R中文本中任何一组单词的最大出现次数

Question

给定一组行，我必须找到最多出现的单词（不必是单个单词，也可以是单词集。）

说，我有一个像

这样的文字

string <- "He is john beck. john beck is working as an chemical engineer. Most of the chemical engineers are john beck's friend"

我想要输出，

john beck - 3
chemical engineer - 2

是否有任何功能或包装可以做到这一点？

Answer 1

试试这个：

string <- "He is john beck. john beck is working as an chemical engineer. Most of the chemical engineers are john beck's friend"
library(tau)
library(tm)
tokens <- MC_tokenizer(string) 
tokens <- tokens[tokens != ""]
string_ <- paste(stemCompletion(stemDocument(tokens), tokens), collapse = " ")

## if you want only bi-grams: 
tab <- sort(textcnt(string_, method = "string", n = 2), decreasing = TRUE)
data.frame(Freq = tab[tab > 1])
#                   Freq
# john beck            3
# chemical engineer    2

## if you want uni-, bi- and tri-grams: 
nmin <- 1; nmax <- 3
tab <- sort(do.call(c, lapply(nmin:nmax, function(x) textcnt(string_, method = "string", n = x) )), decreasing = TRUE)
data.frame(Freq = tab[tab > 1])
#                   Freq
# beck                 3
# john                 3
# john beck            3
# chemical             2
# engineer             2
# is                   2
# chemical engineer    2

Answer 2

也可以尝试使用quanteda包：

require(quanteda)
mydfm <- dfm(string, ngrams = 1:2, concatenator = "_", stem = TRUE, verbose = FALSE)
topfeatures(mydfm)
##           beck           john      john_beck         chemic chemical_engin          engin             is 
##              3              3              3              2              2              2              2 
##             an        an_chem            are 
##              1              1              1 

你失去了茎，但这算了“john beck”三次而不是两次（因为没有阻止，“john beck's”将是一个单独的类型。）

虽然它更简单！