Group by grepping for terms in a column with dplyr

Question

I have a dataframe as follows:

Symptom                                          number        

Abdominal pain\n Swallowing probs\n Back issues\n       22
Abdominal pain\n                                        12
Back issues \n Vomiting \n                                 14
Back issues\n                                            5

There is always a \n at the end of each symptom phrase. The symptom phrase itself can literally be anything so I don't want to search for these terms specifically, but rather any term before (or between) \n

I would like to average the number for each symptom so that I end up with:

Symptom                       Avg
Abdominal pain                 17
Swallowing probs               22
Back issues                    20.5
Vomiting                       14

I don't know how to group by the individual terms with dplyr. I have tried

SypmAvg<- df %>% group_by(grepl("(?\\n.*\\n)|($.*?\\n)",df$Symptom)%>% summarise(mean=mean(number)

but it just crashes my computer so I don't even get to see the error. Can anyone help? Is it just a regex issue or is there a better way to do this?


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| R   | regex   | dplyr   2017-01-06 11:01 2 Answers

Answers ( 2 )

  1. 2017-01-06 11:01

    We can use cSplit

    library(splitstackshape)
    cSplit(df, "Symptom", "\\n", "long")[, .(Avg = mean(number)), .(Symptom)]
    
  2. 2017-01-06 16:01
    library(dplyr)
    df1 = df %>% group_by(id) %>% mutate(new_col = strsplit(Symptom, "\n")) %>% unnest()
    
    df1 %>% group_by(trimws(new_col)) %>% summarise( ans = mean(number))
    
    # new_col   ans
    # 1   Abdominal pain 17.00000
    # 2      Back issues 13.66667
    # 3 Swallowing probs 22.00000
    # 4         Vomiting 14.00000
    
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