[Bioc-devel] Adding a lengths() method to List class

Change was made. Should dispatch to length and [[ methods.

On Wed, Sep 30, 2015 at 9:37 PM, Herv? Pag?s <hpages at fredhutch.org> wrote:

On 09/30/2015 05:28 PM, Michael Lawrence wrote:

It wasn't a conscious choice, but it would slow things down a bit. Not
by much though, since we're already attempting dispatch on length(). I
can make the change.

That would be great. Thanks Michael!

H.

On Wed, Sep 30, 2015 at 1:33 PM, Herv? Pag?s <hpages at fredhutch.org
<mailto:hpages at fredhutch.org>> wrote:

    Hi Michael,

    I was expecting this to just work:

       base::lengths(IntegerList(1:4, 1:6))

    but it doesn't:

       Error in base::lengths(IntegerList(1:4, 1:6)) :
         'x' must be a list or atomic vector

    The man page says:

          This function loops over ?x? and returns a compatible vector
          containing the length of each element in ?x?.  Effectively,
          ?length(x[[i]])? is called for all ?i?, so any methods on
?length?
          are considered.

    If length(x[[i]]) is called for all i then it should work on any
object
    for which [[ is defined. Note that this is what happens with
    base::sapply(), base::mapply(), etc... they all use [[ internally.

    Do you know of any reason why lengths() doesn't do this?

    Thanks,
    H.


    On 09/28/2015 09:51 PM, Michael Lawrence wrote:

        That is the plan. Note that we already have elementLengths()
        that serves
        the same purpose. It was the direct inspiration for lengths().

        On Mon, Sep 28, 2015 at 9:41 PM, Peter Hickey
        <peter.hickey at gmail.com <mailto:peter.hickey at gmail.com>>
        wrote:

            The lengths() function was added in R 3.2 to "get the length
            of each
            element of a list or atomic vector (is.atomic) as an integer
            or numeric
            vector." It seems useful to me to have also a similar method
            defined for
            the S4Vectors::List class (and subclasses). What do others
            think?

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--
Herv? Pag?s

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