[R] convert microns to nm in a messy dataset
Ivan Calandra
c@|@ndr@ @end|ng |rom rgzm@de
Mon May 13 08:41:24 CEST 2019
Dear John,
Thank you for your answer.
However, it does not make sense to me, as it works only line by line of the
data.frame, and I need something for "last observation carried forward" as Peter
mentioned. The script does not work as is either, probably due to typos with
semi-colons and "if... else" statements, so I cannot really test it.
Best,
Ivan
--
Dr. Ivan Calandra
TraCEr, laboratory for Traceology and Controlled Experiments
MONREPOS Archaeological Research Centre and
Museum for Human Behavioural Evolution
Schloss Monrepos
56567 Neuwied, Germany
+49 (0) 2631 9772-243
https://www.researchgate.net/profile/Ivan_Calandra
On May 10, 2019 at 3:47 PM John McKown <john.archie.mckown using gmail.com> wrote:
> This is my approach. It is based entirely on what you said (multiply by 1000
> to convert from nm to µm, but I think it is divide by). It assumes that the
> starting value is in µm. If the starting value is in nm, change the
> "factor=1" to "factor=1000". That µm is micro-meters (10^-6) and nm is
> nano-meters (10^-9), so divide by would be correct.
>
> factor=1;
> for (i in 1:length(my.data$V19)) {
> print("Start");print(factor);print(my.data[i,]);
> if (my.data$V19[i] == "nm") { factor=1000; my.data$V19[i]="µm";print("nm");}
> else if (my.data$V19[i] == "µm") {factor=1;};
> if (suppressWarnings(! is.na <http://is.na> (as.numeric(my.data$V19[i])))) {
> my.data$V19[i] = as.character(as.numeric(my.data$V19[i]) * factor);
> print("changed"); }
> print(factor);print(my.data[i,]);print("End");
>
>
>
> On Fri, May 10, 2019 at 6:54 AM Ivan Calandra < calandra using rgzm.de
> <mailto:calandra using rgzm.de> > wrote:
> > > Dear useRs,
> >
> > Below is a sample of my dataset (I have more rows and columns).
> >
> > As you can see in the 2nd column, there are values, the name of the
> > parameter
> > ('Sq' in that case), some integer ('45' in that case) and the unit ('µm'
> > or
> > 'nm').
> > I know how to extract the rows of interest (those with values), but they
> > are
> > expressed in different units. All values following a line with the unit
> > are
> > expressed in that unit, but the number of lines is not constant
> > (sometimes each
> > value is expressed in a different unit so there will be a new unit line,
> > but
> > there are sometimes several values in a row expressed in the same unit so
> > without unit lines in between). I hope this is clear (it should be with
> > the
> > example provided).
> > This messy dataset comes from an external software so I don't have any
> > means to
> > format the ways the data are collated. I have to find a way to deal with
> > it in
> > R.
> >
> > What I would like to do is convert the values in nm to µm; I just need to
> > multiply by 1000.
> >
> > What I don't know is how to identify the values that are expressed in nm
> > (all
> > values that follow a line with 'nm' until there is a line with 'µm').
> >
> > I don't even know how I should search online because I don't know how
> > this kind
> > of operation is called.
> > Any help is appreciated.
> >
> > Thank you in advance.
> > Ivan
> >
> >
> > my.data <- structure(list(V1 = c("2019/05/10", "#", "#", "#",
> > "2019/05/10",
> > "2019/05/10", "2019/05/10", "#", "#", "#", "2019/05/10", "#", "#", "#",
> > "2019/05/10", "#", "#", "#", "2019/05/10", "2019/05/10"), V19 =
> > c("0.2012800083", "45", "Sq", "µm", "0.3634383236", "0.4360454777",
> > "0.3767733568", "45", "Sq", "nm", "102.013048", "45", "Sq", "µm",
> > "0.1413840498", "45", "Sq", "nm", "65.4459715", "46.45802917")),
> > row.names =
> > c(NA, 20L), class = "data.frame")
> >
> > --
> > Dr. Ivan Calandra
> > TraCEr, laboratory for Traceology and Controlled Experiments
> > MONREPOS Archaeological Research Centre and
> > Museum for Human Behavioural Evolution
> > Schloss Monrepos
> > 56567 Neuwied, Germany
> > +49 (0) 2631 9772-243
> > https://www.researchgate.net/profile/Ivan_Calandra
> > <https://www.researchgate.net/profile/Ivan_Calandra>
> >
> > ______________________________________________
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> > <http://www.R-project.org/posting-guide.html>
> > and provide commented, minimal, self-contained, reproducible code.
> > >
>
> --
> This is clearly another case of too many mad scientists, and not enough
> hunchbacks.
>
>
> Maranatha! <><
> John McKown
>
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