R: Meaning of "\" in Sapply?

Question

I have a dataset that looks something like this:

name = c("john", "john", "john", "alex","alex", "tim", "tim", "tim", "ralph", "ralph")
year = c(2010, 2011, 2012, 2011, 2012, 2010, 2011, 2012, 2014, 2016)
my_data = data.frame(name, year)

    name year
1   john 2010
2   john 2011
3   john 2012
4   alex 2011
5   alex 2012
6    tim 2010
7    tim 2011
8    tim 2012
9  ralph 2014
10 ralph 2016

I am trying to count the "number of rows with at least one missing (i.e. non-consecutive) year", for example:

# sample output

              year count
1       2014, 2016     1

In a previous question (Counting Number of Unique Column Values Per Group), I received an answer - but when I tried to apply this answer, I got the following error:

agg <- aggregate(year ~ name, my_data, c)
agg <- agg$year[sapply(agg$year, \(y) any(diff(y) != 1))]
as.data.frame(table(sapply(agg, paste, collapse = ", ")))

Error: unexpected input .... " ... \"

I think this error might be due to the fact that I am using an older version of R.

Does anyone know if an alternate symbol can be used to replace "" in R that is supported by older versions of R?

Thanks!

Your R version may not be uptodate. You can change `\(y)` to `function(y)`. It is anonymous lambda function i.e. `agg$year[sapply(agg$year, \(y) any(diff(y) != 1))][[1]]# [1] 2014 2016` — akrun, Dec 03 '22 at 18:43
I get the following error: Error in agg$year[sapply(agg$year, function(y) any(diff(y) != 1))][[1]] : subscript out of bounds — stats_noob, Dec 03 '22 at 18:57
Options if you can't upgrade your R version: https://stackoverflow.com/q/7833173/5325862 — camille, Dec 03 '22 at 18:59

akrun · Accepted Answer · 2022-12-03T21:58:42.550

3

In tidyverse, we may do this as

library(dplyr)
my_data %>% 
 group_by(name) %>% 
 filter(any(diff(year) != 1)) %>%
 summarise(year = toString(year)) %>%
 count(year, name = 'count')

-output

# A tibble: 1 × 2
  year       count
  <chr>      <int>
1 2014, 2016     1

The error in OP's code is based on the R version. The lambda concise option (\(x) -> function(x)) is introduced only recently from versions R > 4.0

edited Dec 03 '22 at 21:58

answered Dec 03 '22 at 18:46

akrun

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Inline functions were R 4.1, not 4.0 https://stat.ethz.ch/pipermail/r-announce/2021/000670.html – camille Dec 03 '22 at 18:57
@ akrun: thank you for your answer! When I try your code - I get an empty output: – stats_noob Dec 03 '22 at 18:58
# A tibble: 0 x 2 # ... with 2 variables: year , count – stats_noob Dec 03 '22 at 18:58
Is there something I am doing wrong? Thanks! – stats_noob Dec 03 '22 at 18:58
@ camille: thank you for this link! I will check it out! – stats_noob Dec 03 '22 at 19:12
1

@stats_noob sorry, it is > R 4.0 and not >= – akrun Dec 03 '22 at 21:59
@stats_noob Regarding your comment about the tidyverse output, it would also relate to the R version you may have. Please check your R version and update it to new version – akrun Dec 03 '22 at 22:05

R: Meaning of "\" in Sapply?

1 Answers1