Adding new column with conditional values using ifelse

Question

I have a data frame with more than 400.000 observations and I\'m trying to add a column to it which its values depend on another column and sometimes multiple ones.

Answer 1

Same idea but assign it like this instead. No package needed.

M$Size <- ifelse(M$Number <= 50, 'Small', ifelse(M$Number <= 70, 'Medium', 'Big'))

Result:

  Letter Number   Size
1      A      5  Small
2      B    100    Big
3      C     60 Medium

Answer 2

Use cut:

M$Size <- cut(M$Number, breaks = c(-Inf, 50, 70, Inf), 
                        labels = c("small", "medium", "large"))
#   etter Number   Size
#1      A      5  small
#2      B    100  large
#3      C     60 medium

Answer 3

This will help you out -

# Creating a data frame 

M <- data.frame(c("A","B","C"),c(5,100,60))

names(M) <- c("Letter","Number")

#adding a column 


# if Number <= 50 Size is small, 
# if Number is between 50 and 70, Size is Medium
# if Number is Bigger than 70, Size is Big

# M$Size[M$Number <= 50] <- "Small"
# Edit: No need to subset "Small"
M$Size <- "Small"
M$Size[M$Number >50 & M$Number<70] <- "Medium"
M$Size[M$Number > 70] <- "Big"

#      Letter Number   Size
# 1      A      5      Small
# 2      B    100      Big
# 3      C     60      Medium

See this on R-Fiddle