Can you use the graphed time interval in a CDEF function?

[Marc MERLIN-4]

If I'm graphing something like this
http://gargamel.merlins.org/cacti/graph.php?action=zoom&local_graph_id=19&rra_id=0&view_type=&graph_start=1258012800&graph_end=1258099199&graph_height=320&graph_width=800&title_font_size=10

Is there a way to take my average values and auto-multiply them by the time
range?
That way if I take avg val * 24H in the graph above it would give me
Kwh/day.

Thanks,
Marc
--
"A mouse is a device used to point at the xterm you want to type in" - A.S.R.
Microsoft is to operating systems & security ....
                                      .... what McDonalds is to gourmet cooking
Home page: http://marc.merlins.org/ 

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[A Darren Dunham]

On Fri, Nov 13, 2009 at 07:11:54AM -0800, Marc MERLIN wrote:
> If I'm graphing something like this
> http://gargamel.merlins.org/cacti/graph.php?action=zoom&local_graph_id=19&rra_id=0&view_type=&graph_start=1258012800&graph_end=1258099199&graph_height=320&graph_width=800&title_font_size=10
>

Those labels seem odd to me.  If you're measuring power at a point in
time, wouldn't that be in Kw, not Kwh (a unit of energy)?

> Is there a way to take my average values and auto-multiply them by the time
> range?
> That way if I take avg val * 24H in the graph above it would give me
> Kwh/day.

I don't see why you'd want to depend on the time range of the graph.  If
your graph was 22 hours, wouldn't you still want to see Kwh/day and
therefore still multiply by 24?

If you do want the time range, I think you'd have to graph something
twice.  The first one doesn't have to have all the data, but you can get
the range info from it with graphv.  Then use that information to create
the second graph.

--
Darren

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[Marc MERLIN-4]

On Fri, Nov 13, 2009 at 05:41:47PM +0000, A Darren Dunham wrote:
> On Fri, Nov 13, 2009 at 07:11:54AM -0800, Marc MERLIN wrote:
> > If I'm graphing something like this
> > http://gargamel.merlins.org/cacti/graph.php?action=zoom&local_graph_id=19&rra_id=0&view_type=&graph_start=1258012800&graph_end=1258099199&graph_height=320&graph_width=800&title_font_size=10
> >
>
> Those labels seem odd to me.  If you're measuring power at a point in
> time, wouldn't that be in Kw, not Kwh (a unit of energy)?

True, I should label kw.

> > Is there a way to take my average values and auto-multiply them by the time
> > range?
> > That way if I take avg val * 24H in the graph above it would give me
> > Kwh/day.
>
> I don't see why you'd want to depend on the time range of the graph.  If
> your graph was 22 hours, wouldn't you still want to see Kwh/day and
> therefore still multiply by 24?

No. I might want to see a week's worth or a month's worth or whatever range
I zoomed on.
For instance how much electricity did I use in august, or how much AC did I
use last week.

> If you do want the time range, I think you'd have to graph something
> twice.  The first one doesn't have to have all the data, but you can get
> the range info from it with graphv.  Then use that information to create
> the second graph.

I'm not familiar with graphv, but can I do it on a dynamic basis based on
the range I just selected to render as a rrdtool graph with cacti or from
the command line?

Thanks,
Marc
--
"A mouse is a device used to point at the xterm you want to type in" - A.S.R.
Microsoft is to operating systems & security ....
                                      .... what McDonalds is to gourmet cooking
Home page: http://marc.merlins.org/ 

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[A Darren Dunham]

On Wed, Nov 18, 2009 at 12:02:33AM -0800, Marc MERLIN wrote:
> > I don't see why you'd want to depend on the time range of the graph.  If
> > your graph was 22 hours, wouldn't you still want to see Kwh/day and
> > therefore still multiply by 24?
>
> No. I might want to see a week's worth or a month's worth or whatever range
> I zoomed on.
> For instance how much electricity did I use in august, or how much AC did I
> use last week.

Okay, so you want to compute cumulative engery usage.  I think I was
thinking you just wanted to scale the units.  

> > If you do want the time range, I think you'd have to graph something
> > twice.  The first one doesn't have to have all the data, but you can get
> > the range info from it with graphv.  Then use that information to create
> > the second graph.
>
> I'm not familiar with graphv, but can I do it on a dynamic basis based on
> the range I just selected to render as a rrdtool graph with cacti or from
> the command line?

Yes.  Use 'graphv' instead of 'graph', and it returns details about the
graph, including the 'start' and 'end' times.  So you might have to
graph twice.  Once to get the times, then again after you have that
information.  

--
Darren

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