On 2020-08-21 09:03 +0200, Dr Eberhard Lisse wrote: > Hi, > > I have a small test sample with lab > reports (PAP smears) from a number of > different providers. These have > Collection Dates and the relevant > columns glimpse() something like > this: > > $ Provider <chr> "Dr C", "Dr D", "Dr C", "Dr D" > $ CollectionDate <chr> "2016-11-03", "2016-11-02", "2016-11-03", "2016-11-03" > > I am looking to find (filter) the > reports which were collected in the > time period common to all providers? > > Something like > > the largest First Common CollectionDate > and > the smallest Last Common CollectionDate > > How would I do that? > > I can of course do this "manually", ie > collect all Providers and their first > and last Collection dates and then > find the Common First and Last one, > but wonder if there is an elegant way > of doing this :-)-O
Dear Eberhard, Is each report in a csv file with those two columns, and you want to unify them into a dataframe with CollectionDate along the rows, and other details for each provider along the columns? This can be done with various apply calls and reshape. Can you please subset some more example data here using dput. It makes it so much easier. /Rasmus
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