根据一列中的条件和另一列中的值在 r 中生成一个新变量

Question

I have a dataframe containing data on subject, height, and height unit

subject <- c(1,2,3,4)
height <- c(100, 90, 56, 64)
height_unit <- c("cm", "cm", "inches", "inches")
complete_file <- data.frame(subject, height, height_unit)

Essentially, what I want to do is multiply the height column by 2.54 any time that the height_unit is equal to inches. Here is what I have tried so far:

vital_signs_clean <- vital_signs_clean %>%
     group_by(subject_id) %>%
     mutate(height = if(n_distinct(Height_Units == "inches", na.rm = TRUE) == 1), *2.54)

For this, I received an error stating "unexpected 'else'" in the code. Is this the best way to go about it or are there better recommendations?

Answer 1

This should do the trick:

library(dplyr)
complete_file %>% 
  mutate(height = ifelse(height_unit == "inches", height * 2.54, height))

Output:

  subject height height_unit
1       1 100.00          cm
2       2  90.00          cm
3       3 142.24      inches
4       4 162.56      inches