Michael,

This will get you started.  What you are doing with the seven rows isn't
clear
from your description.  I made the dates into "Date" objects.  I called your
data
"mydata" as "data" is potentially ambiguous.

Rich



mydata <- read.table(header=TRUE, textConnection("
          ds c1 c2
1  2010-04-03        100           0
2  2010-04-30      11141          15
3  2010-05-01      3          16
4  2010-05-02       7615          14
5  2010-05-03       6910          17
6  2010-05-04       5035          3
7  2010-05-05       3007          15
8  2010-05-06       4          14
9  2010-05-07       8335          17
10 2010-05-08       2897          13
11 2010-05-09       6377          17
12 2010-05-10       3177          17
13 2010-05-11       7946          15
14 2010-05-12       8705          0
15 2010-05-13       9030          16
16 2010-05-14       8682          16
17 2010-05-15       8440          15
"))

mydata$ds <- as.Date(mydata$ds)
result <- 0
for (i in seq(length=nrow(mydata)-6)) {
  ## do something with
  mydata[i:(i+6), 2:3]
  ## and
  c(100, 8)
  if (TRUE) {
    result <- i  ## I am returning the start row, not the generic 1.
    break
  }
}
result

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