Question

I have a dataframe containing two columns. One is for a number, the other one is for a Label
Example

1 200 A
2 300 B
3 350 C
4 2000 A
5 2200 D
6 2300 K

I want basically to segment this dataframe and to transform the second column into a vector containing words in the condition that the difference betweem any two values on the first column is < 1000

Expected Result is

C("ABC","ADK")

Example here we will have a vector C having ABC and ADK as words because the difference between row4 and row3 > 1000

Any idea on how to do it without consuming a lot of computing ?

Answer 1

Edited based on your clarification

# SAMPLE DATA
df <- data.frame(Col1=c(200, 300, 350, 2000, 2200, 2300, 4500), Col2=c("A", "B", "C", "A", "D", "K", "M"))
df

# Make sure they are the correct mode
df$Col1 <- as.numeric(as.character(df$Col1))
df$Col2 <- as.character(df$Col2)

lessThan <- which(abs(df$Col1[-length(df$Col1)] - df$Col1[-1]) > 1000 )

lapply(lessThan, function(ind)
  c( paste(df$Col2[1:ind], collapse=""),
      paste(df$Col2[ind+1:length(df$Col2)], collapse="") )
)

RESULTS:

  [[1]]
  [1] "ABC"   "ADKM"

  [[2]]
  [1] "ABCADK" "M"