Читать книгу The Big R-Book - Philippe J. S. De Brouwer - Страница 159

Assigning a default value to the argument of a function means that this argument will get the default value, unless another value is supplied – in other words: if nothing is supplied then the default is used.

It is quite handy to have the possibility to assign a default value to a function. It allows to save a lot of typing work and makes code more readable, but it allows also to add a variable to an existing function and make it compatible with all previous code where that argument was not defined.

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