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rdplyrseq

Create column in R that increments every row to length of dataframe

I would like to add a column to my dataframe that starts at 0 and increments 0.002 every row till the end of the dataframe.

I tried:

NewCol <- seq(0,len(DF),0.002))
DF <- cbind(DF, NewCol)

My desired output would be: 0.00 0.002 0.004 0.006 ...to the end of the dataframe

The NewCol length was too long to cbind to my dataframe.

Solution

  • We can use nrow for this inside the seq function like so

    df <- data.frame(a = c(1:5), b = 6:10)
  a b
1 1 o
2 2 c
3 3 p
4 4 u
5 5 d

df$num = seq(0, by = 0.002, to = nrow(df)*0.002 - 0.002)

# simplified by @Ritchie Sacramento to

df$num = seq(0, by = 0.002, length.out = nrow(df))

  a b   num
1 1 o 0.000
2 2 c 0.002
3 3 p 0.004
4 4 u 0.006
5 5 d 0.008