[R] Summing using a boolean index vector (repost in plain text).
DStanger at EatonVance.Com
Fri Jun 18 19:12:20 CEST 2010
Thank you for getting back to me. Cumsum does exactly what I needed as the following example shows.
 TRUE FALSE FALSE FALSE TRUE FALSE FALSE FALSE FALSE TRUE FALSE FALSE FALSE FALSE TRUE FALSE
 1 1 1 1 2 2 2 2 2 3 3 3 3 3 4 4 4 4 4 5 5 5 5 5 6 6 6 6 6 7 7 7 7
Eaton Vance Management
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From: jim holtman [mailto:jholtman at gmail.com]
Sent: Friday, June 18, 2010 12:24 PM
To: Dan Stanger
Cc: R-help at r-project.org
Subject: Re: [R] Summing using a boolean index vector (repost in plain text).
But without data (follow the posting guide) specific solution can not
On Fri, Jun 18, 2010 at 11:39 AM, Dan Stanger <DStanger at eatonvance.com> wrote:
> Hello all:
> I have a dataframe f of weekdays and value, and a Boolean vector with Fridays set to true, and other days set to false, created by fridays<-(diff(f$weekdays) < -1).
> I would like to create a vector of sums, for each week. That is, start summing on the first false value in the vector, and when I get to true, produce the sum, and start summing again.
> Is there a vector operation which can do this, without writing an explicit loop?
> Thank you,
> Dan Stanger
> P.S. Sorry about the repost.
> Eaton Vance Management
> 200 State Street
> Boston, MA 02109
> 617 598 8261
> R-help at r-project.org mailing list
> PLEASE do read the posting guide http://www.R-project.org/posting-guide.html
> and provide commented, minimal, self-contained, reproducible code.
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