Jan -
Here's one way:
tbl = data.frame(id=c(1,1,1,1,1,2,2,2,2,2),
text=c('this','is','the','first','row','this','is','the','second','row'))
xtabs(~id+text,tbl)
text
id first is row second the this
1 1 1 1 0 1 1
2 0 1 1 1 1 1
It's a bit tricky to automatically get the column headings to
be in the order you want. This comes close:
tbl$text = factor(tbl$text,levels=tbl$text[!duplicated(tbl$text)])
xtabs(~id+text,tbl)
text
id this is the first row second
1 1 1 1 1 1 0
2 1 1 1 0 1 1
Hope this helps.
- Phil Spector
Statistical Computing Facility
Department of Statistics
UC Berkeley
spec...@stat.berkeley.edu
On Tue, 2 Mar 2010, Jan Hornych wrote:
Hi all,
I have a table in database that is very long and when simplified it has only
two columns in it (id, text). id is the row, and text is the column.
Technically the text is a term and and id is the document.
If simplifying this and assuming there is only one occurrence of the term
per the document. I shall be able to convert this into a binary matrix.
Table looks like this...
*ID** **Text*
------------
1 this
1 is
1 the
1 first
1 row
2 this
2 is
2 the
2 send
2 row
...
in R I would like to have it as
*id this is the first second row*
------------------------------------------------
1 1 1 1 1 0 1
2 1 1 1 0 1 1
it would be simpler for me to do this transformation in R as I guess the
language is more handy as the SQL. The table in R have few dozen thousand of
columns and rows as well. I know how to read the data from database, but
just unsure if there is some suitable transformation available.
Thank you
Jan
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