[R] filter() question

[Rasmus Liland]

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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