[OGRUG] Newbie needs help with plot

[clark richards]

Hi Martin,

It helps if you show us what it was you tried to do, and exactly what
your errors were. The closer you can make your code sample to being
reproducible, the easier it is for others to see where you went wrong.
You can even attach your data file if that might be related to your
problem.

>From reading your email however, it sounds like the issue you are
having is how to reference the variables (i.e. columns) inside the
data.frame object that you imported (I'm assuming you used
`read.csv()` or something similar). If your columns were imported with
the names from the file (here is where seeing your code and having
your data file would help with the answer) you can reference the
individual field use the "$" notation, like:

> Voltage_202004$DoM

and you could then make a plot by doing, e.g.

> plot(Voltage_202004$DoM, Voltage_202004$VAC)

The `with()` function can be handy if you are plotting columns all
from the same data.frame object, and would be used like:

> with(Voltage_202004, plot(DoM, VAC))

If your columns aren't named, the best thing to do is name them in the
object and then proceed as above. To name columns you can do

> names(Voltage_202004) <- c('DoM', 'HoD', 'VAC')

Otherwise you can use the "numeric" approach to specifying which
columns you want to plot, e.g.

> plot(Voltage_202004[[1]], Voltage_202004[[3]]) # plots the first and 3 columns against each other.

Hope that helps!

Cheers,
Clark


On Mon, Sep 14, 2020 at 9:04 PM Martin Potter <mpotter using storm.ca> wrote:
>
> Hello,
>
> Newbie here with a newbie question.
>
> I have a time series of voltage measurements, two independent
> variables (DoM and HoD) and one dependent (VAC) variable.  My csv file
> was imported into R and now the 3-column table of values appears in
> the upper left panel of RStudio.  Good so far.
>
> I succeeded in getting the expected matrix of plots using the 'pairs'
> function :
>
> pairs(Voltage_202004, cex=1, pch=16, cex.labels = 2)
>
> so that works fine.
>
> But I have not been able to get any plots using 'plot', or variants of
> it, and get only errors, usually of the "object 'HoD' not found" variety.
>
> I suspect I need to declare my variable names somehow so that R will
> know what I am asking it to do, but have not been able to figure out
> how to do that.  There might be other things I need to do as well!
>
> Could someone show me an example of (1) how to declare my variables
> and (2) exactly what an xy plot command should look like, using my
> variable names (DoM, HoD, and VAC), plotting VAC against either DoM or
> HoD?
>
> Thanks for any help with this!  All of my Help material seems very
> abstract at this point, and so far has not be of much help to me. Many
> years ago I cut my teeth on FORTRAN and soon graduated to assembler
> language on a DEC PDP-8 in a small data acquisition and processing
> lab, before moving on to other jobs.  Since then the vocabulary seems
> to have changed considerably and this now almost-80-year-old gets
> easily confused.
>
> ... Martin Potter
>
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