length of vectors with tapply

Dear All:

I was trying to get the lengths of vectors using "length" in tapply as
follows:

ni<-tapply(data[,2], data[,2], length, na.rm=TRUE)

but it did not work for me. I am not sure what I am doing wrong.

I am not sure if I should use different function.

Here is the data:
============
data<-matrix(c(8,24,0,0,16,32,6,0,16,7,4,4,9,5,8,18,2,0,4,0,8,3,1,5,24,12,2,8,1,8,
1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,2,2,2,2,2,2,2,2,2,2,3,3),30,2)



The answer should be:

ni: 18  ,  10  ,  2


thank you very much
Steven

Dear Steven,

If you remove the parameter:
na.rm=TRUE
then your example seems to work fine for me.  Good luck!

Best wishes,
Mark

Mark Daniel Ward, Ph.D.
Associate Professor and Undergraduate Chair
Department of Statistics
Purdue University
150 North University Street
West Lafayette, IN 47907-2067
mdw at purdue.edu
phone: (765) 496-9563




On 9/9/14, 11:12 PM, Steven Stoline wrote:

Dear All:

I was trying to get the lengths of vectors using "length" in tapply as
follows:

ni<-tapply(data[,2], data[,2], length, na.rm=TRUE)

but it did not work for me. I am not sure what I am doing wrong.

I am not sure if I should use different function.

Here is the data:
============
data<-matrix(c(8,24,0,0,16,32,6,0,16,7,4,4,9,5,8,18,2,0,4,0,
8,3,1,5,24,12,2,8,1,8,
1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,2,2,2,2,2,2,2,2,2,2,3,3),30,2)



The answer should be:

ni: 18  ,  10  ,  2


thank you very much
Steven