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I want to recode some numeric values into different numeric values and have had a go using the following code:
survey$KY27PHYc <- revalue(survey$KY27PHY1, c(5=3, 4=2,3=2,2=1,1=1))
I get the following error:
## Error: unexpected '=' in "survey$KY27PHYc <- revalue(survey$KY27PHY1, c(5="
Where am I going wrong?
510
Firstly, we use recode() available in dplyr package (Wickham et al., 2020). Then, we use ifelse() function to recode the categorical data to numeric variables. Last, we learn match() function to rename the character variable to numeric one. The data type of all recoded variables can be converted to each other using as.
Recoding Variables in R Recoding allows you to create new variables and to replace existing values of a variables based on a criterion. This way we can replace the data for every row without any criteria.
Recoding a categorical variable The easiest way is to use revalue() or mapvalues() from the plyr package. This will code M as 1 and F as 2 , and put it in a new column.
You can use recode() directly with factors; it will preserve the existing order of levels while changing the values. Alternatively, you can use recode_factor() , which will change the order of levels to match the order of replacements. See the forcats package for more tools for working with factors and their levels.
We can recode numeric values by using recode or case_when on dplyr 0.7.0.
library(dplyr)
packageVersion("dplyr")
# [1] ‘0.7.0’
x <- 1:10
# With recode function using backquotes as arguments
dplyr::recode(x, `2` = 20L, `4` = 40L)
# [1] 1 20 3 40 5 6 7 8 9 10
# Note: it is necessary to add "L" a numerical value.
dplyr::recode(x, `2` = 20, `4` = 40)
# [1] NA 20 NA 40 NA NA NA NA NA NA
# Warning message:
# Unreplaced values treated as NA as .x is not compatible. Please specify replacements exhaustively or supply .default
# With recode function using characters as arguments
as.numeric(dplyr::recode(as.character(x), "2" = "20", "4" = "40"))
# [1] 1 20 3 40 5 6 7 8 9 10
# With case_when function
dplyr::case_when(
x %in% 2 ~ 20,
x %in% 4 ~ 40,
TRUE ~ as.numeric(x)
)
# [1] 1 20 3 40 5 6 7 8 9 10
This function does not work on numeric vector. If you want to use it, you can do as follows:
x <- 1:10 # your numeric vector
as.numeric(revalue(as.character(x), c("2" = "33", "4" = "88")))
# [1] 1 33 3 88 5 6 7 8 9 10
Try this:
#sample data
set.seed(123); x <- sample(1:5, size = 10, replace = TRUE)
x
# [1] 2 4 3 5 5 1 3 5 3 3
#recode
x <- c(1, 1, 2, 2, 3)[ x ]
x
# [1] 1 2 2 3 3 1 2 3 2 2
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