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format x axis as date/time

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  format x axis as date/time Randy Wilkinson <randallcwilkinson@gmail.com> - 2021-12-07 15:50 -0800
    Re: format x axis as date/time Jörg Buchholz <bookwood4new@freenet.de> - 2021-12-08 07:51 +0100
      Re: format x axis as date/time Randy Wilkinson <randallcwilkinson@gmail.com> - 2021-12-08 06:53 -0800

#4445 — format x axis as date/time

I am trying to figure out how to format the x axis of my plot using date and time.  I have sensor measurement readings that are recorded every few minutes over multiple days.

My data file looks like this excerpt:

11/19/2021 11:36:01,717.9,70.2,33.4
11/19/2021 11:42:01,701.5,70.8,33.6
11/19/2021 11:48:01,692.5,71.2,32.7
11/19/2021 11:54:01,695.4,71.3,32.0
11/19/2021 12:00:01,699.8,71.4,31.5
11/19/2021 12:06:01,698.9,71.7,31.1
11/19/2021 12:12:01,697.3,71.9,30.7
11/19/2021 12:18:01,711.6,72.1,30.5
11/19/2021 12:24:01,765.9,72.3,30.3
11/19/2021 12:30:01,747.0,73.7,29.0
.
.
.

My gnuplot settings are currently like this:

set datafile separator comma
set title "CO2 Measurements" font ",20"
set xdata time
set timefmt "%m/%d/%Y %H:%M:%S"
set y2range [32:100]
set autoscale y
#set autoscale y2
set format x "%m/%d/%Y %H:%M"
set ylabel "CO2, PPM"
set y2label "Temperature, Degrees F"
set grid
set border
set style data lines
plot 'CO2logfile-25Nov21.csv' using 0:2, '' using 0:3, '' using 0:4

It looks like plot does not ready the time correctly from my data file.  It seems to only be reading the seconds.  I'd like the x axis to indicate the date and time for measurements from the data file.

Any suggestions appreciated!   Randy

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#4446

On 08.12.2021 00:50, Randy Wilkinson wrote:

> plot 'CO2logfile-25Nov21.csv' using 0:2, '' using 0:3, '' using 0:4
> 
> It looks like plot does not ready the time correctly from my data
> file.  It seems to only be reading the seconds.  I'd like the x axis
> to indicate the date and time for measurements from the data file.
> 
> Any suggestions appreciated!   Randy
> 


column 0 is a "pseudo-column", your date is in column 1.

Jörg

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#4447

On Tuesday, December 7, 2021 at 10:51:48 PM UTC-8, Jörg Buchholz wrote:
> On 08.12.2021 00:50, Randy Wilkinson wrote: 
> 
> > plot 'CO2logfile-25Nov21.csv' using 0:2, '' using 0:3, '' using 0:4 
> > 
> > It looks like plot does not ready the time correctly from my data 
> > file. It seems to only be reading the seconds. I'd like the x axis 
> > to indicate the date and time for measurements from the data file. 
> > 
> > Any suggestions appreciated! Randy 
> >
> column 0 is a "pseudo-column", your date is in column 1. 
> 
> Jörg
I thought I tried that.  It works as expected using column 1 instead of 0.  Thanks!  Getting out the docs to find out what a pseudo-column is....Randy

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