[R] POS counting number of verbs

[Elahe chalabi]

Hi all,
I have 16630 Messages in my data frame and I would like to count number of verbs in each message, to do so I have the following code:

> str(tar)
'data.frame': 16630 obs. of  2 variables:
$ Message            : Factor w/ 13412 levels "","'alter database  datafile' needs to be executed",..: 11163 1 9715 10110 9683 11364 12952 2242 7153 6907 ...
$ group                   : Factor w/ 16630 levels "1","2","3","4",..: 1 2 3 4 5 6 7 8 9 10 ...

> tagPOS <-  function(x, ...) {+     s <- as.String(x)+     word_token_annotator <- Maxent_Word_Token_Annotator()+     a2 <- Annotation(1L, "sentence", 1L, nchar(s))+     a2 <- annotate(s, word_token_annotator, a2)+     a3 <- annotate(s, Maxent_POS_Tag_Annotator(), a2)+     a3w <- a3[a3$type == "word"]+     POStags <- unlist(lapply(a3w$features, `[[`, "POS"))+     POStagged <- paste(sprintf("%s/%s", s[a3w], POStags), collapse = " ")+     list(POStagged = POStagged, POStags = POStags)+ }> count_verbs <-function(x) {+     pos_tags <- tagPOS(x)$POStags+     sum(grepl("VB", pos_tags))+ }> library(dplyr)> tar %>% +     group_by(group) %>%+     summarise(num_verbs = count_verbs(Message))
And here is the error I get:Error in summarise_impl(.data, dots) :   Evaluation error: no word token annotations found.

Does anyone know about this error? Thanks for any help.Elahe
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