How to reclassify dataframe column?

Question

I am working on reclassifying values in one dataframe column and adding those values to another column. The following script attempts to apply a reclassification function to a column and output the values to another column in a dataframe.

a = c(1,2,3,4,5,6,7)

x = data.frame(a)

# Reclassify values in x$a
reclass = function(x){
  # 1 - Spruce/Fir          = 1
  # 2 - Lodgepole Pine      = 1
  # 3 - Ponderosa Pine      = 1
  # 4 - Cottonwood/Willow   = 0
  # 5 - Aspen               = 0
  # 6 - Douglas-fir         = 1
  # 7 - Krummholz           = 1
  if(x == 1) return(1)
  if(x == 2) return(1)
  if(x == 3) return(1)
  if(x == 4) return(0)
  if(x == 5) return(0)
  if(x == 6) return(1)
  if(x == 7) return(1)
}

# Add a new column
x$b = 0

# Apply function on new column
b = lapply(x$b, reclass(x$a))

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The error message:

> b = lapply(x$b, reclass(x$a))
Error in match.fun(FUN) : 
  'reclass(x$a)' is not a function, character or symbol
In addition: Warning message:
In if (x == 1) return(1) :
  the condition has length > 1 and only the first element will be used

---

The intended output should look like the following

a = c(1,2,3,4,5,6,7)
b = c(1,1,1,0,0,1,1)
x = data.frame(a, b)

I have read a seemingly similar question (Reclassify select columns in Data Table), although it appears to be addressing changing the actual class (e.g. numeric) of a column.

How can I take values from one column in a dataframe, apply my reclassification function, and output the values to a new column?

Answer 1

Here, I'd just do (something like):

coniferTypes <- c(1,2,3,6,7)
x$b <- as.integer(x$a %in% coniferTypes)
x
#   a b
# 1 1 1
# 2 2 1
# 3 3 1
# 4 4 0
# 5 5 0
# 6 6 1
# 7 7 1

Answer 2

You could do:

library(dplyr)
mutate(x, b = ifelse(a %in% c(1, 2, 3, 6, 7), 1, 0))