How to calculate number of times the same value appears consecutively in R or Excel?

Question

I have a data set where I'm trying to analyse how many times the same value appears consecutively. For example (based on the below data): 'The value '1' appears 3 times in a row from 1/1/2000-1/3/2000'

Example dataset

date, value
1/1/2000,1
1/2/2000,1
1/3/2000,1
1/4/2000,3
1/5/2000,3
1/6/2000,1
1/7/2000,3
1/8/2000,3
1/9/2000,3
1/10/2000,3

How should the problem be approached in either R or Excel?

Answer 1

As mentioned rle() will calculate run lengths. You can then use aggregate() to obtain the maximum run length by each grouping factor.

df <- structure(list(id = c("A", "A", "A", "B", "B"),
                     var = c("atc", "atc", "atc", "atc", "atc"),
                     val = c("aaa", "bbb", "ccc", "aaa", "eee")),
                .Names = c("id","var", "val"), class = "data.frame",
                row.names = c(NA, -5L))
# var and val are nonsense columns for padding

# How many times does each id appear sequentially?
df$run <- sequence(rle(df$id)$lengths)
df
  id var val run
1  A atc aaa   1
2  A atc bbb   2
3  A atc ccc   3
4  B atc aaa   1
5  B atc eee   2

aggregate(df, by = list(df$id), FUN = max)
  Group.1 id var val run
1       A  A atc ccc   3
2       B  B atc eee   2

Answer 2

In Excel, this can be done via an Array Formula.

Suppose your values are in column B, say in the range B2:B31 and the value you want to check for is in cell E3 , you could use the following formula:

=MAX(FREQUENCY(IF($B$2:$B$31=E3,ROW($B$2:$B$31)),IF($B$2:$B$31<>E3,ROW($B$2:$B$31))))

And enter it as an array formula (meaning, once entered, press CTRL+SHIFT+ENTER

Hope this does the trick!