[delta-l] Interactive vs automatic generation of conventional keys
Joseph.Kirkbride at ARS.USDA.GOV
Mon Jan 9 17:09:48 CET 2012
Please read my message of 28 October 1996 in the DELTA-L archive:
This is a description of how I wrote my first key using the DELTA software system. The was for 32 species, and ended up with 36 couplets. I had 203 morphological characters in the database, and attempted to include as many as possible in the key. A few of the species were highly variable, which greatly complicated building the key.
My second key built from DELTA-formatted data was for 435 genera of faboid legumes using 128 seed characters and 154 fruit characters. The key was supposed to use only seed characters, but in a few instances fruit characters were required to separate genera. I tried to use the KEY program of the DELTA system, but it was very difficult, and I could not imagine how many pieces that the key would have to be divided into. So I tried Kconi, and it would not even load the data because the matrix was so large. I contacted Richard Pankhurst, and obtained Big Kconi from him, which would load the data. I ended up with a master key to 16 subkeys, which each had 8-133 couplets. It took me about a month to prepare the key. You can peruse the final product in volume 1 of the resulting publication, which is online at:
Writing keys that work is never easy, no matter how you do it.
Joseph H. Kirkbride, Jr.
USDA-ARS, U.S. National Arboretum
Floral & Nursery Plants Research Unit
3501 New York Avenue NE
Washington, DC 20002-1958 USA
E-mail: joseph.kirkbride at ars.usda.gov
From: delta-l-bounces at science.uu.nl [mailto:delta-l-bounces at science.uu.nl] On Behalf Of Mike Dallwitz
Sent: Saturday, January 07, 2012 6:51 AM
Subject: [delta-l] Interactive vs automatic generation of conventional keys
- From: Hans Nooteboom
> Kconi ... allows you to choose the character you want, the most
> obvious (for the end user) or the character that divides the rest of
> the taxa in two equal portions. You can play with it to make the best
> key possible. Very easily you can make partial keys for different
> distributions, a key based on flowering specimens, and one based on
> fruiting specimens. And for the editors you really must make
> dichotomous keys. (At least for this editor).
> If you use DELTA's Key, this all is impossible or at least very
Both Kconi and Key generate conventional (printable) keys. Kconi works
interactively: the user (i.e. the author of the key) selects the
characters one by one, with the help of the program. Key works
automatically: when it is run, the whole key is generated without the
intervention of the user. Nevertheless, Key does allow the user to control
the generation of the key, by setting parameters beforehand.
I think it would usually be considerably quicker and easier to generate a
satisfactory key by using Key than by using Kconi.
The basic method of using Key is very easy. Within the DELTA Editor, run
the Confor action set 'tokey', which converts the DELTA data to the format
used by Key; then run a Key action set (e.g. 'key5'), which produces the
key. This takes only a few seconds.
The default action sets provided with the Editor will try to produce a key
having the smallest number of steps, averaged over all possible paths
through the key. But you will seldom be satisfied with this, so you will
need to refine the key by editing and rerunning the action sets.
(1) If you have numeric characters, they won't be used unless you divide
them into ranges with a KEY STATES directive in 'tokey'. E.g.
*KEY STATES 26,~2/2-5/5~
meaning 'up to 2', '2-5', and '5 or more'.
(2) Some characters are easier to use, or have a lower probability of
error. For these characters, set a higher 'reliability' in the Key action
set. You could use the reliabilities that you are (I hope!) using in
Intkey. Alternatively, start afresh and set higher reliabilities for your
preferred characters, and lower ones for poor or inaccessible characters.
The allowed values are 0 to 10, and the default value is 5. E.g.
*CHARACTER RELIABILITIES 26,9 27,8 44,8 45-47,7 69,1 70,2
If you have altered 'tokey' (or altered the DELTA data), rerun 'tokey'.
Then rerun the Key action set, and examine the resulting key. If you would
prefer different characters to be used at some places, change the relevant
character reliabilities (i.e. increase the reliabilities of characters
that you would prefer to be used, and/or decrease the reliabilities of
characters that you would prefer /not/ to be used).
Iterating this process a few times will usually produce a satisfactory
key. There are also other options available, e.g. how strongly the
character reliabilities influence the structure of the key, and how hard
the program tries to avoid taxa coming out more than once in the key. You
can also override the automatic character selection at any point in the
key. For details, see the chapter on Key in the User's Guide to the DELTA
To make special-purpose keys, e.g. for for vegetative, flower, or fruit
characters, specify the required characters with an INCLUDE CHARACTERS
directive in the Key action set, and (preferably) save it with a different
name, e.g. 'keyveg'. You might also need to make a few adjustments to the
reliabilities. With an interactive program, you would have to start again
If the DELTA data change, e.g. if new taxa are added, satisfactory new
keys will usually be obtained by simply rerunning the unchanged action sets.
To make strictly dichotomous keys, use the KEY STATES directive to combine
states as necessary, so that only 2 states remain. But I advise against
uncritically converting /all/ multistate characters in this way (unless
require by editorial policy), as it will often make the key more
cumbersome, and it may make some characters harder to use. For example,
is easier to use than
Flowers not blue
In the first form, the alternatives to 'blue' are immediately apparent. In
the second form, the user would be more likely to mistakenly deem a purple
flower to be blue - which would be a reasonable choice if the unspecified
alternatives comprising 'not blue' happened to be 'red or yellow' rather
than 'purple or white'.
Contact information: http://delta-intkey.com/contact/dallwitz.htm
DELTA home page: http://delta-intkey.com
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