[R] Creating a co-occurence matrix

2003-07-01 Thread Greg Blevins 
Hello R experts,

I have a data.frame which has a series of 30 variables that are each coded
1,0--1
if a behavior is engaged in, 0 otherwise.

The data.frame looks like this:

var1 var2 ...var30
Respondent 1
Respondent 2
etc

I would like to create a matrix (or at least a half-matrix) as follows:

  var1  var2 ...var30
var1
var 2
.
.
var 30

where the number at each intersection is the number of people who engaged in
both behaviors.  I could run a whole bunch of tables and input the data by
hand into a new matrix, but I was wondering if there is a way to do this via
a program/function (I looked at daisy, but concluded this function would
not handle this).

Any help would be appreciated!

Greg Blevins
The Market Solutions Group

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RE: [R] Creating a co-occurence matrix

2003-07-01 Thread Liaw, Andy 
 From: Greg Blevins [mailto:[EMAIL PROTECTED] 
 
 Hello R experts,
 
 I have a data.frame which has a series of 30 variables that 
 are each coded 1,0--1 if a behavior is engaged in, 0 otherwise.
 
 The data.frame looks like this:
 
 var1 var2 ...var30
 Respondent 1
 Respondent 2
 etc
 
 I would like to create a matrix (or at least a half-matrix) 
 as follows:
 
   var1  var2 ...var30
 var1
 var 2
 .
 .
 var 30
 
 where the number at each intersection is the number of people 
 who engaged in both behaviors.  I could run a whole bunch of 
 tables and input the data by hand into a new matrix, but I 
 was wondering if there is a way to do this via a 
 program/function (I looked at daisy, but concluded this 
 function would not handle this).

If I understood you correctly, the cross product of the matrix should do it.
If your data frame is named df, then you can do

  answer - crossprod(data.matrix(df))

Hth,
Andy

 
 Any help would be appreciated!
 
 Greg Blevins
 The Market Solutions Group
 
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 [EMAIL PROTECTED] mailing list 
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