[R] locating intervals

Martin Maechler maechler at stat.math.ethz.ch
Wed Aug 9 11:25:09 CEST 2006


I'm pretty sure you want to use

findInterval() 

Why did you not find it?
In other words,  what did you try to find it?

Regards,
Martin Maechler, ETH Zurich

>>>>> "halldor" == halldor bjornsson <halldor.bjornsson at gmail.com>
>>>>>     on Tue, 8 Aug 2006 16:47:18 +0000 writes:

    halldor> Hi , I have two sorted vectors X and Xi, where the
    halldor> range of Xi lies within the range of X.

    halldor> For an element in Xi, I want to find the
    halldor> neigbouring data in X, e.g. find an index ix so
    halldor> that for element number k, then X[ix[k]] < X[k] <
    halldor> X[ix[k] +1] # also OK with "<=" on either one, but
    halldor> not both

    halldor> This is easy to code by looping over the data in
    halldor> X,Xi, but I suspect there may be a faster and more
    halldor> elegant way to do this in R.

    halldor> In Python (Numeric) the same can be achieved with
    halldor> ix=Numeric.searchsorted(X[1:-1],Xi), which is quite
    halldor> compact.

    halldor> So, does anyone know of a corresponding R call that
    halldor> can achive the same?

    halldor> Sincerely, Halldór

    halldor> -- Halldor Bjornsson Weatherservice R & D Icelandic
    halldor> Met. Office



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