Export data.table:::uniqlist for external use

uniqlist is useful to detect whether there's a change in value in an R's data frame. (For example, check if a variable change values in time series data.)

See this StackOverflow question, which shows that there's no readable alternative to uniqlist

x = data.frame(cnt=1:10, code=rep('ELEMENT 1',10), val0=rep(5,10),  val1=rep(6,10),val2=rep(3,10))
x[4,]$val0=6

data.table:::uniqlist(x[, 3:5])
# [1] 1 4 5

I was looking for this functionality and found the StackOverflow post mentioned by LaDilettante with Arun's suggestion to file an issue in GitHub. I then discovered this opened issue. I too am now using uniqlist and would like to see it exported. Thanks for the useful work.

I think we should rename this function for exporting. Current name will be confusing, as we now have rbindlist (do.call(rbind, ...)), and cbindlist and mergelist are coming to also provide corresponding reduction using cbind and merge.
If anyone has some idea for new name please put your feedback here.
According to comments in code, and reference to base::order, which mentions bash uniq, the name uniq seems reasonable.

exporting uniq function (uniqlist), #900

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Export data.table:::uniqlist for external use #900

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Export data.table:::uniqlist for external use #900

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jangorecki commented on Oct 19, 2014

kenklin commented on Aug 11, 2015

jangorecki commented on Apr 10, 2020

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