On 05/02/2010 08:26 PM, peterko wrote:
Hi, my data looks this:
id forma program kod obor
rocnik
1 10001 kombinovaná Matematika M1101 matematika 1
2 10002 prezenční Informatika N1801 teoretická informatika 1
3 10002 prezenční Informatika B1801 obecná informatika 3
4 10003 prezenční Informatika M1801 softwarové systémy 5
5 10004 prezenční Informatika B1801 obecná informatika 2
6 10005 kombinovaná Informatika P1801 diskrétní modely a algoritmy 2
stav ukrok
1 zanechal 2002/2003
2 studuje
3 absolvoval 2008/2009
4 absolvoval 2005/2006
5 zanechal 2007/2008
6 zanechal 2004/2005
data$ukrok is a factor
data$rocnik is numeric
I want to create new column (data$z) and in this column have to be
as.numeric(first 4 char of column(data$ukrok))-data$rocnik ---- by the
rows
If ukrok is empty it means 2009.
I know how to do it by cycle FOR , but this is not rigth way. I have too
many observation, and this way is soo slowly.
Know someone how to do it using function TAPPLY ? or another apply function
???
Hi Peterko,
You can do this with vector calculation like this:
# make sure that ukrok is character, not factor
data$ukrok<-as.character(data$ukrok)
# set the empty elements to the correct value
data$ukrok[nchar(data$ukrok)==0]<-"2009/2009"
# split ukrok, unlist it, take only the first component
# convert to numeric and subtract rocnik
data$z<-as.numeric(matrix(unlist(strsplit(data$ukrok,"\")),
ncol=2,byrow=TRUE)[,1])-data$rocnik
Jim
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