# Re: min and max contours

```At 1:53 pm -0500 22/3/01, Andrew Wittenberg wrote:
>Hi Glenn,
>
>The simplest way is to specify extra contours beyond the range of your
>data:
>
>yes? fill/lev=(-1000)(1,10,1)(1000) data
>
>This will give -1000->1, 1->2, 2->3, ... 9->10, 10->1000.
>
>If you actually want to see the min and max on the plot, here's one way to
>do it.  First define variables to contain the min and max of a dummy
>variable called "data":
>
>let min = data[x=@min,y=@min]
>let max = data[x=@max,y=@max]
>
>Then define "data" and plot it, say for February SST in the tropical
>Pacific:
>
>let data = sst[x=120E:90W,y=20S:20N,l=2]
>fill/lev=(`min`)(24,28,1)(`max`) data

Both the:
fill/lev=(-1000)(1,10,1)(1000) data
and
fill/lev=(`min`)(24,28,1)(`max`) data

get very close to what I want. However, both will put a label for the
minimum and maximum value on the colour scale which is not what I
want. I want ferret to colour fill from the minimum value up to the
first contour level I specify but ONLY label the min and max contour
level.

Although I can achieve the colour fill I want with the approaches
above, they presuppose I know my minimum value beforehand. The second
approach using `min` will not work if `min` turns out to be greater
than '24', my first contour level (as I discovered when I was playing
with this!).

So there's 2 issues here really. One is that it would be nice to have
a slightly different mode of plotting contours where ferret fills
from the 'data min' to the first contour level (similarly for max)
rather than use the above which is not entirely satisfactory.

The second issue is the colour bar where ideally I don't want the
`min` and `max` values appearing. So something like:

[purple] [blue] [green] [red]
2      4       6

rather than what ferret does now :

[purple] [blue] [green] [red]
2       3      4       5     6

As far as I know it's not possible to do this in ferret? I've seen
other graphics packages do it this way and it just so happens for a
particular situation I'm in now it would be useful. Sorry I wasn't
precise enough in my last email!

I attach a "doctored" gif image of the kind of effect I'm trying to
get. The plot was produced by doing:
CONTOUR/FILL/lev=(`min`)(240,400,20)(`max`) to3
but then I've rubbed out the min and max values in a graphics program.

Thanks for the help.

Glenn
```

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```--

Dr. Glenn Carver, Senior Research Associate,
Centre for Atmospheric Science, Chemistry Dept., Cambridge University, UK
mailto:Glenn.Carver@atm.ch.cam.ac.uk   http://www.atm.ch.cam.ac.uk/~glenn/

"Do not worry about growing old, it is a privilege denied to many "
- Anon.
```