[R] count NAs per week

[arun]

Hi,
Try this:
dattrial<-data.frame(a=c(1,NA,rnorm(4,10)), Week=c(3,3,3,4,4,4))
 aggregate(dattrial$a,list(dattrial$Week),function(x) sum(is.na(x)))
#  Group.1 x
#1       3 1
#2       4 0
#or
 ddply(dattrial,.(Week),summarize, sum(is.na(a))) 
#  Week ..1
#1    3   1
#2    4   0

#or
list1<-split(dattrial,dattrial$Week)
 unlist(lapply(lapply(list1,`[`, 1),function(x) sum(is.na(x))))
#3 4 
#1 0 
A.K. 





----- Original Message -----
From: Tagmarie <Ramgad82 at gmx.net>
To: r-help at r-project.org
Cc: 
Sent: Monday, September 17, 2012 6:03 AM
Subject: [R] count NAs per week

Even though I work with R since a year or so I still struggle with simple
problems. I hope someone can help me with this. Been trying for days and am
a little frustrated now. 

I have a data frame somewhat like the one bellow:

dattrial<-data.frame(a=c(1,NA,rnorm(4,10)), Week=c(3,3,3,4,4,4))

I want to know how many NAs I have in week 3 and in week 4. 



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