Re: [Fwd: [ILUG] gnuplot datafile with rows]

[Ethan M. <merritt@u.washington.edu>]

On Thursday 26 January 2006 01:36 am, Lars Hecking wrote:
>  Can anyone help with this?
>
> ----- Forwarded message from Karine Dionne <k.d...@ja...>
>
> I am new to Gnuplot and to Linux as well and I am having a bit a
> struggle right now.  Here is the format of my datafile:
>
> Day	Power1	Power2	Power3	Power4	...
> Day1	y1	y1	y1	y1	...
> Day2	y2	y2	y2	y2	...
> Day3 	y3	y3	y3	y3	...

gnuplot 4.1  (Note version number!)

#Day along x;  Power reading on y
# (Note: You must uncomment the first line of your data file
#             if you want it to be used for generating key titles)
#
set style data lines
set key autotitle columnhead
plot 'datafile'  using 2:xtic(1), '' using 3, '' using 4, '' using 5


# Power along x; Day on y
# This *almost* works, but I'm having trouble getting it
# to skip the non-numeric data in the 1st column
# I think there's a bug in the program :-(
#
set style data lines
plot 'datafile' matrix using 1:3 every 1:999:1:0, \
        '' matrix using 1:3 every 1:999:1:1, \
        '' matrix using 1:3 every 1:999:1:2, \

The "matrix using 1:3"  causes it to plot rows
The "every 1:999:<start column>:<start row>"
selects which row and which column to start with.
Row and column numbering starts at 0, so putting a
1 for <start column> should skip the first column of data.
Unfortunately this is where the bug creeps in; it will skip
the first column if the column contains a number, but 
complains "Bad number in matrix" if the contents are
non-numeric.   I'll see if I can fix that bug this weekend,
but for now you will have to pre-filter the input to remove
the first column using some appropriate utility like
sed, awk, perl, or egrep.   Here I use sed to strip out
leading non-blank characters from each line:

plot "< sed -e 's/^[^ ]*//' datafile" using 1:3 every 1:999:0:0, \
 "" matrix using 1:3 every 1:999:0:1, \
 "" matrix using 1:3 every 1:999:0:2, \
        etc for all the rows

If you want to hit all of the rows together in one command,
leave out the "every" clause:
  plot "< sed -e 's/^[^ ]*//' datafile" using 1:3


So yeah, it's possible.
But your specific request seems to have uncovered a bug
in the "every" behaviour, so you will need to use some
annoying work-around like my sed command above until
that's fixed.

		Ethan



>
> "DayX" is actually a date string, but that is not my problem
> for now.  Each column is a power measurement  given by a specific
> powermeter.  There are two types of plots I need to do.
>
> To begin, I want to compare the performance of each powermeter on a
> single plot.  So, I would need to generate an X vector for the
> powermeters' IDs (from 1 to 32 in steps of 1) and I don't know how to
> do that.  I would also need to be able to tell gnuplots to proccess
> rows, not columns. I browsed the internet and the mailing lists, I
> found one thread about it. It was in March 2000 and it says that you
> have to reformat your file in another file and then plot the columns.
>
> There are 2 reasons why I don't want to do that.  First of all, this
> is a log file that will become very big with time.  I am not
> interested in having to keep two copies of them.  I could keep only
> the transposed copy, but this solution is not possible because of the
> second type of plot I need.  I want to track the changes with time of
> the power meters.  I will use the date string as the X axis and the
> other columns as Y.  So, one way or another, I have to access rows of
> data for one of my two plots.
>
> I would like to know if there is a possibility to do that with
> gnuplot or if I should consider using something else that could do
> the job.  I with to find something efficient and as straight forward
> as possible.  I hope I am not asking for to much.
>
> Thanks for your time and expertise.
>
> Karine
>
> ----- End forwarded message -----
>
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-- 
Ethan A Merritt
Biomolecular Structure Center
University of Washington, Seattle WA