Re: Plot

[Gordon Haverland]

On Fri, 31 Mar 2017 20:41:29 -0700
"Thomas D. Dean" <address@hidden> wrote:

> I exercise for twenty minutes, two times per day, with the heart rate 
> monitor generating a reading every second.  If I start at 10AM, I
> have 1200 samples with time stamps of 10:00:00. 10:00:01, etc.  If I
> start again at 2PM, I have 1200 samples with time stamps of 14:00:00, 
> 14:00:01, etc.  So, my data file has two columns, a time stamp and a 
> heart rate.  But the data is not evenly spaced in time.

Sorry if I missed something earlier.

This is concatenated data.  Just like using the cat command to
concatenate text files.

If Thomas was to plot this as a vector of time and a vector of value,
most of the graph would be "no data".  Which isn't very interesting.
If he was to just concatenate all the values from all the files, and
plot that, the default plotting (say connecting points) is going to
connect the last value from set N with the first value of set N+1.

I think what Thomas would like, is something like a double vertical bar
to go across the graph at the points where the data "breaks".
1 1.9
2 2.0
3 2.1
4 2.15
...
91 2.4
92 2.38

642 1.84
643 1.95
644 1.98
...
754 2.33
755 2.36

1824 1.87
1825 1.92
1826 1.91
...

What I think Thomas wants, is for that data point for 642, to be
plotted as if it was say 94, and have something like a double bar to
indicate there is a break in the data.  And  better than that, to have
the X labels still show the proper time.  Not the "adjusted" times to
get all these little plots to come up concatenated with each other.

After the first "break" in the data, the times are considered as if
they were (for instance) t-548 instead of t.  After the second gap, we
would be plotting something like t-1615 instead of t.

In gnuplot, it is related to the difference between
 plot '-' using 1:2
and
 plot '-' using 1:($2)

In a particular blog entry about gnuplot
 http://gnuplot-tricks.blogspot.ca/2010/06/broken-axis-once-more.html
the last plot shows a "broken" set of data.  It is two plots to
gnuplot, but it is displayed as a single plot.  There is some magic
being used to get the "slashes" on the left and right graph boundaries
to show there is a break in the data, and the plot itself does not try
to connect the last point of the first set to the first point of the
second set.

I think Thomas is looking for the horizontal analog to this kind of
plot (this one being vertical).

Or maybe I haven't had enough coffee today.  :-)

Gord