[R] convert microns to nm in a messy dataset [solved]

[Ivan Calandra]

Dear Peter,

Thank you for your answer, the function na.locf() is exactly what I needed!
I had started processing my dataset so the first lines (used as headers) were
not included in the sample I have sent. But there is also a "unit" line before
the first value.

And yes, of course, divide by 1000.

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 3:29 PM peter dalgaard <pdalgd using gmail.com> wrote:
> From nm to micron, _divide_ by 1000.... (as you likely know)
>
> What are the units of the first value? Looks like micron in your example, but
> is there a rule?
>
> Basically, it is a "last observation carried forward" type problem, so
> something like this:
>
>
> 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")
>
> y <- my.data$V19
> u <- ifelse(y=="nm" | y=="µm", y, NA)
> num <- my.data$V1 != "#"
> uu <- zoo::na.locf(u, na.rm=FALSE)
> data.frame(val = as.numeric(y[num]), units = uu[num])
>
> giving
> val units
> 1 0.2012800 <NA>
> 2 0.3634383 µm
> 3 0.4360455 µm
> 4 0.3767734 µm
> 5 102.0130480 nm
> 6 0.1413840 µm
> 7 65.4459715 nm
> 8 46.4580292 nm
>
> and you can surely take it from there.
>
> -pd
>
>
> > On 10 May 2019, at 13:54 , Ivan Calandra <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
> >
> > ______________________________________________
> > R-help using r-project.org mailing list -- To UNSUBSCRIBE and more, see
> > 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.
>
> --
> Peter Dalgaard, Professor,
> Center for Statistics, Copenhagen Business School
> Solbjerg Plads 3, 2000 Frederiksberg, Denmark
> Phone: (+45)38153501
> Office: A 4.23
> Email: pd.mes using cbs.dk Priv: PDalgd using gmail.com
>
>
>
>
>
>
>
>
>
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