R Sum numbers within string - r

Question

I have a question:
I have a dataset like this simple example:
df<-data.frame(ID=c("A","B","C","D"),
Score=c("15","16/18/19+2/6","3/+2","19/18/14"))
I want to end up with a dataset that has split the score numbers. I have a problem with the /+2 part. when it says "3/+2"it actually means: "3/3+2" which would finally give "3/5". So what I would like some help with, is to end up with a dataset like this:
ID Score
A 15
B 16/18/19/21/6
C 3/5
D 19/18/14
I already found out that I can then seperate the score by
df<-df %>%
mutate(Score = strsplit(as.character(ID), "/")) %>%
unnest(Score)
But I don't know how I can let the numbers duplicate and then sum when /+ occurs, could someone help me?

Answer 1

It could be probably solved in a more elegant way, but here is one possibility:
df %>%
mutate(Score = strsplit(as.character(Score), "/")) %>%
unnest() %>%
rowwise() %>%
mutate(Score = eval(parse(text = paste0(Score)))) %>%
group_by(ID) %>%
mutate(Score = paste0(Score, collapse = "/")) %>%
distinct()
ID Score
<fct> <chr>
1 A 15
2 B 16/18/21/6
3 C 3/5
4 D 19/18/14
Sample data:
df <- data.frame(ID=c("A","B","C","D"),
Score=c("15","16/18/19+2/6","3/3+2","19/18/14"))
It splits "Score" based on /, converts characters to expression by parse() and then transforms it back.
Using the data you provided and the pattern from #A. Suliman:
df %>%
mutate(Score = strsplit(gsub("(\\d+)/*\\+(\\d+)","\\1/\\1+\\2", Score), "/")) %>%
unnest() %>%
rowwise() %>%
mutate(Score = eval(parse(text = paste0(Score)))) %>%
group_by(ID) %>%
mutate(Score = paste0(Score, collapse = "/")) %>%
distinct()
ID Score
<fct> <chr>
1 A 15
2 B 16/18/19/21/6
3 C 3/5
4 D 19/18/14

Answer 2

We can use gsubfn to do this in a compact way
library(gsubfn)
library(tidyverse)
df %>%
mutate(Score = gsubfn("\\d+\\+\\d+", ~ eval(parse(text = x)), Score))
# ID Score
#1 A 15
#2 B 16/18/21/6
#3 C 3/5
#4 D 19/18/14
data
df <- data.frame(ID=c("A","B","C","D"),
Score=c("15","16/18/19+2/6","3/3+2","19/18/14"), stringsAsFactors = FALSE)

Answer 3

library(dplyr)
library(tidyr) #separate_rows, no need for unnest
df %>% rowwise()%>%
mutate(Score_upd=paste0(sapply(unlist(strsplit(gsub('(\\d+)/*\\+(\\d+)','\\1/\\1+\\2',Score),'/')),
function(x)eval(parse(text = x))),collapse = '/')) %>%
separate_rows(Score_upd,sep = '/')
#short version
df %>% mutate(Score=gsub('(\\d+)/*\\+(\\d+)','\\1/\\1+\\2',Score)) %>%
separate_rows(Score,sep='/') %>% rowwise() %>% mutate(Score=eval(parse(text=Score))) %>%
group_by(ID) %>% summarise(Score=paste0(Score,collapse = '/'))
# A tibble: 4 x 2
ID Score
<fct> <chr>
1 A 15
2 B 16/18/19/21/6
3 C 3/5
4 D 19/18/14
The main idea is using gsub to separate 2+3 correctly, e.g:
gsub('(\\d+)/*\\+(\\d+)','\\1/\\1+\\2','20/8/2+3') #/* means 0 or 1 occurence of / e.g, 19+2 and 3/+2.
[1] "20/8/2/2+3"
Then
valid_str <- gsub('(\\d+)/*\\+(\\d+)','\\1/\\1+\\2','20/8/2+3')
sapply(unlist(strsplit(valid_str,'/')),function(x) eval(parse(text=x)))
20 8 2 2+3
20 8 2 5
#OR
sapply(unlist(strsplit(valid_str,'/')),function(x) sum(as.numeric(unlist(strsplit(x,'\\+')))))
20 8 2 2+3
20 8 2 5