在向量中计数单词

Question

Currently I have enrolled in a R course and one of the practice exercises is building a R program to count words in a string. We cannot use the function table but must return an output of the most popular word in a string using conventional means. ie The fox jumped over the cone and the... So the program would have to return "the" as it is the most popular phrase.

So far I have the following:

string_read<- function(phrase) {

  phrase <- strsplit(phrase, " ")[[1]]
  for (i in 1:length(phrase)){
    phrase.freq <- ....
#if Word already exists then increase counter by 1

      }

I've hit a road block however as I'm not sure how to increase the counter for specific words. Can anyone give me a pointer in the right direction? My psuedo code would be something like: "For every word that is looped through, increase wordIndex by 1. If word has already occured before, increase wordIndex counter."

Answer 1

You started off correctly by splitting the string into words, then we loop over each word using sapply and sum the similar words in the vector. I have used tolower assuming this operation is not case sensitive.

string_read<- function(phrase) {
   temp = tolower(unlist(strsplit(phase, " ")))
   which.max(sapply(temp, function(x) sum(x == temp)))
}

phrase <- "The fox jumped over the cone and the"

string_read(phrase)
#the 
#  1 

This returns output as the word and its index position which is 1 in this case. If you just want the word with maximum count , you can change the last line to

temp[which.max(sapply(temp, function(x) sum(x == temp)))]

Answer 2

We can do this with str_extract

library(stringr)
string_read<- function(str1) {
  temp <- tolower(unlist(str_extract_all(str1, "\\w+")))
  which.max(sapply(temp, function(x) sum(x == temp)))
}

phrase <- "The fox jumped over the cone and the"
string_read(phrase)
#the 
#  1 
phrase2 <- "The fox jumped over the cone and the fox, fox, fox, fox, fox"
string_read(phrase)
#fox 
# 2