Converting units (cm to in) for some observations in R-CodePudding

I have a data set where some observations are in cm and some are in inches. I need to convert all of the values to inches. The number is in one column and the unit is in another.

height   unit
12.0       in
15.0       in
45.0       cm
13.0       in
52.0       cm
61.0       cm

and basically I just want all of them in inches. Should I use some kind of if statement, or subset the data where the unit is cm? Thanks for any help.

CodePudding user response：

In R base 1:

> dat$height[dat$unit=="cm"] <- dat$height[dat$unit=="cm"]*0.393701
> dat$unit <- "in"
> dat
    height unit
1 12.00000   in
2 15.00000   in
3 17.71654   in
4 13.00000   in
5 20.47245   in
6 24.01576   in

R Base 2:

dat$height <- with(dat, ifelse(unit == "cm", height * 0.393701, height))

More readable with dplyr:

library(dplyr)
dat <- dat %>% 
    mutate(height = if_else(unit == "cm", height * 0.393701, height))

CodePudding user response：

dt <- data.table(
  height = c(12.0, 15.0, 45.0, 13.0, 52.0, 61.0),
  unit = c("in", "in", "cm", "in", "cm", "cm")
)

dt[, height_in_inches := ifelse(unit == "cm", height / 2.54, height)]

dt
#    height unit height_in_inches
# 1:     12   in           12.000
# 2:     15   in           15.000
# 3:     45   cm           17.717
# 4:     13   in           13.000
# 5:     52   cm           20.472
# 6:     61   cm           24.016