On 09/19/2011 04:46 PM, Henri-Paul Indiogine wrote:
Greetings!
I am using the R library RQDA to assign certain codes to paragraphs of
documents in a collection. Several paragraphs are assigned more than
1 code. E.g. often the codes "poverty" and "education" will be
assigned to the same paragraph. Often also "math" and "career" will
be given to the same paragraphs. Other codes are never given to the
same paragraphs.
I would like to calculate the relationship or "closeness" of certain
codes. RQDA will generate a cross-codes table. It has the form of an
upper triangular matrix where the upper triangle has the number of
cross occurrences of 2 codes at their intersection. The lower
triangle is filled with NA. The diagonal simply has the number of
occurrences of the codes by themselves.
The row names are the names of the codes and the column names are the
IDs of the codes. E.g.
1 2 3 4
code1 3 0 2 1
code2 NA 4 1 0
code3 NA NA 2 0
code4 NA NA NA 3
We can see that code1 is associated 2 out of 3 times with code3.
Code2 is present 1 out of 4 times with code3. Code2 is never assigned
to the same paragraph as Code1 and Code4 are, and so on.
I am trying to understand how to create some sort of graph or diagram
to represent this. Should I use a cluster diagram or a network graph?
Also, what sort of R code could I use?
Hi Henri,
The intersectDiagram function in the plotrix package displays the
intersections of sets as rectangles with widths (and areas) proportional
to the number of members of each set intersection. This may be a way for
you to represent your codes. For your example, you could proceed like
this. Create a file ("hp.csv")containing the following:
paragraph,attribute
p1,code1
p1,code3
p2,code1
p2,code3
p3,code1
p3,code4
p4,code2
p5,code2
p6,code2
p7,code2
p7,code3
p8,code3
p9,code3
p10,code4
p11,code4
p12,code4
then:
library(plotrix)
hp<-read.csv("hp.csv")
intersectDiagram(hp,main="Combinations of codes")
There are other ways to represent your original data that
intersectDiagram will read in that you might like to try.
Jim
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