[18876] in s-news-athena
[S] speeding up function
daemon@ATHENA.MIT.EDU (=?iso-8859-1?Q?"G=E9rald_Jean"?=)
Thu Aug 5 14:49:55 1999
From: =?iso-8859-1?Q?"G=E9rald_Jean"?= <Gerald.Jean@spgdag.ca>
To: s-news@wubios.wustl.edu
Message-Id: <852567C4.00652A6C.00@mail.spgdag.com>
Date: Thu, 5 Aug 1999 14:37:44 -0400
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Dear S+ users,
I wrote the following function, see purpose in function's body, and it is
very, very, very slow. I am running S+ 2000, on a Pentium II, 350Mz, 192M
RAM machine. Can anyone point out why is it so slow and possible
improvements (my input data frames have over 100K obs.) and also why the
second column of "df", which is numeric to start with, has become character
once each row of "df" is passed in turn to the function inside apply which
forces me to coerce it to numeric again?
Thanks to all
Gérald Jean
Analyste-conseil (statistiques), Actuariat
télephone : (418) 835-8839
télecopieur : (418) 835-5865
courrier électronique: gerald.jean@spgdag.ca
"In God we trust all others must bring data"
"correctionformule" <- function (df,diff)
{
# Author : Gerald Jean
# Date : August 1999
# Purpose: the function will mutiply the second column of "df" by one of
the
# elements of "diff" depending on the level of the first column
# factor.
# Parameters:
# df : normally a 2 column subset of a data frame, the first column is a
# factor while the second is a numeric column.
# diff : one of it's element will multiply the second column of "df"
# conditionnal on the value of the first column of "df".
assign("diff", diff, frame = 1)
ttt <- apply(df, 1, function(x) {
y <- as.numeric(x[2])
switch(x[1], 'En confort '= y * diff[1],
'Commodite '= y * diff[2],
'Restreinte '= y * diff[3],
'Plein confort'= y *
diff[4])})
ttt
}
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