R help - Mar 2008 - Solution to: Error "... x must be atomic" when using lsa (latent semantic analysis) package

In case someone else runs into this, I found the problem, it was related to
having some zero-length text files.  Make sure you have valid (non-empty)
data files for loading into the document-term matrix.

Alex

---------- Forwarded message ----------
From: Alex McKenzie <ahmckenzie@gmail.com>
Date: Mar 25, 2008 2:07 AM
Subject: Error "... x must be atomic" when using lsa (latent semantic
analysis) package
To: r-help@r-project.org


Hello,

I'm trying to use the "lsa" (latent semantic analysis) package,
and running
into a problem that seems to be related to the number of documents being
processed.  Here's the code I'm running (after loading the lsa and rstem
packages), and the error message:
> SnippetsPath <- "c:\\OED\\AuditExplain\\"  # path where to
find text
snippets
> data(stopwords_en)
> tdm <- textmatrix(SnippetsPath, stopwords=stopwords_en)
I get this error message with ~ 280 documents:  "Error in sort(
unique.default(x), na.last = TRUE) : 'x' must be atomic"

The error won't occur if I reduce the number of documents (say to 220, for
instance).  I'm not clear if this is memory/capacity issue or something
else.
A traceback returns the following, but interpreting this result is outside
of my league ;-)  Any idea of what could be the problem?  I greatly
appreciate your advice.
> traceback()
10: stop("'x' must be atomic")
9: sort(unique.default(x), na.last = TRUE)
8: factor(a, exclude = exclude)
7: table(txt)
6: inherits(x, "factor")
5: is.factor(x)
4: sort(table(txt), decreasing = TRUE)
3: FUN(X[[238]], ...)
2: lapply(dir(mydir, full.names = TRUE), textvector, stemming, language,
       minWordLength, minDocFreq, stopwords, vocabulary)
1: textmatrix(SnippetsPath, stopwords = stopwords_en)

Alex

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