Re: [Gnuplot-info] Fwd: How to realize a single plot in a double loop?

[ivana r. <iva...@mf...>]

Hi Ethan,

>> I can disable all syscalls on startup at all. Otherwise I need to
>> check if there are commands such 'rm -rf /', 'chmod -R a+r ~/.ssh',

> This idea has been raised before.
> The major problem I see with it is that gnuplot gains a lot of power from
> being able to filter input and output through pipes.

yes, I know. Pipes are nice and useful, but safe-check of other-hand
scripts quite annoying. Maybe it would helpful widespread if there are
strict simple rules for pipes and syscalls which can be demanded
irrevocably at startup via init-file, as:

- exact list of allowed commands including full path (e.g. /bin/grep,
/bin/cat) with possibility to define aliases for them (e.g.,
grep=/bin/grep)
- do not read or write and access files and directories (except
executing the allowed commands) outside the current directory tree at
startup.
- namely allow file extensions for files that can be (over)written.
- allow or not creating new subdirs.
- define permissions for new files and dirs.

>> probably continue development. Currently, on my wish-list there is (1)
>> a possibility to index arrays by letters OR get ascii code of chars,
>
> extension before considering it further.  Do you have an example
> application for which using a character as an array index is a  big win?

If I proceed letter-indexed files inside loops, then there are several
ways how to access filename-related variables.

I'd like, e.g., to fit files Data_<letter>.dat in one loop and used
the fitted values in another loop.

-------------------------------
1, eval, no arrays, so a "classic" way:
``
# filename format: Data_<letter>.dat
ind(filename) = filename[6:6]

# declare function myvar(x) that decodes myvarX
cls=' myvar(x)=('
do for [ i = 1 : 26 ] { cls = sprintf("%s x eq '%c' ? myvar%c :", cls,
i+96, i+96) }
cls=cls." 1/0 )
eval cls

# set all myvarX to NaN
cls=''
do for [ i = 1 : 26 ] { cls = sprintf("%s myvar%c = NaN;", cls, i+96) }
eval cls

# loop1
do for [ file in files1 ] {
fit ..... via ____myvar;
eval "myvar" . ind(file) . " = ____myvar"
}

# loop2, files2 can differ from files1
plot for [ file in files2 ] file t sprintf("fit: %.2g", myvar(ind(file)))

# loop3, whole range
all=''
do for [ i = 1 : 26 ] { all = sprintf("%s %c", cls, i+96) }
filename(x)="Data_".x.".dat"
plot for [ x in all ] filename(x) t sprintf("fit: %.2g", myvar(x))
''
-------------------------------

2, index an array by associate "internal" varnames ____<letter>____
for a..z with numbers 1..26:
``
# declare vars ____<letter>____
cls = ''
do for [ i = 1 : 26 ] { cls = sprintf("%s ____%c____ = %i;", cls, i+96, i) }
eval cls
# convert letter to index array (set 1 for "")
letter2number(c) = ( c eq "" ? 1 : value( "____".c."____") )
# filename format: Data_<letter>.dat
ind(filename)=letter2number(filename[6:6])

# set array myvar[26] to NaN
array myvar[26]
do for [ i = 1 : 26 ] { myvar[i] = NaN }

# loop1
do for [ file in files1 ] {
fit ..... via myvar[ind(file)];
}

# loop2, files2 can differ from files1
plot for [ file in files2 ] file t sprintf("fit: %.2g", myvar[ind(file)])

# loop3, whole range
array all[|myvar|]
do for [ i = 1 : |all| ] { all[i] = sprintf("%c", i+96) }
filename(x)="Data_".x.".dat"
plot for [ i = 1 : |all| ] filename(x = all[i]) t sprintf("fit: %.2g", myvar(x))
''
-------------------------------

3, index arrays via letters:
# currently not implemented.

``
# filename format: Data_<letter>.dat
ind(filename) = filename[6:6]

# set array myvar["a":"z"] to NaN
array myvar["a":"z"]
do for [ x = "a" : "z" ] { myvar[x] = NaN }

# loop1
do for [ file in files1 ] {
fit ..... via myvar[ind(file)];
}

# loop2, files2 can differ from files1
plot for [ file in files2 ] file t sprintf("fit: %.2g", myvar[ind(file)])

# loop3, whole range
filename(x)="Data_".x.".dat"
plot for [ x = "a" : "z" ] filename(x) t sprintf("fit: %.2g", myvar(x))
''
-------------------------------

disclaimer: the example code is not tested so it can miss some bracket etc.
-------------------------------

As I said I do not miss associative arrays yet, I'd preferred to find
a way without named letter variables (since they are not universal),
how to convert basic ascii letters to numbers as well.

Anyhow, implementing basic ascii letters as
predecessor/successor-system (in a way ``for [ x = "a":"g" ]'' would
be also nice -- at least looking intuitively in some cases.

Iva