| Re: Function names (was mean and sdev) [message #11041] |
Thu, 05 March 1998 00:00  |
wmc
Messages: 117
Registered: February 1995
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Senior Member |
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In article 2748ae80@p4.psych.uiuc.edu, "Kevin Spencer" <kspence1@uiuc.edu> writes:
> Brian Jackel <jackel@danlon.physics.uwo.ca> wrote in article
> <6dhu2f$eoi@ds2.acs.ucalgary.ca>...
>> Dr. G. Scott Lett wrote:
>>> The MOMENT function is obscure and slow when all you need is
>>> the mean and standard deviation, so we're adding the more obvious
>>> MEAN, STDDEV, VARIANCE and other statistics functions for IDL 5.1.
>> I'm not sure who the "we" above refers to, but I'd like to
>> make a general comment. IMHO IDL is already dangerously
>> cluttered with lots of special purpose functions that could
>> perhaps be more usefully bundled together.
> I've been very annoyed at RSI's inconsistent support for these
> simple statistical functions. There used to be a "stdev" procedure,
> then (if I recall correctly) one like it with a similar name. In IDL 5,
> they got rid of these functions and replaced them with "moment".
> Now according to Scott Lett, who I assume works for RSI, they
> are going to have another standard deviation procedure, plus one
> for computing the mean and another for the variance. Why did
> they get rid of stdev in the first place? And calculating the mean
> is trivial; just use total(x)/n_elements(x).
If they do introduce a function called stddev, instead of recalling stdev from
"obsolete", they will be very silly indeed (its still useable in IDL 5 BTW, just
not in the help).
There is disagreement between those who like things bundled together (the
"momentists") who are presumably happy to write av=total(x)/n_elements(x)
in order to avoid having a "mean" or "avg" function defined, and those who
don't really mind having piles of extra functions lying around in order to write
shorter and more comprehensible code (I'm in the latter camp).
To some extent this could be fixed by putting all the extra functions in a separate
directory whose name you could remove from the !PATH if you wanted to. Presumably,
if you don't want to see the obsolete functions you can remove "obsolete" from the
!PATH.
- William
---
William M Connolley | wmc@bas.ac.uk | http://www.nbs.ac.uk/public/icd/wmc/
Climate Modeller, British Antarctic Survey | Disclaimer: I speak for myself
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