How to select words from corpus for TermDocumentMatrix creation in tm

Asked Apr 29 '16 at 07:45

Active Apr 29 '16 at 08:15

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I want to retain only pattern words (i.e gene names which I have specified) from each document of my corpus to generate the dtm. I do not want to pre-process the documents before corpus creation. I want to select and retain the gene names from the corpus only. I have used a custom function to keep only the terms in "pattern" and remove everything else (How to select only a subset of corpus terms for TermDocumentMatrix creation in tm). Here are my codes.

    library(tm)
    library(Rstem)
    library(RTextTools)

    docs <- Corpus(DirSource(path of the directory))
    # Custom function to keep only the terms in "pattern" and remove everything else
    f <- content_transformer(function(x, pattern)regmatches(x, gregexpr(pattern, x, perl=TRUE, ignore.case=TRUE)))
    # The pattern i want to search for
    gene = "IL1|IL2|IL3|IL4|IL5|IL6|IL7|IL8|IL9|IL10|TNF|TGF|AP2|OLR1|OLR2"

    docs <- tm_map(docs, f, gene)[[1]]

However, I get the error

" Error in UseMethod("content", x) :no applicable method for 'content' applied to an object of class "character" "

edited May 23 '17 at 12:16

Community

asked Apr 29 '16 at 07:45

Sushri

works with the `tm` data set (`data(crude)`), did you try to transform corpus before running FUN? `docs <- tm_map(docs, tm::PlainTextDocument)` – JohnCoene Apr 29 '16 at 09:06
Thanks a lot. Its working now. – Sushri May 02 '16 at 05:54

How to select words from corpus for TermDocumentMatrix creation in tm

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