CODEWITHSUNDEEP
rsubstrstring-length
Pedro Campos
Pedro Campos

Reputation: 51

Getting last character/number of data frame column

I'm trying to get the last character or number of a series of symbols on data frame so I can filter some categories after. But I'm not getting the expected result.

names = as.character(c("ABC Co","DEF Co","XYZ Co")) 
code = as.character(c("ABCN1","DEFMO2","XYZIOIP4")) #variable length
my_df = as.data.frame(cbind(names,code))

First Approach:

my_df[,3] = substr(my_df[,2],length(my_df[,2]),length(my_df[,2]))

What I expected to receive was: c("1","2","4")

What I am really receiving is : c("C","F","Z")

Then, I realized that length(my_df[,2]) is the number of rows of my data frame, and not the length of each cell. So, I decided to create this loop:

for (i in length(nrow(my_df))){
  my_df[i,3] = substr(my_df[i,2],length(my_df[i,2]),length(my_df[i,2]))
}

What I expected to receive was: c("1","2","4")

What I am really receiving is : c("A","F","Z")

So then I tried:

for (i in length(nrow(my_df))){
  my_df[i,3] = substr(my_df[i,2],-1,-1)
}

What I expected to receive was: c("1","2","4")

What I am really receiving is : c("","F","Z")

Not getting any luck, any thoughts of what am I missing? Thank you very much!

Upvotes: 1

Views: 1783

Answers (4)

akrun
akrun

Reputation: 887028

We can use sub

 sub(".*(\\d+$)", "\\1", my_df$code)

Upvotes: 0

nurandi
nurandi

Reputation: 1618

You can use substr:

my_df$last_char <- substr(code, nchar(code), nchar(code))
# or my_df$last_char <- substr(my_df$code, nchar(my_df$code), nchar(my_df$code))

Output

my_df

#   names     code last_char
# 1 ABC Co    ABCN1         1
# 2 DEF Co   DEFMO2         2
# 3 XYZ Co XYZIOIP4         4

Upvotes: 0

r2evans
r2evans

Reputation: 160417

length is a vector (or list) property, whereas in substr you probably need a string property. Base R's nchar works.

my_df = as.data.frame(cbind(names, code), stringsAsFactors = FALSE)
substr(my_df[,2], nchar(my_df[,2]), nchar(my_df[,2]))
# [1] "1" "2" "4"

(I added stringsAsFactors = FALSE, otherwise you'll need to add as.character.)

Upvotes: 1

Chris Ruehlemann
Chris Ruehlemann

Reputation: 21400

If the last character is always a number you can do:

library(stringr)
str_extract(my_df$code, "\\d$")
[1] "1" "2" "4"

If the last character can be anything you can do this:

str_extract(my_df$code, ".$")

Upvotes: 1

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