Why does the ngrams() function give distinct bigrams?

Question

I am writing an R script and am using library(ngram).

Suppose I have a string,

"good qualiti dog food bought sever vital can dog food product found good qualiti product look like stew process meat smell better labrador finicki appreci product better"

and want to find bi-grams.

The ngram library is giving me bi-grams as follows:

"appreci product" "process meat" "food product" "food bought" "qualiti dog" "product found" "product look" "look like" "like stew" "good qualiti" "labrador finicki" "bought sever" "qualiti product" "better labrador" "dog food" "smell better" "vital can" "meat smell" "found good" "sever vital" "stew process" "can dog" "finicki appreci" "product better"

As the sentence contains "dog food" two times, I want this bi-gram two times. But I am getting it once!

Is there an option in thengram library or any other library that gives all the bi-grams of my sentence in R?

Answer 1

The development version of ngram has a get.phrasetable method:

devtools::install_github("wrathematics/ngram")
library(ngram)

text <- "good qualiti dog food bought sever vital can dog food product found good qualiti product look like stew process meat smell better labrador finicki appreci product better"

ng <- ngram(text)
head(get.phrasetable(ng))
#            ngrams freq       prop
# 1    good qualiti    2 0.07692308
# 2        dog food    2 0.07692308
# 3 appreci product    1 0.03846154
# 4    process meat    1 0.03846154
# 5    food product    1 0.03846154
# 6     food bought    1 0.03846154

In addition, you can use the print() method and specify output == "full". That is:

print(ng, output = "full")

# NOTE: more output not shown...
better labrador | 1 
finicki {1} | 

dog food | 2 
product {1} | bought {1} 
# NOTE: more output not shown...