Create new variable in R based on order of another variable

Question

I'm attempting to add another column to a data frame in R, based on the order of values of another variable in the data frame, for which many rows have the same value. So, I would like this new column to essentially be an ordinal version of the previous column, with all the rows that have the same, lowest value in that column assigned 1, and so on. Is there an easy way to do this?

(The data attached here is only the first few rows and does not have any repeats, but the full data set has in total 75 unique values, over 100.000 observations)

…   Value
1   0.6215278
2   0.5801653
3   0.5287239
4   0.5267176
5   0.5295736
6   0.5422419
7   0.5269841
8   0.5302013
9   0.5017794

@DanielO order won't work with the requested tie behavior "all the rows that have the same, lowest value in that column assigned 1". With order there can be only one 1. — Gregor Thomas
– Gregor Thomas, Commented May 12, 2020 at 17:46

akrun · Accepted Answer · 2020-05-12 18:25:26Z

2

Another option with frank

library(data.table)
frank(x, ties.method = 'dense')

data

x <- c(1, 1, 2, 3, 3, 4)

answered May 12, 2020 at 18:25

akrun

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Gregor Thomas · Accepted Answer · 2020-05-12 17:54:34Z

1

The rank function is what you're looking for. It sounds like you want it with the argument ties.method = "min", but see the help page for other options. This will leave gaps, e.g., if 2 entries are tied for first place, the next one will get rank 3...

x = c(1, 1, 2, 3, 3, 4)
rank(x, ties.method = "min")
# [1] 1 1 3 4 4 6

If you don't want gaps use dplyr::dense_rank.

dplyr::dense_rank(x)
# [1] 1 1 2 3 3 4

answered May 12, 2020 at 17:54

Gregor Thomas

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