[FIXED] How to replace a range of int values with string character in R

Issue

I would like to replace a range of integer values with a string character based on conditions.

For example, I have a dataframe

    Gender   Grade   Indus 
  1      1     610     15    
  2      1     110     29     
  3      2     210     32     
  4      1     250     20   
  5      2     420     37   
  6      2     430     19
  7      1     450     25

I would like to replace the values in 'Grade' column with some string character based on conditions as follows:

prima =c(110,210:250,610)
secon =c(420,440:460)
vocat =c(430,470)

If the number in 'Grade' falls in prima, for example, if Grade==610, I would like to change the number to a word 'Primary'.

I have tried by using...

mydf$Grade[mydf$Grade == prima] <- "Primary"
mydf$Grade[mydf$Grade == secon] <- "Secondary"
mydf$Grade[mydf$Grade == vocat] <- "Vocational"

but it did not work. It didn't return error, but only a very very few values changed to 'Primary' or 'Secondary', leaving a bunch of other numbers unchanged.

I have also tried...

for (i in mydf$Grade) {
    if (i %in% prima) mydf$Grade <- "Primary"
    else if (i %in% secon) mydf$Grade <- "Secondary"
    else if (I %in% vocat) mydf$Grade <- "Vocational"
}

which also did not work. All the values in 'Grade' turned to 'Primary' instead. These two methods I have tried with the real data where I also have to loop over 10 years.

I don't know what I did wrong. I have tried these method and it worked when I wanted to replace with NaN; however, it does not work when I wanted to replace with other integers or string characters. Any advices would be very much appreciated.

Solution

== does element-wise comparison. Since we want to compare multiple elements here use %in%

mydf$Grade[mydf$Grade %in% prima] <- "Primary"
mydf$Grade[mydf$Grade %in% secon] <- "Secondary"
mydf$Grade[mydf$Grade %in% vocat] <- "Vocational"

Or use dplyr::case_when

library(dplyr)
mydf %>%
  mutate(Grade = case_when(Grade %in% prima ~ "Primary", 
                           Grade %in% secon ~ "Secondary", 
                           Grade %in% vocat ~ "Vocational"))


#  Gender      Grade Indus
#1      1    Primary    15
#2      1    Primary    29
#3      2    Primary    32
#4      1    Primary    20
#5      2  Secondary    37
#6      2 Vocational    19
#7      1  Secondary    25

data

mydf <- structure(list(Gender = c(1L, 1L, 2L, 1L, 2L, 2L, 1L), Grade = c(610L, 
110L, 210L, 250L, 420L, 430L, 450L), Indus = c(15L, 29L, 32L, 
20L, 37L, 19L, 25L)), class = "data.frame", row.names = c(NA, -7L))

Answered By - Ronak Shah

Answer Checked By - Dawn Plyler (PHPFixing Volunteer)