R what is the difference between library and require

That is too late and sometimes difficult for other people to understand if they use your script but are not familiar with the foo package — they may ask, what is the bar object, and where is it from? When your code is going to fail, fail loudly, early, and with a relevant error message.

Sometimes you do need require to use a package conditionally e. That should be what require was designed for, but it is common to see R code like this as well:. Then if! I do not quite understand why it is worth the circle, except when one wants a different error message with the one from library , otherwise one can simply load and fail. What is the difference between [] and [[]] notations to access the elements of a list or dataframe in R? What is the difference between list and vector in R?

What is the difference between merge and bind in R? What is the Difference in Size and Count in pandas python? What is the difference between correlation and covariance? What is the difference between random forest and decision trees? What is the difference between rnorm and runif functions? How to find out the package version which is loaded in R? Welcome back to the World's most active Tech Community!

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Always use library. Never use require. Konrad Rudolph Konrad Rudolph k gold badges silver badges bronze badges. I was gonna point exactly the same, unless you are calling ALL the functions with the syntax class::function , use library to avoid precisely that. MichaelChirico This answer is being discussed on meta. David Arenburg Shape Shape 2, 17 17 silver badges 31 31 bronze badges. KonradRudolph well, if someone is going to fix library, maybe they can also enable loading by version explicitly and make attachment an argument option — Shape.

Yes, I absolutely agree but those would change the semantics, not just the performance. Anyway, versioning will never work with packages in R, unfortunately. As for attaching, you can use loadNamespace , which loads a package and returns its namespace, without attaching it. The Overflow Blog. Does ES6 make JavaScript frameworks obsolete? Podcast Do polyglots have an edge when it comes to mastering programming Featured on Meta.

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