Improvement: function cut

Why would you want to merge different factors?

It makes no sense on real data. Even if some names are the same, the
factors are not the same!


The only real-data application that springs to mind is censoring (right
or left, depending on the choice): but here we have both open and closed
intervals, e.g. to the right (in the same data-set).


Leonard


On 9/18/2021 1:29 AM, Andrew Simmons wrote:

I disagree, I don't really think it's too long or ugly, but if you
think it is, you could abbreviate it as 'i'.


x <- 0:20
breaks1 <- seq.int <http://seq.int>(0, 16, 4)
breaks2 <- seq.int <http://seq.int>(0, 20, 4)
data.frame(
    cut(x, breaks1, right = FALSE, i = TRUE),
    cut(x, breaks2, right = FALSE, i = TRUE),
    check.names = FALSE
)


I hope this helps.

On Fri, Sep 17, 2021 at 6:26 PM Leonard Mada <leo.mada at syonic.eu
<mailto:leo.mada at syonic.eu>> wrote:

    Hello Andrew,


    But "cut" generates factors. In most cases with real data one
    expects to have also the ends of the interval: the argument
    "include.lowest" is both ugly and too long.

    [The test-code on the ftable thread contains this error! I have
    run through this error a couple of times.]


    The only real situation that I can imagine to be problematic:

    - if the interval goes to +Inf (or -Inf): I do not know if there
    would be any effects when including +Inf (or -Inf).


    Leonard


    On 9/18/2021 1:14 AM, Andrew Simmons wrote:

    While it is not explicitly mentioned anywhere in the
    documentation for .bincode, I suspect 'include.lowest = FALSE' is
    the default to keep the definitions of the bins consistent. For
    example:


    x <- 0:20
    breaks1 <- seq.int <http://seq.int>(0, 16, 4)
    breaks2 <- seq.int <http://seq.int>(0, 20, 4)
    cbind(
        .bincode(x, breaks1, right = FALSE, include.lowest = TRUE),
        .bincode(x, breaks2, right = FALSE, include.lowest = TRUE)
    )


    by having 'include.lowest = TRUE' with different ends, you can
    get inconsistent behaviour. While this probably wouldn't be an
    issue with 'real' data, this would seem like something you'd want
    to avoid by default. The definitions of the bins are


    [0, 4)
    [4, 8)
    [8, 12)
    [12, 16]


    and


    [0, 4)
    [4, 8)
    [8, 12)
    [12, 16)
    [16, 20]


    so you can see where the inconsistent behaviour comes from. You
    might be able to get R-core to add argument 'warn', but probably
    not to change the default of 'include.lowest'. I hope this helps


    On Fri, Sep 17, 2021 at 6:01 PM Leonard Mada <leo.mada at syonic.eu
    <mailto:leo.mada at syonic.eu>> wrote:

        Thank you Andrew.


        Is there any reason not to make: include.lowest = TRUE the
        default?


        Regarding the NA:

        The user still has to suspect that some values were not
        included and run that test.


        Leonard


        On 9/18/2021 12:53 AM, Andrew Simmons wrote:

        Regarding your first point, argument 'include.lowest'
        already handles this specific case, see ?.bincode

        Your second point, maybe it could be helpful, but since both
        'cut.default' and '.bincode' return NA if a value isn't
        within a bin, you could make something like this on your own.
        Might be worth pitching to R-bugs on the wishlist.



        On Fri, Sep 17, 2021, 17:45 Leonard Mada via R-help
        <r-help at r-project.org <mailto:r-help at r-project.org>> wrote:

            Hello List members,


            the following improvements would be useful for function
            cut (and .bincode):


            1.) Argument: Include extremes
            extremes = TRUE
            if(right == FALSE) {
                # include also right for last interval;
            } else {
                # include also left for first interval;
            }


            2.) Argument: warn = TRUE

            Warn if any values are not included in the intervals.


            Motivation:
            - reduce risk of errors when using function cut();


            Sincerely,


            Leonard

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