From: Duncan Murdoch <murdoch_at_stats.uwo.ca>

Date: Tue, 06 May 2008 12:43:16 -0400

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https://stat.ethz.ch/mailman/listinfo/r-help PLEASE do read the posting guide http://www.R-project.org/posting-guide.html and provide commented, minimal, self-contained, reproducible code. Received on Tue 06 May 2008 - 17:42:25 GMT

Date: Tue, 06 May 2008 12:43:16 -0400

On 5/6/2008 12:07 PM, Dr. Ottorino-Luca Pantani wrote:

> Dear R-users,

*> I have the following problem
**>
**> In a lab experiment I have to mix three solutions to get different
**> concentrations of various molecules in a cuvette
**>
**> I've used R to calculate the necessary µliters for each of the level of
**> the experiment and I must confess that it is more useful and easier to
**> achieve the results than using spreadsheets.
**>
**> But there's a problem.
**>
**> Imagine that for a particular cuvette (I have 112 different cuvettes !!)
**> you have to mix the following volumes of solution A, B, and C respectively.
**>
**> c(1803.02, 193.51, 3.47)
**>
**> Each solution is to be taken with 3 different pipettes (5000, 250 and 10
**> µL Volume max) and each of those delivers volumes in steps of 50 µL, 5
**> µL or 1µL, respectively
**> Since the above values would eventually become
**>
**> c(1800, 195, 3)
**>
**> it is then necessary to recalculate all the final concentrations
**> of A, B and C, because the volumes are changed.
**>
**>
**> I know that in most spreadsheets (Calc in Open Office, Gnumeric, Excel
**> and so on)
**> there's a function such as
**>
**> mround(num; num)
**>
**> that give the results I need, but I want to learn more on R functions.
**>
**>
**> I played a little with R functions such as
**>
**> round, signif, ceiling, trunc, and floor
**>
**> but without success.
**> Any hint to solve this problem ?
*

I believe this function matches the description in OOO:

mround <- function(number, multiple) multiple * round(number/multiple)

Duncan Murdoch

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https://stat.ethz.ch/mailman/listinfo/r-help PLEASE do read the posting guide http://www.R-project.org/posting-guide.html and provide commented, minimal, self-contained, reproducible code. Received on Tue 06 May 2008 - 17:42:25 GMT

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