[rrd-users] Re: graph problem

[Alex van den Bogaerdt]

On Tue, Aug 16, 2005 at 03:59:16PM +0200, David Thamm wrote:
> Hi List,
> i want to graph integer values. My problem is that the values in the
> graph are floatingpoint values (see attachment).
> 
> the graphic was created with this line:
> rrdtool graph demo60.png  --step 60 DEF:hdosis=fr.rrd:hoch:AVERAGE
> AREA:hdosis#ffa000:""

[I modified the next table for nicer formatting]

> <!-- 15:41:00 --> <row><v> 27 </v><v> 1 </v></row>
> <!-- 15:42:00 --> <row><v> 20 </v><v> 1 </v></row>
> <!-- 15:43:00 --> <row><v> 23 </v><v> 0 </v></row>
> <!-- 15:44:00 --> <row><v> 21 </v><v> 1 </v></row>
> <!-- 15:45:00 --> <row><v> 20 </v><v> 0 </v></row>
> <!-- 15:46:00 --> <row><v> 18 </v><v> 1 </v></row>
> <!-- 15:47:00 --> <row><v> 19 </v><v> 2 </v></row>
> <!-- 15:48:00 --> <row><v> 20 </v><v> 1 </v></row>
> <!-- 15:49:00 --> <row><v> 15 </v><v> 0 </v></row>
> <!-- 15:50:00 --> <row><v> 24 </v><v> 0 </v></row>
> <!-- 15:51:00 --> <row><v> 23 </v><v> 1 </v></row>
> <!-- 15:52:00 --> <row><v> 23 </v><v> 0 </v></row>
> <!-- 15:53:00 --> <row><v> 23 </v><v> 2 </v></row>


So, which of the two columns do you graph?  I guess the 2nd column.

You are showing 1-minute rows.  Your graph is 24 hours, that's
1440 minutes.  The graph-width is 400 pixels (the inside-canvas).

This means you have 1440/400 = 3.6 minutes per pixel-column. For this
discussion, let's say it is 4 minutes per column, that means graph
four of your values at the same time.

15:40 to 15:44 :  (1+1+0+1)/4 = 0.75
15:44 to 15:48 :  (0+1+2+1)/4 = 1.00
15:48 to 15:52 :  (0+0+1+0)/4 = 0.25

As you can see, you are NOT graphing integer values.  You programmed
RRDtool to do this averaging for you.

> how can i graph integer values?

Display 400 minutes at a time when the image is 400 pixels wide.
(change "400" in any number, both instances).

Or display MIN, MAX or LAST in stead of AVERAGE.

Study the documentation about this.  I'm sure it is described somewhere.

Alex

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