[R] help with data layout
Stephen Tucker
brown_emu at yahoo.com
Thu Jul 17 18:29:15 CEST 2008
Hi, hope this will help:
txt <- "Col1, Col2
A, 3
, 2
, 3
B, 4
, 5
, 4
C, 1
, 4
, 3"
## read data
dat <- read.csv(textConnection(txt),na.string="")
## fill in empty cells with correct category
dat$Col1[] <-
Reduce(function(x,y) c(x,ifelse(is.na(y),tail(x,1),y)),dat$Col1)
## calculate mean and standard deviation
mat <- t(sapply(split(dat$Col2,f=dat$Col1),function(X)
c(mean=mean(X),sd=sd(X))))
## look at results (stored in a matrix)
> print(mat)
mean sd
A 2.666667 0.5773503
B 4.333333 0.5773503
C 2.666667 1.5275252
----- Original Message ----
From: Iain Gallagher <iaingallagher at btopenworld.com>
To: r-help at stat.math.ethz.ch
Sent: Thursday, July 17, 2008 8:50:42 AM
Subject: [R] help with data layout
Hello list
I have been given some Excel sheets with data laid like this:
Col1 Col2
A 3
2
3
B 4
5
4
C 1
4
3
I was hoping to import this into R as a csv and then get the mean and SD for each letter in column 1.
Could someone give me some guidance on best to approach this?
Thanks
Iain
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