I did a few measurements for discharging batteries. Now i wanted to plot them with Gnuplot. The problem is, that one of the measurements startet very late, that I have an "overflow" from my 24hours-clock.

Here an example of my problem-.csv-measurement data:

Time;Voltage;Current;Charge;Power;Energy;Temperature
...
23:59:54;3.2387;0.6989;0.039;2.264;0.127;22.0
23:59:55;3.2387;0.6989;0.039;2.264;0.128;22.0
23:59:56;3.2387;0.6989;0.039;2.264;0.129;22.0
23:59:57;3.2387;0.6989;0.04;2.264;0.129;22.0
23:59:58;3.2387;0.6992;0.04;2.264;0.13;22.0
23:59:59;3.2386;0.6989;0.04;2.263;0.13;22.0
00:00:00;3.2386;0.6992;0.04;2.264;0.131;22.0
00:00:01;3.2386;0.6989;0.04;2.263;0.132;22.0
00:00:02;3.2386;0.6992;0.041;2.264;0.132;22.0
00:00:04;3.2386;0.6992;0.041;2.264;0.133;22.5
00:00:05;3.2386;0.6989;0.041;2.263;0.134;22.5
00:00:06;3.2386;0.6989;0.041;2.263;0.134;22.5
00:00:07;3.2386;0.6989;0.041;2.263;0.135;22.0

the other datas dont measured between two days.

With the following Gnuplot-code:

set grid
set title 'Entladungen der Batterie über Zeit'
set tics nomirror
set title font ",12"
set ylabel 'U/V' font ",12"
set key box font ",12"
set xtics time
set xlabel 'time' font ",12"
set border 11
set border lw 2
set xtics font ",8"
set term wxt size 1200, 460
myFmt = "%H:%M:%S"
set datafile separator ";"
set format x "%tH:%M:%S" #timedate
set yrange[2.6:3.7]

plot 'Entadung_4,2A_Temp_22,5C°.csv' u (t=timecolumn(1,myFmt), $0==0?t01=t:0, t-t01):2 every ::2::1061 lt 7 lc "blue" with lines      ti "Entladung bei 3C", \
     'Entadung_2,8A_Temp_22,5C°.csv' u (t=timecolumn(1,myFmt), $0==0?t02=t:0, t-t02):2 every ::2::1604 lt 7 lc "web-green" with lines ti "Entladung bei 2C", \
     'Entadung_1,4A_Temp_22,0C°.csv' u (t=timecolumn(1,myFmt), $0==0?t03=t:0, t-t03):2 every ::2::3267 lt 7 lc "red" with lines      ti "Entladung bei 1C",\
     'Entadung_0,7A_Temp_22,0C°.csv' u (t=timecolumn(1,myFmt), $0==0?t04=t:0, t-t04):2 every ::2::6696 lt 7 lc "yellow" with lines ti "Entladung bei 0,5C", \
     'Entadung_0,28A_Temp_22,0C°.csv' u (t=timecolumn(1,myFmt), $0==0?t05=t:0, t-t05):2 every ::2::16977 lt 7 lc "black" with lines      ti "Entladung bei 0,2C",\
     'Entadung_0,14A_Temp_22,5C°.csv' u (t=timecolumn(1,myFmt), $0==0?t06=t:0, t-t06):2 every ::2::33731 lt 7 lc "violet" with lines      ti "Entladung bei 0,1C"

I got this output:

The plot takes the 23 hours and subtract ist from every timestep. So i get negative time...

Anybody know, how i can use an offset just for this one data, that the others stay untouched?

I was expecting, that the yellow graph lays between the red and the black graph.

CodePudding user response：

Unfortunately, you don't record the date as well. If you had you wouldn't have this problem.

But you can account for midnight crossings with a little addition.

• assign t1=NaN and td=0 before the plot command
• within the plot command (loop), assign t0=t1 and directly afterwards t1=timecolumn(...). So, t0 always holds the previous value and t1 the current value
• every time t1<t0 (i.e. crossing midnight) add one day to td, i.e. td=td secsPerDay (number of seconds per day) and add td to your plotting value.
• furthermore, if you use %tH as x-timeformat, hours will not wrap at 24 hours, in case your measurement runs for longer than 24 hours (check help time_specifiers).

Script:

### account for midnight crossings
reset session

$Data <<EOD
23:59:00   3.7
01:59:00   3.6
12:00:00   3.5
23:00:00   3.4
02:30:00   3.3
13:00:00   3.2
23:00:00   3.1
03:00:00   3.0
14:00:00   2.9
EOD

myFmt = "%H:%M:%S"
secsPerDay = 3600*24

set xlabel "hours:min"
set format x "%tH:%M" timedate

set multiplot layout 2,1

    plot $Data u (t=timecolumn(1,myFmt), $0==0? t01=t:0, t-t01):2 w lp pt 7 lc "red" ti "as is"
    
    plot t1=(td=0,NaN) $Data u (t0=t1,t1=timecolumn(1,myFmt), $0==0? t01=t1:0, \
         t1<t0?td=td secsPerDay:0, t1-t01 td):2 w lp pt 7 lc "blue" ti "add day offset"
    
unset multiplot
### end of script

Result: