Re: [Gnuplot-info] string variables and iteration (gnuplot 4.6)

[Leo B. <l_b...@us...>]

>   From: Leo Butler <l_b...@us...>
>   CC: <gnu...@li...>
>
>
>   >   Date: Thu, 19 Sep 2013 04:51:31 -0700
>   >   From: "atoms.h" <tho...@gm...>
>   >   Content-Type: text/plain; charset="us-ascii"
>   >
>   >   Hi,
>   >
>   >   I'm trying to make use of the iteration feature, so far unsuccessfully. I
>   >   want to plot files in different directories with the same file name. All in
>   >   one pdf documents. The way I construct my paths is by means of string
>   >   variables:
>   >
>   >   $ basefolder = '../data/scalePr/'
>   >   $ folder1 = '0.90'
>   >   $ folder2 = '0.95'
>   >   $ folder3 = '0.97'
>   >   $ folder4 = '1.00'
>   >   $ file1 = basefolder.folder1."/".filename.".dat"
>   >   $ file2 = basefolder.folder2."/".filename.".dat"
>   >   $ file3 = basefolder.folder3."/".filename.".dat"
>   >   $ file4 = basefolder.folder4."/".filename.".dat"
>   >
>   >   I haven't figured out a way to iterate through variable names like
>   >
>   >   $ file(n) = basefolder.folder.sprintf("%d",n)."/".filename.".dat"
>   >
>   >   (which obviously doesn't work) to be able to do multiple plots in one
>   >   command:
>   >
>   >   $ do for [i=1:4]{
>   >   $     splot file(i)
>   >   $ }
>   >
>   >   If anyone has an idea how to iterate variable names it would be most
>   >   appreciated!
>
>   It is probably best to use strings with separators to implement a type
>   of read-only string array. Here is one such effort
>
>   gnuplot> directory="/home/user"
>   gnuplot> files="a0 a1 a2 a3 "
>   gnuplot> sep=" "
>   gnuplot> c=strstrt(files,sep);
>   gnuplot>
>   gnuplot> while (c) { w=sprintf("%s/%s",directory,files[0:c-1]);
>   more> print w;
>   more> files=files[c+1:*]
>   more> c=strstrt(files,sep);
>   more> }
>   /home/user/a0
>   /home/user/a1
>   /home/user/a2
>   /home/user/a3
>
>   With a bit more work you can make a custom iterator:
>
>   gnuplot> files="a0 a1 a2 a3 a4 a5 a6 "
>   gnuplot> iterate_over_(string,sep,cmd,s,c)=(c == 0 ? s :\
>   >iterate_over_(string[c+1:*],sep,cmd,s . (c == -1 ? "" : sprintf(cmd,string[0:with_iterate_over_c-1])), strstrt(string[c+1:*],sep)));

That should have been:

iterate_over_(string,sep,cmd,s,c)=(c == 0 ? s :\
iterate_over_(string[c+1:*],sep,cmd,s . (c == -1 ? "" : sprintf(cmd,string[0:c-1])), strstrt(string[c+1:*],sep)));

I made a mistake copying from my work buffer, I guess.

To explain: iterate_over_ is a tail-recursive function that
recursively assembles a command string s, using the sprintf prototype
cmd, and the input string string which is separated by sep.

>   gnuplot> iterate_over(string,sep,cmd)=iterate_over_(string,sep,cmd,"",-1);

You can eval the output of iterate_over, or you could define a 3rd
function that does that for you.

>   gnuplot>
>   gnuplot> print iterate_over(files,sep,"file='%s'; splot directory .'/'. file;\n")
>   file='a0'; splot directory .'/'. file;
>   file='a1'; splot directory .'/'. file;
>   file='a2'; splot directory .'/'. file;
>   file='a3'; splot directory .'/'. file;
>   file='a4'; splot directory .'/'. file;
>   file='a5'; splot directory .'/'. file;
>   file='a6'; splot directory .'/'. file;

Leo