使用单个协变量为主题建模运行stm的问题

Question

I'm trying to run LDA topic modelling analysis with stm but I have problems with my meta data, it seems to work fine but I have a covariate (Age) that is not being read as shown in this example.

I have some tweets (docu column in excel file) with an Age covariate (Young,Old) values..

Here is my data http://www.mediafire.com/file/5eb9qe6gbg22o9i/dada.xlsx/file

library(stm)
library(readxl)
library(quanteda)
library(stringr)
library(tm)


data <-  read_xlsx("C:/dada.xlsx") 

#Remove URL's 
data$docu <- str_replace_all(data$docu, "https://t.co/[a-z,A-Z,0-9]*","")


data$docu <- gsub("@\\w+", " ", data$docu)  # Remove user names (all proper names if you're wise!)

data$docu <- iconv(data$docu, to = "ASCII", sub = " ")  # Convert to basic ASCII text to avoid silly characters
data$docu <- gsub("#\\w+", " ", data$docu)

data$docu <- gsub("http.+ |http.+$", " ", data$docu)  # Remove links

data$docu <- gsub("[[:punct:]]", " ", data$docu)  # Remove punctuation)

data$docu<-  gsub("[\r\n]", "", data$docu)

data$docu <- tolower(data$docu)



#Remove Stopwords. "SMART" is in reference to english stopwords from the SMART information retrieval system and stopwords from other European Languages.
data$docu <- tm::removeWords(x = data$docu, c(stopwords(kind = "SMART")))

data$docu <- gsub(" +", " ", data$docu) # General spaces (should just do all whitespaces no?)

myCorpus <- corpus(data$docu)
docvars(myCorpus, "Age") <- as.factor(data$Age)


processed <- textProcessor(data$docu, metadata = data)

out <- prepDocuments(processed$documents, processed$vocab, processed$meta, lower.thresh = 2)

out$documents
out$meta
levels(out$meta)

First_STM <- stm(documents = out$documents, vocab = out$vocab,
                 K = 4, prevalence =~ Age ,
                 max.em.its = 25, data = out$meta,
                 init.type = "LDA", verbose = FALSE)

As shown in the code I tried to define Age as factor, I think that is not needed because running textProcessor might be enough.. but nevertheless when I run levels(out$meta) I get NULL value so when I then run stm to get the actual topics I get memory allocation error..

Answer 1

You set your metavariable of Age as factor in this line

docvars(myCorpus, "Age") <- as.factor(data$Age)

But you don't use myCorpus further. In the next steps you use your dataframe data for preprocessing. Try to define Age in the dataframe as factor:

data$Age <- factor(data$Age)

and then use it just before here

processed <- textProcessor(data$docu, metadata = data)

out <- prepDocuments(processed$documents, processed$vocab, processed$meta, lower.thresh = 2)

You can then look at the levels like this:

levels(out$meta$Age)

I could not reproduce your memory allocation error though. The stm works fine on my machine (Win 10 Pro, 8GB Ram).