gnuplot-beta

problems interpretting missing data in csv data

[<pl...@pi...>]

Hi,

I have a csv file of about 2000 lines, which has some missing data, an 
extract :

25.12,141.99
25.14,141.91
25.16,141.71
25.18,
25.2,
25.22,


I thought gnuplot was quite good at guessing formats but it does not 
shine with csv, so to get it to read the csv it used
set datafile separator ","

Now whenever it hits one of these lines with missing data it plots 
points way off the the right in a way I have not managed to understand. 
x values are in the range circa 6500

I wondered whether the lcocal was doing odd things with the commas but 
it looks OK

LANG=
LC_CTYPE="POSIX"
LC_NUMERIC="POSIX"
LC_TIME="POSIX"
LC_COLLATE="POSIX"
LC_MONETARY="POSIX"
LC_MESSAGES="POSIX"
LC_PAPER="POSIX"
LC_NAME="POSIX"
LC_ADDRESS="POSIX"
LC_TELEPHONE="POSIX"
LC_MEASUREMENT="POSIX"
LC_IDENTIFICATION="POSIX"
LC_ALL=

why is gnuplot not correctly handling missing data in this case (and 
what is it actually reading to get x values around 6500) ?

I previously had problems with csv and think I ended up using awk to 
preprocess but it would be nice if gnuplot could make a better stab at 
this unless that compromises other things.

Am I just missing a trick ?

Thanks.

Re: problems interpretting missing data in csv data

[Ethan A M. <sf...@us...>]

On Thursday, June 14, 2012 04:17:56 am pl...@pi... wrote:
> Hi,
> 
> I have a csv file of about 2000 lines, which has some missing data, an 
> extract :
> 
> 25.12,141.99
> 25.14,141.91
> 25.16,141.71
> 25.18,
> 25.2,
> 25.22,
> 
> 
> I thought gnuplot was quite good at guessing formats but it does not 
> shine with csv, so to get it to read the csv it used
> set datafile separator ","
> 
> Now whenever it hits one of these lines with missing data it plots 
> points way off the the right in a way I have not managed to understand. 
> x values are in the range circa 6500

I suspect you have run into a very old, very strange, "feature" of gnuplot.
Fortunately, it has recently been banished in the CVS version.

Please read the section in the User Manual about "set datafile missing".
In particular please have a look at the figure and explanation on page
105 of the User Manual for 4.7:
   http://gnuplot.sourceforge.net/gnuplot_cvs.pdf

> Am I just missing a trick ?

You didn't actually show us the plot command.
I am guessing that you neglected to provide a "using" specifier in the
plot command.  As explained in the link above, this [used to] do bad things
if not all the input lines have the same number of data fields.

Switch to the current cvs version and/or add "using 1:2" in the plot command.