> I have a table of regions with currency amounts against each region. I
wish
> to thematically map the ratio of the currency amount for each region to
the
> average (currency amount) for all regions.  The averages are not recorded
> in the table.

You *can* set up a MapInfo workspace to automatically recreate the map
based upon the current average if the exchange values in the table change:

1. Create the initial map, without a thematic layer.
2. Paste the five lines below into the MapBasic window:

dim av as float
select avg(euros) "av_euro" from ExchangeRates into avrg noselect
fetch first from avrg
av=avrg.av_euro
close table avrg

Select them all, and hit ENTER.

3. Create a thematic map, but create it on the expression euros/av.

4. Now to save your work.  Every time you save the workspace file,
you have to perform the following steps on it (it won't open otherwise):

a. Open it up in a text editor.

b.  Just after the Open Table statements, paste the same five lines that
you pasted into the MapBasic window in step 2.

c. Scan down the workspace for a statement that says

Shade # with euros/_var_

where # is a layer number.  Change the _var_ bit to "av".

d.  After the very last line of the workspace, type

Undim av

(you will also need to type "Undim Av" in the MapBasic
window before reopening the workspace file for the first time).

HTH
Spencer



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