On 12/2/2010 3:52 PM, David Winsemius wrote:
On Dec 2, 2010, at 5:58 AM, Karl Brand wrote:
On 12/2/2010 11:36 AM, David Winsemius wrote:
On Dec 2, 2010, at 5:22 AM, Karl Brand wrote:
Cheers Bill.
Inserting earlier debris:
I don't understand why i get this error message when attempting to
use merge() -
> temp <- merge(x, y[,17, drop=FALSE], by=rownames, sort=FALSE)
Error in as.vector(x, mode) :
cannot coerce type 'closure' to vector of type 'any'
Try
by="rownames"
instead of
by=rownames
At this point I think Bill should have suggested by="row.names" since
that is the correct argument to merge() when asking for a rownames
match, and you appear to have found that by experimentation since you
didn't seem to have read the help page.
You got me halfway, since:
> temp <- merge(x=x, y=y[,17, drop=FALSE], by="rownames", sort=FALSE)
Error in fix.by(by.x, x) : 'by' must specify valid column(s)
but, using "row.names" instead of "rownames", like:
> temp <- merge(x=x, y=y[,17, drop=FALSE], by="row.names", sort=FALSE)
works (but adds a column "Row.names").
OK. It added a column what's the problem? The help(merge) pages says:
"If the matching involved row names, an extra character column called
Row.names is added at the left, and in all cases the result has
‘automatic’ row names."
Which seems some what counter intuitive to me since i am feeding in
two matrices to the merge function, which i understand have
'rownames', not 'row.names' as data frames have, right?
Although the
output of merge() is a data frame...
Right. The merge function takes either dataframes or things which can be
coerced to dataframes as arguments and returns a dataframe. That is
exactly what the help(merge) page states outright (in many places). Just
because your arguments were matrices doesn't mean the returned object
should be one. Had you wanted it to be an "augmented" data.matrix with
rownames as before, you could gotten that after merge by:
?data.matrix
temp2 <- datamatrix(temp[-1])
rownames(temp2) <- temp$Row.names
(Or by the rather nice manipulations that you described using rownames
as indices.)
I think I understand the "problem" now .... that you were expecting
merge() to behave differently than is documented.
Cheers David,
You nailed it- closer attention to the help page would defiently have
saved us time.
No less, thanks a lot for highlighting this, and also for the merge()
clarifications.
And insight into what physicists have to deaal with :)
cheers,
Karl
--
Karl Brand <k.br...@erasmusmc.nl>
Department of Genetics
Erasmus MC
Dr Molewaterplein 50
3015 GE Rotterdam
P +31 (0)10 704 3211 | F +31 (0)10 704 4743 | M +31 (0)642 777 268
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