[rrd-users] graph stack and negative values

[Simon Hobson]

Daniele Sluijters wrote:

>Never mind, I just realized my mistake.
>
>Forgot to put a divider line in it at 0, *shame*.

There's an easier, and better, way.

"CDEF:tierin=ds0,4,/",
"AREA:tierin#BFCFE4",
"AREA:tierin#80A0C9::STACK",
"AREA:tierin#4070AE::STACK",
"AREA:tierin#014194::STACK",

"CDEF:tierout=ds1,-4,/",
"AREA:tierout#FCE5BF",
"AREA:tierout#F9CB7F::STACK",
"AREA:tierout#F6B13F::STACK",
"AREA:tierout#F49800::STACK",

Just leave STACK off the first area in each group and it will be 
based on the Y=0 line.

Why is this better than adding a line at 0 to stack upon ?

If you do a line at 0, then that draws a line. If your data is 
missing, you still get a line unless you go to some trouble to get a 
dataset that's 0 when there's data and unknown when there isn't.
Just drawing the data as above, if the data is missing, you'll get a 
gap - not a line at 0, a complete break in the data which is what's 
normally wanted.

-- 
Simon Hobson

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