Re: [Gnuplot-info] Histograms with dates on the X axis

[Steve C. <sc...@ja...>]

CLOSE Dave wrote:
> Hans-Bernhard Bröker wrote:
> 
>>> A little searching hints that this message may be somewhat misleading.
>>> That what it really means is that a "format" must be added.
>> Where your searching let you think you found this, it's wrong.
>>
>> The error message means exactly what it says: you don't have sufficient
>> 'using' specifiers.  It makes little sense to mix
>> xticlabels/histogramming with time/date features.  The former treat the
>> input as strings without any numerical meaning by design, the latter is
>> a means of extracting a numerical meaning out of human-readable
>> date/time strings.  So I think you should just forget about 'xdata time'
>> and plot your input as it is.
> 
> Thanks for the reply.
> 
> My code says,
>  plot "/tmp/file" using 2:xtic(1), "/tmp/file" using ($3+$4+$5+$6+$7) axis x1y2
> I've tried it without the :xtic(1) and still get the error. The help screen for "set style histogram" says, "Each element of the `plot` command must specify a single input data source (e.g. one column of the input  file), possibly with associated tic values or key titles", so I have trouble understanding what additional using specifier I could add.
> 
> The data file looks like this:
> 2009-01 1 1 0 0 0 0
> 2009-02 1 1 0 0 0 0
> 2009-03 3 9 0 0 0 0
> 2009-04 6 6 0 0 3 4
> 2009-05 11 14 3 3 0 4
> 2009-06 10 2 18 7 4 5
> 2009-07 12 18 31 7 6 13
> 2009-08 10 10 37 6 9 22
> 2009-09 14 25 45 8 13 24
> 2009-10 16 19 47 18 16 3
> 2009-11 14 24 29 7 6 3
> 
> I supposed I could drop the year and plot against the month -- for now. But this won't work once the file contains two more lines, as it will in little more than a month.
> 
> Can you suggest the actual commands needed?
> 
> 	Dave Close
> 
> 
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> 

Having recently swum in these same shark-infested waters myself (I am
not a developer of this project, just a user like you) I would first get
rid of
set xdata time
set timefmt "%Y-%m"
set format x "%m\\n%Y"

Histograms and these time functions simply don't mix.  At all.

You will, of course, then, not see labels on your x-axis, but you should
at least see a graph.

Now, for those x-axis labels, Gnuplot's string functions are your friend:

plot "/tmp/file" using
2:xtic(substr(stringcolumn(1),6,7)\\nsubstr(stringcolumn(1),1,4),
"/tmp/file" using ($3+$4+$5+$6+$7)
axis x1y2

should get you what you need.  (I don't see this documented anywhere but
Gnuplot's substring() function appears to use 1-based indexing.)