[SOLVED] [Gnuplot] Plot a log file

gregors · 02-10-2019, 08:18 AM

Hi there!

I have a log file containing lines like this:

Code:

2019-02-10 03:53:54, 24, 40

That's date and time of the log entry, temperature in °C and RH (%)

Since I like plotting log files and have done that many times I thought that it can't be that hard. But I never had to deal with date/time things and that gave me some headache yesterday ...

So this is the last version of my gnuplot-script:

Code:

#!/usr/bin/gnuplot

FN = "/home/gszaktilla/log.txt"

set terminal postscript
set output "/tmp/plot.ps"

set xlabel "Datum"
set ylabel "°C bzw. %RH"
set title FN

set format x "%Y-%m-%d %H:%M:%S"
#set xdata time

set grid

plot FN using 1:2 notitle with lines

#eof

And the response I get is

Code:

"./diag.sh", line 18: Bad format character

Is there someone who knows what format string I have to use to plot my file?

TIA

Gregor

PS: The log files I played with usually look like the ones described here: http://html.szaktilla.de/weekender/2.html

scasey · 02-10-2019, 10:04 AM

Please refer to the Time/date specifiers section in the gnuplot manual at gnuplot.info

The formats you've specified for hours, minutes and seconds is not correct.

gregors · 02-10-2019, 10:10 AM

Quote:

Originally Posted by scasey

Please refer to the Time/date specifiers section in the gnuplot manual at gnuplot.info

The formats you've specified for hours, minutes and seconds is not correct.

What do you think what caused yesterdays headache?! Believe it or not, I already spent some time reading docs. I am hoping that someone here knows gnuplot good enough to tell me what the problem is.

Regards,

Gregor

scasey · 02-10-2019, 10:26 AM

I appreciate the frustration.
I had to look it up. Took me about 2 minutes.
I pointed you at the specific place in the documentation...

Code:

Time Specifiers
Format     Explanation
%tH     +/- hours relative to time=0 (does not wrap at 24)
%tM     +/- minutes relative to time=0
%tS     +/- seconds associated with previous tH or tM field

gnuplot is extremely complex...as it needs to be for the functionality it provides.
Bookmark the handbook...

gregors · 02-10-2019, 10:44 AM

Quote:

Originally Posted by scasey

I appreciate the frustration.
gnuplot is extremely complex...as it needs to be for the functionality it provides.
Bookmark the handbook...

Thanks a lot!

The docs I read didn't mention the t after the percent sign. I'll re-read and double check I didn't overlook something.

Gregor