[R] Odp: getting data into correct format for summarizing ... reshape, aggregate, or...

Petr PIKAL petr.pikal at precheza.cz
Tue Sep 16 09:25:56 CEST 2008


Another possibility is to use split - sapply construction

sapply(split(df.1[,3],  list(df.1$RiverMile, df.1$constituent)), summary)


Petr Pikal
petr.pikal at precheza.cz
724008364, 581252140, 581252257

r-help-bounces at r-project.org napsal dne 15.09.2008 18:14:40:

> I would like to reformat this data frame into something that I can
> produce some descriptive statistics.  I have been playing around with
> the reshape package and maybe this is not the best way to proceed.  I
> would like to use RiverMile and constituent as the grouping variables
> to get the summary statistics:
> 198a    198b
> mean   mean
> sd       sd
> ...        ...
> etc. for all of these.
> I have tried reshape and aggregate and I am sure that I am missing 
> below is a naive attempt at making a data frame with the columns in
> the correct class-  This can be improved also.  There are NA in the
> real data set, but I didn't know how to randomly intersperse NA in a
> created matrix.  I hope this makes sense.  If it doesn't I will go
> back to the drawing board and try and clarify this.
> value <- rnorm(30)
> RiverMile <- c(rep(215, length.out=10), rep(202, length.out=10),
> rep(198, length.out=10))
> constituent <- c (rep("a", length.out=5), rep("b", length.out=5),
> rep("a", length.out=5), rep("b", length.out=5), rep("a",
> length.out=5), rep("b", length.out=5))
> df <- cbind(as.integer(RiverMile), as.factor(constituent), 
> df.1 <- as.data.frame(df)
> df.1[,"V1"] <- as.integer(df.1[,"V1"])
> df.1[,"V2"] <- as.factor(df.1[,"V2"])
> df.1[,"V3"] <- as.numeric(df.1[,"V3"])
> colnames(df.1) <- c("RiverMile", "constituent", "value")
> -- 
> Stephen Sefick
> Research Scientist
> Southeastern Natural Sciences Academy
> Let's not spend our time and resources thinking about things that are
> so little or so large that all they really do for us is puff us up and
> make us feel like gods. We are mammals, and have not exhausted the
> annoying little problems of being mammals.
>    -K. Mullis
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