stringr split column by alpha and numeric

Question

I can only use stringer/ regular expression, I am working in r

I have a csv I have downloaded called mpg2,and a subset of this containing only Mercedes Benz makes. What I am trying to do is split the model into alpha and numeric so I can plot them. for example, a mercedes C300 would need to be split into C and 300, or GLS500 into GLS and 550.

so now I have all of the model numbers, now I want to split between letters and numbers.

I have tried

mercedes<- subset(mpg2, make=="Mercedes-Benz")
str_split(mercedes$model, "[0:9]")

but this doesn't do what I want it to and I have played with n= and that doesn't work either. then I have

MB$modelnumber<-as.numeric(gsub("([0-9]+).*$", "\\1", mercedes$model))

Which makes a column of only numbers, I can't get the letters to work. If I need to upload my specific dataset let me know, I just have to figure out how to do that.

But I need to basically split "XYZ123" into its alpha and numeric parts and put them in 2 separate columns.

It's better if you give example of real data! is the string to be split always going to be "XYZ123" format? Or is there possibility of numbers interspersed in the alphanumeric? — CHP, Apr 14 '14 at 04:31
is there a way I can send the dataset maybe..? some examples are SL550, C300, 500SL, 380SL etc. — hk47, Apr 14 '14 at 04:43

score 2 · Answer 1 · answered Apr 14 '14 at 04:29

2

something like this :

x <- "XYZ123"
x <- gsub("([0-9]+)",",\\1",x)
strsplit(x,",")

i ve replaced the original group of numbers by ,group of numbers. so that i can do a split on ot easily.

answered Apr 14 '14 at 04:29

aelor

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okay so how would I modify the now split columns into something I can plot using ggplot? as in how do I put these split columns back into the dataset – hk47 Apr 14 '14 at 04:44
thats a different question overall, but i would suggest puushing the values into a 2d array. – aelor Apr 14 '14 at 04:45
do you want me to ask it separately..? – hk47 Apr 14 '14 at 04:47
@hk47, there is no need to ask it separately. Instead, a better option would be to edit your question with a sample of input and desired output so that those who are taking the time to help you answer your question are able to give the most helpful answers. – A5C1D2H2I1M1N2O1R2T1 Apr 14 '14 at 06:54

A5C1D2H2I1M1N2O1R2T1 · Answer 2 · 2014-04-14T06:41:38.910

You can use something like this:

SplitMe <- function(string, alphaFirst = TRUE) {
  Pattern <- ifelse(isTRUE(alphaFirst), "(?<=[a-zA-Z])(?=[0-9])", "(?<=[0-9])(?=[a-zA-Z])")
  strsplit(string, split = Pattern, perl = T)
}

String <- c("C300", "GLS500", "XYZ123")
SplitMe(String)
# [[1]]
# [1] "C"   "300"
# 
# [[2]]
# [1] "GLS" "500"
# 
# [[3]]
# [1] "XYZ" "123"

To get the output as a two column matrix, just use do.call(rbind, ...):

do.call(rbind, SplitMe(String))
#      [,1]  [,2] 
# [1,] "C"   "300"
# [2,] "GLS" "500"
# [3,] "XYZ" "123"

The above is just a convenience function that I have saved for the following scenarios:

strsplit(String, split = "(?<=[a-zA-Z])(?=[0-9])", perl = T)

and

strsplit(String, split = "(?<=[0-9])(?=[a-zA-Z])", perl = T)

This function won't change a GLS500 into a GLS550 though.

stringr split column by alpha and numeric

2 Answers2