On Oct 18, 2011, at 2:53 PM, Dennis Murphy wrote:
Prompted by David's xtabs() suggestion, one way to do what I think the
OP wants is to
* define day and unit as factors whose levels comprise the full range
of desired values;
* use xtabs();
* return the result as a data frame.
Something like
x <- data.frame( day = factor(rep(c(4, 6), each = 8), levels = 4:6),
unit = factor(c(1:8, seq(2,16,2)), levels = 1:16),
value = floor(rnorm(16,25,10)) )
as.data.frame(with(x, xtabs(value ~ unit + day)))
Oh, ... sometimes I'm "slow". Dennis' code has it's virtues, but
sometimes people want to avoid factors. Could also create a zero-
numeric-matrix to fill the interiors and rbind to the analysis matrix
just in the data= input to xtabs:
zeroes <- cbind(day =seq( min(day), max(day), by=1),
unit=seq(min(unit), max(unit), by=1),
value=0) # ignore warning
xtabs(value~day+unit, data=rbind(x, zeroes) )
unit
day 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16
4 25 34 3 25 38 18 19 33 0 0 0 0 0 0 0 0
5 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0
6 0 22 0 42 0 37 0 4 0 12 0 31 0 17 0 28
--
David.
HTH,
Dennis
On Tue, Oct 18, 2011 at 11:33 AM, David Winsemius
<dwinsem...@comcast.net> wrote:
On Oct 18, 2011, at 2:24 PM, Sarah Goslee wrote:
Hi Jonny,
On Tue, Oct 18, 2011 at 1:02 PM, Jonny Armstrong
<jonny5armstr...@gmail.com> wrote:
I am analyzing the spatial distribution of fish in a stream. The
stream
is
divided into equally sized units, and the number of fish in each
unit is
counted. My problem is that my dataset is missing rows where the
count in
a
unit equals zero. I need to create zero data for the missing units.
For example:
day<-(c(rep(4,8),rep(6,8)))
unit<-c(seq(1,8,1),seq(2,16,2))
value<-floor(rnorm(16,25,10))
x<-cbind(day,unit,value)
Thanks for the actual reproducible example.
x
day unit value
[1,] 4 1 19
[2,] 4 2 15
[3,] 4 3 16
[4,] 4 4 20
[5,] 4 5 17
[6,] 4 6 15
[7,] 4 7 14
[8,] 4 8 29
[9,] 6 2 18
[10,] 6 4 22
[11,] 6 6 27
[12,] 6 8 16
[13,] 6 10 45
[14,] 6 12 36
[15,] 6 14 34
[16,] 6 16 13
Lets say the stream has 16 units. For each day, I want to fill in
rows
for
any missing units (e.g., units 9-16 for day 4, the odd numbered
units on
day
6) with values of zero.
I could not figure out what you wanted precisely. If "day" is the row
designator, and you want values by 'unit' and 'day' with zeros for
the
missing, then that is exactly what `xtab` delivers:
xtabs(value ~ day+unit, data=x)
unit
day 1 2 3 4 5 6 7 8 10 12 14 16
4 25 34 3 25 38 18 19 33 0 0 0 0
6 0 22 0 42 0 37 0 4 12 31 17 28
You cannot get much more concise than that.
--
david.
Here's one option, though it may not be terribly concise:
all.samples <- expand.grid(day=unique(x[,"day"]), unit=1:16)
all.samples <- all.samples[order(all.samples[,"day"],
all.samples[,"unit"]),]
x.final <- merge(x, all.samples, all.y=TRUE)
x.final[is.na(x.final[,"value"]), "value"] <- 0
Sarah
Does anyone know a relatively concise way to do this?
Thank you.
[[alternative HTML version deleted]]
--
Sarah Goslee
http://www.functionaldiversity.org
______________________________________________
R-help@r-project.org mailing list
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PLEASE do read the posting guide
http://www.R-project.org/posting-guide.html
and provide commented, minimal, self-contained, reproducible code.
David Winsemius, MD
West Hartford, CT
______________________________________________
R-help@r-project.org mailing list
https://stat.ethz.ch/mailman/listinfo/r-help
PLEASE do read the posting guide http://www.R-project.org/posting-guide.html
and provide commented, minimal, self-contained, reproducible code.
David Winsemius, MD
West Hartford, CT
______________________________________________
R-help@r-project.org mailing list
https://stat.ethz.ch/mailman/listinfo/r-help
PLEASE do read the posting guide http://www.R-project.org/posting-guide.html
and provide commented, minimal, self-contained, reproducible code.
