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Understanding l_ply from plyr



2019 Community Moderator Electionmerging several data frames into a single expanded frameProblem loading the plyr packageLearning to understand plyr, ddplyWhy is plyr so slow?combining “quoted” objects from plyrSubset a list - a plyr way?understanding R performance plyr - dply and Factor variablesUnexpected result from plyr::aaplyWhat is most elegant way to loop through rows of a data frame with an impure function?How to define spacing of additional bar in barplot?










1















From the documentation:




All output is discarded. This is useful for functions that you are calling purely for their side effects like displaying plots or saving output.




I've spent some time playing around and trying to find a suitable use case but haven't(yet).



Looking at the examples hasn't helped me better understand it.



Sample usage:



l_ply(iris[1:5,1], function(x) print(summary(x)))


This will work.



However, under what circumstances might one need to print and then discard these results?










share|improve this question

















  • 1





    The example are simplified, in particular because side effects are not desirable in package examples. Typical functions passed would be plot, save, write.table ... All of these have (more) usefull side effects.

    – Roland
    yesterday
















1















From the documentation:




All output is discarded. This is useful for functions that you are calling purely for their side effects like displaying plots or saving output.




I've spent some time playing around and trying to find a suitable use case but haven't(yet).



Looking at the examples hasn't helped me better understand it.



Sample usage:



l_ply(iris[1:5,1], function(x) print(summary(x)))


This will work.



However, under what circumstances might one need to print and then discard these results?










share|improve this question

















  • 1





    The example are simplified, in particular because side effects are not desirable in package examples. Typical functions passed would be plot, save, write.table ... All of these have (more) usefull side effects.

    – Roland
    yesterday














1












1








1








From the documentation:




All output is discarded. This is useful for functions that you are calling purely for their side effects like displaying plots or saving output.




I've spent some time playing around and trying to find a suitable use case but haven't(yet).



Looking at the examples hasn't helped me better understand it.



Sample usage:



l_ply(iris[1:5,1], function(x) print(summary(x)))


This will work.



However, under what circumstances might one need to print and then discard these results?










share|improve this question














From the documentation:




All output is discarded. This is useful for functions that you are calling purely for their side effects like displaying plots or saving output.




I've spent some time playing around and trying to find a suitable use case but haven't(yet).



Looking at the examples hasn't helped me better understand it.



Sample usage:



l_ply(iris[1:5,1], function(x) print(summary(x)))


This will work.



However, under what circumstances might one need to print and then discard these results?







r plyr






share|improve this question













share|improve this question











share|improve this question




share|improve this question










asked yesterday









NelsonGonNelsonGon

3,1353730




3,1353730







  • 1





    The example are simplified, in particular because side effects are not desirable in package examples. Typical functions passed would be plot, save, write.table ... All of these have (more) usefull side effects.

    – Roland
    yesterday













  • 1





    The example are simplified, in particular because side effects are not desirable in package examples. Typical functions passed would be plot, save, write.table ... All of these have (more) usefull side effects.

    – Roland
    yesterday








1




1





The example are simplified, in particular because side effects are not desirable in package examples. Typical functions passed would be plot, save, write.table ... All of these have (more) usefull side effects.

– Roland
yesterday






The example are simplified, in particular because side effects are not desirable in package examples. Typical functions passed would be plot, save, write.table ... All of these have (more) usefull side effects.

– Roland
yesterday













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