Dear ,
On 2023-03-23 11:08 a.m., Anupam Tyagi wrote:
Thanks, John.
However, loess.smooth() is producing a very different curve compared to
the one that results from applying predict() on a loess(). I am guessing
they are using different defaults. Correct?
No need to guess. Just look at the help pages ?loess and ?loess.smooth.
If you don't like the default for loess.smooth(), just specify the
arguments you want.
Best,
John
On Thu, 23 Mar 2023 at 20:20, John Fox <[email protected]
<mailto:[email protected]>> wrote:
Dear Anupam Tyagi,
You didn't include your data, so it's not possible to see exactly what
happened, but I think that you misunderstand the object that loess()
returns. It returns a "loess" object with several components, including
the original data in x and y. So if pass the object to lines(), you'll
simply connect the points, and if x isn't sorted, the points won't
be in
order. Try, e.g.,
plot(speed ~ dist, data=cars)
m <- loess(speed ~ dist, data=cars)
names(m)
lines(m)
You'd do better to use loess.smooth(), which is intended for adding a
loess regression to a scatterplot; for example,
plot(speed ~ dist, data=cars)
with(cars, lines(loess.smooth(dist, speed)))
Other points: You don't have to load the stats package which is
available by default when you start R. It's best to avoid attach(), the
use of which can cause confusion.
I hope this helps,
John
--
* preferred email: [email protected]
<mailto:[email protected]>
John Fox, Professor Emeritus
McMaster University
Hamilton, Ontario, Canada
web: https://www.john-fox.ca/ <https://www.john-fox.ca/>
On 2023-03-23 10:18 a.m., Anupam Tyagi wrote:
> For some reason the following code is not plotting as I want it
to. I want
> to plot a "loess" line plotted over a scatter plot. I get a
jumble, with
> lines connecting all the points. I had a similar problem with
"lowess". I
> solved that by dropping "NA" rows from the data columns. Please help.
>
> library(stats)
> attach(gini_pci_wdi_narm)
> plot(ny_gnp_pcap_pp_kd, si_pov_gini)
> lines(loess(si_pov_gini ~ ny_gnp_pcap_pp_kd, gini_pci_wdi_narm))
> detach(gini_pci_wdi_narm)
>
--
Anupam.
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