
         iName := call argAt(0) name
         eName := call argAt(1) name
         body := call argAt(2)

         size repeat(idx,
             context setSlot(iName, idx)
             context setSlot(eName, at(idx - offset))
             if(context doMessage(body) not,
                 removeAt(idx - offset)
                 offset = offset + 1
             )
         )
     )
     self
)
Io> List getSlot("foreach")
==> List_foreach()

So, foreach is implemented in C (usually faster), and select is 
implemented in Io.  The short form (1 arg) of select is equivalent to 
the following code:

List mySelect := method(filter,
     context := Object clone prependProto(call sender)

     if(call sender hasLocalSlot("self"),
         context self := call sender self
     )

     offset := 0
         size repeat(idx,
             if(at(idx - offset) doMessage(filter, context) not,
                 removeAt(idx - offset)
                 offset = offset + 1
             )
         )
     )
)

I'd say that foreach could be faster, but YMMV.

You could benchmark this...

Io> someNums := list(20, 30, 27, 37, 21, 22)
==> list(20, 30, 27, 37, 21, 22)
Io> Date secondsToRun(someNums select(isOdd))
==> 0.002304
Io> Date secondsToRun(out := list; someNums foreach(x, if(x isOdd, out 
append(x))); out)
==> 0.000535

Looks like foreach is about 4.5 times faster, but takes more code.  This 
was done on my raspberry pi, so times will probably be much faster on a 
desktop.

You could redefine select so that it uses foreach internally, if you want.

-->Jake

On 10/24/2012 9:09 PM, Duke Normandin wrote:
>
>
> @Steve
> @Jake
>
> Thank you, gentlemen!!
>
> The fastest and "cheapest" option has got my vote. :D
>
> BTW, is *foreach* as cheap and as fast as *select*?
>
> -- 
> Duke
> “Tolerance becomes a crime when applied to evil.”― Thomas Mann
>
> 


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      <p>
  
  
    <div class="moz-cite-prefix">From Io:<br>
      <br>
      <tt>Io&gt; List getSlot("select")</tt><tt><br>
      </tt><tt>==&gt; # /home/peckj/repos/io/libs/iovm/io/A0_List.io:80</tt><tt><br>
      </tt><tt>method(</tt><tt><br>
      </tt><tt>    call delegateToMethod(self clone, "selectInPlace")</tt><tt><br>
      </tt><tt>)</tt><tt><br>
      </tt><tt>Io&gt; List getSlot("selectInPlace")</tt><tt><br>
      </tt><tt>==&gt; # /home/peckj/repos/io/libs/iovm/io/A0_List.io:31</tt><tt><br>
      </tt><tt>method(</tt><tt><br>
      </tt><tt>    context := Object clone prependProto(call sender)</tt><tt><br>
      </tt><tt><br>
      </tt><tt>    if(call sender hasLocalSlot("self"),</tt><tt><br>
      </tt><tt>        context self := call sender self</tt><tt><br>
      </tt><tt>    )</tt><tt><br>
      </tt><tt><br>
      </tt><tt>    offset := 0</tt><tt><br>
      </tt><tt>    argCount := call argCount</tt><tt><br>
      </tt><tt><br>
      </tt><tt>    if(argCount == 0, Exception raise("missing
        argument"))</tt><tt><br>
      </tt><tt>    if(argCount == 1) then(</tt><tt><br>
      </tt><tt>        body := call argAt(0)</tt><tt><br>
      </tt><tt>        size repeat(idx,</tt><tt><br>
      </tt><tt>            if(at(idx - offset) doMessage(body, context)
        not,</tt><tt><br>
      </tt><tt>                removeAt(idx - offset)</tt><tt><br>
      </tt><tt>                offset = offset + 1</tt><tt><br>
      </tt><tt>            )</tt><tt><br>
      </tt><tt>        )</tt><tt><br>
      </tt><tt>    ) elseif(argCount == 2) then(</tt><tt><br>
      </tt><tt>        eName := call argAt(0) name</tt><tt><br>
      </tt><tt>        body := call argAt(1)</tt><tt><br>
      </tt><tt>        size repeat(idx,</tt><tt><br>
      </tt><tt>            context setSlot(eName, at(idx - offset))</tt><tt><br>
      </tt><tt>            if(context doMessage(body) not,</tt><tt><br>
      </tt><tt>                removeAt(idx - offset)</tt><tt><br>
      </tt><tt>                offset = offset + 1</tt><tt><br>
      </tt><tt>            )</tt><tt><br>
      </tt><tt>        )</tt><tt><br>
      </tt><tt>    ) else(</tt><tt><br>
      </tt><tt>        iName := call argAt(0) name</tt><tt><br>
      </tt><tt>        eName := call argAt(1) name</tt><tt><br>
      </tt><tt>        body := call argAt(2)</tt><tt><br>
      </tt><tt><br>
      </tt><tt>        size repeat(idx,</tt><tt><br>
      </tt><tt>            context setSlot(iName, idx)</tt><tt><br>
      </tt><tt>            context setSlot(eName, at(idx - offset))</tt><tt><br>
      </tt><tt>            if(context doMessage(body) not,</tt><tt><br>
      </tt><tt>                removeAt(idx - offset)</tt><tt><br>
      </tt><tt>                offset = offset + 1</tt><tt><br>
      </tt><tt>            )</tt><tt><br>
      </tt><tt>        )</tt><tt><br>
      </tt><tt>    )</tt><tt><br>
      </tt><tt>    self</tt><tt><br>
      </tt><tt>)</tt><tt><br>
      </tt><tt>Io&gt; List getSlot("foreach")</tt><tt><br>
      </tt><tt>==&gt; List_foreach()</tt><br>
      <br>
      So, foreach is implemented in C (usually faster), and select is
      implemented in Io.  The short form (1 arg) of select is equivalent
      to the following code:<br>
      <br>
      <tt>List mySelect := method(</tt><tt>filter</tt><tt>,</tt><tt><br>
      </tt><tt>    context := Object clone prependProto(call sender)</tt><tt><br>
      </tt>
      <tt><br>
      </tt><tt>
      </tt><tt>    if(call sender hasLocalSlot("self"),</tt><tt><br>
      </tt><tt>
      </tt><tt>        context self := call sender self</tt><tt><br>
      </tt><tt>
      </tt><tt>    )</tt><tt><br>
      </tt>
      <tt><br>
      </tt><tt>
      </tt><tt>    offset := 0</tt><tt><br>
      </tt><tt>
      </tt><tt>        size repeat(idx,</tt><tt><br>
      </tt><tt>
      </tt><tt>            if(at(idx - offset) doMessage(filter,
        context) not,</tt><tt><br>
      </tt><tt>
      </tt><tt>                removeAt(idx - offset)</tt><tt><br>
      </tt><tt>
      </tt><tt>                offset = offset + 1</tt><tt><br>
      </tt><tt>
      </tt><tt>            )</tt><tt><br>
      </tt><tt>
      </tt><tt>        )</tt><tt><br>
      </tt><tt>
      </tt><tt>    )<br>
        )<br>
      </tt><br>
      I'd say that foreach could be faster, but YMMV.<br>
      <br>
      You could benchmark this...<br>
      <br>
      Io&gt; someNums := list(20, 30, 27, 37, 21, 22)<br>
      ==&gt; list(20, 30, 27, 37, 21, 22)<br>
      Io&gt; Date secondsToRun(someNums select(isOdd))<br>
      ==&gt; 0.002304<br>
      Io&gt; Date secondsToRun(out := list; someNums foreach(x, if(x
      isOdd, out append(x))); out)<br>
      ==&gt; 0.000535<br>
      <br>
      Looks like foreach is about 4.5 times faster, but takes more
      code.  This was done on my raspberry pi, so times will probably be
      much faster on a desktop.<br>
      <br>
      You could redefine select so that it uses foreach internally, if
      you want.<br>
      <br>
      --&gt;Jake<br>
      <br>
      On 10/24/2012 9:09 PM, Duke Normandin wrote:<br>
    </div>
    <blockquote cite="mid:[email protected]" type="cite">
      <span> </span>
      
          <div id="ygrp-text">
            <p><br>
              @Steve<br>
              @Jake<br>
              <br>
              Thank you, gentlemen!!<br>
              <br>
              The fastest and "cheapest" option has got my vote. :D<br>
              <br>
              BTW, is *foreach* as cheap and as fast as *select*?<br>
              <br>
              -- <br>
              Duke<br>
              “Tolerance becomes a crime when applied to evil.”― Thomas
              Mann<br>
            </p>
          </div>
          
      
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