I'm not sure why the min does not work in the by() function. I have
provided a method that does work.
Also, please be careful about the way you create the data. When you mixed
character and numerics in the vectors, it coerces all to characters. When
you created your dataframe, everything comes out as character. Check out my
example as how to create the dataframe I think you wanted.
tempdata<-as.data.frame(matrix(NA,4,4))
names(tempdata)<-c("yearmon","h0","h1","name")
tempdata[1,]<-c(200602,1,4,"abvol")
tempdata[2,]<-c(200603,2,3,"abvol")
tempdata[3,]<-c(199106,3,2,"accr")
tempdata[4,]<-c(199107,4,1,"accr")
is.numeric(tempdata$yearmon)
tempdata <- data.frame(yearmon= c(200602, 200603, 199106, 199107),
h0 = 1:4,
h1 = 4:1,
name = c(rep(c('abvol', 'accr'), each = 2)))
is.numeric(tempdata$yearmon)
by(tempdata[, 1], tempdata$name, mean)
by(tempdata[, 1], tempdata$name, function(x) min(x))
--Matt
Matt Austin
Statistician
Amgen, Inc
800 9AMGEN9 x77431
805-447-7431
-----Original Message-----
From: s-news-owner@lists.biostat.wustl.edu
[mailto:s-news-owner@lists.biostat.wustl.edu]On Behalf Of Kurbat, Matt
BGI SF
Sent: Thursday, April 13, 2006 7:15 PM
To: s-news@lists.biostat.wustl.edu
Subject: [S] "by" question
Hello,
I've recently returned to Splus after a long layoff (forced SAS treatments).
I'm trying to apply "by" for various input functions and datasets and having
trouble getting it right.
For example, I can create a dataframe as follows:
tempdata<-as.data.frame(matrix(NA,4,4))
names(tempdata)<-c("yearmon","h0","h1","name")
tempdata[1,]<-c(200602,1,4,"abvol")
tempdata[2,]<-c(200603,2,3,"abvol")
tempdata[3,]<-c(199106,3,2,"accr")
tempdata[4,]<-c(199107,4,1,"accr")
With results that look like this:
> tempdata
yearmon h0 h1 name
1 200602 1 4 abvol
2 200603 2 3 abvol
3 199106 3 2 accr
4 199107 4 1 accr
I want to compute various functions (min, max, mean, stdev, kurtosis, etc.)
over the groups defined in the "name" variable using the "by" function.
On some data sets I can get "mean" to work fine but not the others.
On the example above, I get the following results using "mean"
by(as.data.frame(tempdata[,1]), tempdata$name, mean)
> by(as.data.frame(tempdata[, 1]), tempdata$name, mean)
tempdata$name:abvol
[1] NA
-----------------------------------------------------------
tempdata$name:accr
[1] NA
On the example above, I get the following results using "min"
by(as.data.frame(tempdata[,1]), tempdata$name, mean)
> by(as.data.frame(tempdata[, 1]), as.factor(tempdata$name),
min)
Problem in NextMethod(.Generic): Can't find the generic
function "FUN"
Use traceback() to see the call stack
Would someone please explain to me how I can make these work?
I'm running Splus 7.0 on Windows 2000.
Thanks!
Matt
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