On Sat, Sep 14, 2013 at 12:35 PM, <gildororo...@mail-on.us> wrote:
> This is better explained by example:
>
>> A <- data.frame(force = sort(runif(10, 0, 1)), condition =
>> sort(sample(0:100, 10)))
>> B <- data.frame(counterforce = sort(runif(15, 0, 1), decreasing=T),
>> condition = sort(sample(0:100, 15)))
>
>
> So we have:
>
>> A
>
> force condition
> 1 0.03515542 1
> 2 0.13267882 13
> 3 0.26155689 24
> 4 0.37453142 38
> 5 0.39360520 45 <--- trim everything after this
> 6 0.43924737 48
> 7 0.47669800 50
> 8 0.57044795 51
> 9 0.81177499 61
> 10 0.98860450 94
>
>> B
>
> counterforce condition
> 1 0.965769548 2
> 2 0.965266255 5
> 3 0.846941244 7
> 4 0.818013029 11
> 5 0.813139978 22
> 6 0.730599939 34
> 7 0.715985436 39
> 8 0.658073895 40
> 9 0.421264948 42 <--- trim everything after this
> 10 0.373774505 52
> 11 0.242191461 62
> 12 0.090584590 63
> 13 0.070020635 68
> 14 0.067366062 83
> 15 0.001585313 84
>
> I need to trim away rows after No. 5, from A, trim away rows after No. 9,
> from B.
>
> Because
>
> A[5, condition] > max(B[1:9, condition] && A[5, force] > B[9+1,
> counterforce]
>
> In a general way, I am looking for x and y, where:
>
> A[x, condition] > max(B[1:y, condition] && A[x, force] > B[y+1,
> counterforce]
>
> and I will select A[1:x,] and B[1:y,], or trim away the rest, because they
> are irrelevent for the calculation onwards.
Try this:
library(sqldf)
r <- sqldf("select a.condition, b1.condition
from A a, B b1, B b2
where a.condition > b1.condition
and a.force > b2.counterforce
and b2.rowid = b1.rowid + 1
order by a.condition, b1.condition
limit 1")
Atrim <- fn$sqldf("select * from A where condition <= `r[1]` ")
Btrim <- fn$sqldf("select * from B where condition <= `r[2]` ")
giving:
> Atrim
force condition
1 0.03515542 1
2 0.13267882 13
3 0.26155689 24
4 0.37453142 38
5 0.39360520 45
> Btrim
counterforce condition
1 0.9657695 2
2 0.9652663 5
3 0.8469412 7
4 0.8180130 11
5 0.8131400 22
6 0.7305999 34
7 0.7159854 39
8 0.6580739 40
9 0.4212649 42
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