Re: [9fans] rows to cols?

Re: [9fans] rows to cols?

[erik quanstrom]

> It's dog slow (actually, avl(2) is), but its effectively
> unbounded for the input dataset size.

i haven't found avl to be slow, so i was interested in
this.  after stripping out the tmp file and the
unnecessary runes, prof tells me this for a
2000x10000 array.  (normal runtime ~20s)

minooka; prof /mnt/term/usr/quanstro/8.out prof.116938
  %     Time     Calls  Name
50.0  115.833 486724015	_insertavl
12.5   28.961 466724015	cmp
11.9   27.586        1	main
11.4   26.465 466724015	balance
 3.9    9.080 168888891	Bgetc
 3.9    9.069 168888890	Bputc
[...]
 1.5    3.376 20000000	findsuccessor

okay, you're measuring that building an avl tree
takes n log(n)/log(2).  if it were not, i'd be worried!  note
also that the ratio of time(_insertavl)/time(findsuccessor)
= log(n)/log(2).  findsuccessor is the meat of walkavl.

in http://iwp9.org/papers/upasexp.pdf i talked about
a similar issue with hash tables.  if all you do is build
a fast-access structure, then they can be really slow.

- erik

Re: [9fans] rows to cols?

[Lyndon Nerenberg (VE6BBM/VE7TFX)]

> i haven't found avl to be slow, so i was interested in
> this.

It was slow in relation to other methods available.  That code wasn't
written to be fast.  It came out of a long ago Sunday afternoon
discussion I had with someone about data structures, from which we
ended up cobbling together a few different versions of transpose to
get some timings.  That was the only version that seems to have
survived, so that's the one you got ;-)

Re: [9fans] rows to cols?

[dave.l]

> It's the sort of thing I used to give as an exercise to students.

Wish I'd been in your class.

> Explicit looping looks so strenuous.

I know: I kept thinking "map ... join": too much perl.

> To make the tr|pr method more general, you can count columns first
> with

But that's multi-pass:-).

You could of course, use one pass of wc to count the words and lines,
then divide words by lines to get cols:-).

There are too many mad genius coders on this list.
Next: count the number of angels dancing on the head of a pin using an
acid function.

Can we talk about plan9 now, please?

D

Re: [9fans] rows to cols?

[Richard Miller]

> Wow.
> Excellent us of tools.

It's the sort of thing I used to give as an exercise to students.

> The smallest arbitrary-columns answer I could come up with was:
> awk '{if(m < NF)m=NF;for(i=1;i<=NF;i++)r[NR, i]=$i}END {for(i=1;i<=m;i+
> +){for(j=1;j<=NR;j++)printf "%s ", r[j,i];print ""}}' t

Explicit looping looks so strenuous.

To make the tr|pr method more general, you can count columns first with
	sed 1q | wc -b
or if you like
	awk '{print NF;exit}'

Counting rows is left as an exercise to the reader ...

Re: [9fans] rows to cols?

[Lyndon Nerenberg (VE6BBM/VE7TFX)]

> Is there an easy way to transpose the text so that rows become
> columns, and vice versa? Delimiter is space. Perhaps in AWK?

If Richard's trick won't work, grab contrib/lyndon/transpose.c.

It's dog slow (actually, avl(2) is), but its effectively
unbounded for the input dataset size.

--lyndon

P.S. Never underestimate the power of C.

Re: [9fans] rows to cols?

[dave.l]

Wow.
Excellent us of tools.

The smallest arbitrary-columns answer I could come up with was:
awk '{if(m < NF)m=NF;for(i=1;i<=NF;i++)r[NR, i]=$i}END {for(i=1;i<=m;i+
+){for(j=1;j<=NR;j++)printf "%s ", r[j,i];print ""}}' t

I'm sure there's an insane sed solution out there somewhere for very
small numbers of rows and columns.

D

On 13 Nov 2009, at 08:44, Richard Miller wrote:

>> Is there an easy way to transpose the text so that rows become
>> columns, and vice versa? Delimiter is space.
>
> If you know in advance the number of rows & colums, it's easy:
>
> term% cat t
> one two three four
> five six seven eight
> nine ten eleven twelve
> term%  tr -s ' ' '\xA' <t | pr -t -3 -l4 | tr -s ' ' ' '
> one five nine
> two six ten
> three seven eleven
> four eight twelve
>
>

Re: [9fans] rows to cols?

[Tharaneedharan Vilwanathan]

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hi,

i rustled up a small limbo program (attached) that does the trick.

hope this helps.

% cat num1.txt
one two three
four five six
seven eight nine
% ./trans num1.txt
     one      four     seven
     two      five     eight
   three       six      nine
% cat num2.txt
one two three four
five six seven
eight nine
ten
eleven twelve
thirteen fourteen fifteen
sixteen seventeen eighteen nineteen
% ./trans num2.txt
     one      five     eight       ten    eleven  thirteen   sixteen
     two       six      nine      ----    twelve  fourteen seventeen
   three     seven      ----      ----      ----   fifteen  eighteen
    four      ----      ----      ----      ----      ----  nineteen
%

thanks
dharani

On Fri, Nov 13, 2009 at 12:44 AM, Richard Miller <9fans@hamnavoe.com> wrote:
>
> > Is there an easy way to transpose the text so that rows become
> > columns, and vice versa? Delimiter is space.
>
> If you know in advance the number of rows & colums, it's easy:
>
> term% cat t
> one two three four
> five six seven eight
> nine ten eleven twelve
> term%  tr -s ' ' '\xA' <t | pr -t -3 -l4 | tr -s ' ' ' '
> one five nine
> two six ten
> three seven eleven
> four eight twelve
>
>

[-- Attachment #1.2: Type: text/html, Size: 3106 bytes --]

[-- Attachment #2: trans.b --]
[-- Type: application/octet-stream, Size: 1064 bytes --]

implement Trans;

include "sys.m";
	sys: Sys;

include "draw.m";
include "bufio.m";

MaxList : con 500;

Trans: module
{
	init:	fn(nil: ref Draw->Context, args: list of string);
};

init(nil: ref Draw->Context, args: list of string)
{
	sys = load Sys Sys->PATH;

	if (len args != 2) {
		sys->print("Error! File too big\n");
		exit;
	}

	File := hd tl args;
     	bufio := load Bufio Bufio->PATH;
	Iobuf : import bufio;
	lc := bufio->open(File, bufio->OREAD);

	MaxRow := 0;
	MaxCol := 0;
	List := array [500] of list of string;
	i := 0;
	while (1) {
     		text := lc.gets('\n');
		if (text == nil) break;
		Count := 0;
		(Count, List[i++]) = sys->tokenize(text, " \n");
		if (MaxCol < Count) {
			MaxCol = Count;
		}
		MaxRow++;
		if (MaxRow >= MaxList) {
			sys->print("Error! File too big\n");
			exit;
		}
	}

	for (i = 0; i < MaxCol; i++) {
		for (j := 0; j < MaxRow; j++) {
			#if (List[j] == nil) continue;
			if (List[j] == nil) {sys->print("%9s ", "----"); continue;}
			sys->print("%9s ", hd List[j]); List[j] = tl List[j];
		}
		sys->print("\n");
	}
}

Re: [9fans] rows to cols?

[Richard Miller]

> Is there an easy way to transpose the text so that rows become
> columns, and vice versa? Delimiter is space.

If you know in advance the number of rows & colums, it's easy:

term% cat t
one two three four
five six seven eight
nine ten eleven twelve
term%  tr -s ' ' '\xA' <t | pr -t -3 -l4 | tr -s ' ' ' '
one five nine
two six ten
three seven eleven
four eight twelve

[9fans] rows to cols?

[Peter A. Cejchan]

Hi, folks!

Is there an easy way to transpose the text so that rows become
columns, and vice versa? Delimiter is space. Perhaps in AWK?

Thanks,

=============================
Petr A. Cejchan
<cej@gli.cas.cz, tyapca7@gmail.com>
http://home.gli.cas.cz/cej/www/
http://www.facebook.com/cejchan
work: +420-233 087 237
home/SMS: +420-720 121 721
ICQ: 583000501
=============================