Count values separated by a comma in a character string

Question

I have this example data

d<-"30,3"
class(d)

I have this character objects in one column in my work data frame and I need to be able to identify how many numbers it has.

I have tried to use length(d), but it says 1

After looking for solution here I have tried

eval(parse(text='d'))
as.numeric(d)
as.vector.character(d)

But it still doesn't work.

Any straightforward approach to solve this problem?

Answer 1

These two approaches are each short, work on vectors of strings, do not involve the expense of explicitly constructing the split string and do not use any packages. Here d is a vector of strings such as d <- c("1,2,3", "5,2") :

1) count.fields

count.fields(textConnection(d), sep = ",")

2) gregexpr

lengths(gregexpr(",", d)) + 1

Answer 2

You could use scan.

 v1 <- scan(text=d, sep=',', what=numeric(), quiet=TRUE)
 v1
 #[1] 30  3

Or using stri_split from stringi. This should take both character and factor class without converting explicitly to character using as.character

library(stringi)
v2 <- as.numeric(unlist(stri_split(d,fixed=',')))
v2
#[1] 30  3

You can do the count using base R by

length(v1)
#[1] 2

Or

nchar(gsub('[^,]', '', d))+1
#[1] 2

Visualize the regex

 [^,]

Debuggex Demo

Update

If d is a column in a dataset df and want to subset rows with number of digits equals 2

  d<-c("30,3,5","30,5") 
  df <- data.frame(d,stringsAsFactors=FALSE)
  df[nchar(gsub('[^,]', '',df$d))+1==2,,drop=FALSE]
  #    d
  #2 30,5

Just to test

  df[nchar(gsub('[^,]', '',df$d))+1==10,,drop=FALSE]
  #[1] d
  #<0 rows> (or 0-length row.names)