Does anyone know why 'volcano' is oriented as it is?
image(volcano) ## filled.contour is the same
I know it's all arbitrary, but north-up is a pretty solid convention. Is
there any reason why the classic 'image()' example data set would not
default to this orientation?
A Google map of the site (in Web Mercator):
https://www.google.com/maps/place/Maungawhau+%2F+Mount+Eden/@-36.8763271,174.7619561,856m/data=!3m1!1e3!4m8!1m2!2m1!1smaungawhau!3m4!1s0x6d0d47db8d7bd1ff:0x8bcffe2a5c7360d2!8m2!3d-36.8666667!4d174.7666667
For image(), the north-up orientation is 't(volcano[,ncol(volcano):1])'.
If you are interested in a roughly georeferenced version I have code here:
https://gist.github.com/mdsumner/20fe3ffa04421bf8e0517c19085e5fd8
(Also see fortunes::fortune("conventions") )
Best, Mike
--
Michael Sumner
Software and Database Engineer
Australian Antarctic Division
Hobart, Australia
e-mail: mdsumner at gmail.com
[[alternative HTML version deleted]]
Hi, Hmmm. The only place I have ever seen a georeferenced version of 'volcano' is here... https://waterdata.usgs.gov/blog/inlmiscmaps/ It was on the internet so I assumed it was true. Now, I suspect that, since the original survey by Ross Ihaka, continental drift is happening waaaay faster than anyone guessed. Could be a decent grant proposal somewhere in all this. Seriously, though, I haven't any idea why 'volcano' is the way it is shown, nor was I awake enough to actually look at a map as you have done. I would love-love-love to see a georeferenced version be part of the stars package as example data. It's small enough to be lightweight but has enough information in it to be handy for meaningful demonstrations. Maybe along the lines of ... https://gist.github.com/btupper/8e8eb8c0ebf4402a3f87b5638eca954a ... but with the correct spatial info. Cheers, Ben On Sat, May 9, 2020 at 8:44 PM Michael Sumner <mdsumner at gmail.com> wrote:> Does anyone know why 'volcano' is oriented as it is? > > image(volcano) ## filled.contour is the same > > I know it's all arbitrary, but north-up is a pretty solid convention. Is > there any reason why the classic 'image()' example data set would not > default to this orientation? > > A Google map of the site (in Web Mercator): > > > https://www.google.com/maps/place/Maungawhau+%2F+Mount+Eden/@-36.8763271,174.7619561,856m/data=!3m1!1e3!4m8!1m2!2m1!1smaungawhau!3m4!1s0x6d0d47db8d7bd1ff:0x8bcffe2a5c7360d2!8m2!3d-36.8666667!4d174.7666667 > > > For image(), the north-up orientation is 't(volcano[,ncol(volcano):1])'. > > If you are interested in a roughly georeferenced version I have code here: > > https://gist.github.com/mdsumner/20fe3ffa04421bf8e0517c19085e5fd8 > > (Also see fortunes::fortune("conventions") ) > > Best, Mike > > > -- > Michael Sumner > Software and Database Engineer > Australian Antarctic Division > Hobart, Australia > e-mail: mdsumner at gmail.com > > [[alternative HTML version deleted]] > > ______________________________________________ > R-help at 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. >-- Ben Tupper Bigelow Laboratory for Ocean Science East Boothbay, Maine http://www.bigelow.org/ https://eco.bigelow.org [[alternative HTML version deleted]]
> Does anyone know why 'volcano' is oriented as it is? > image(volcano) ## filled.contour is the sameGreat question! graphics::image produces a "plot". It follows the same x y conventions as other plots in the graphics package. It's *defaults* are not designed to display photos, etc. However, the format of the volcano data is not consistent with either the defaults of graphics::image or what I (personally) would expect in a photographic data, with top-left value at top-left of matrix and bottom-right point at bottom-right of matrix, but that's debatable... According, the documentation of the volcano data: A matrix with 87 rows and 61 columns, rows corresponding to grid lines running east to west and columns to grid lines running south to north. Perhaps that could be improved slightly...? And one more thing that caught me out. My initial expectation (using a simple interpretation) was the data would need to be transposed and then either the ylim reversed or the rows reversed. But when I tried to plot the volcano data using my own function (which does just that), I got the wrong result. But in the documentation for graphics::image we have: "Need to transpose and flip" image(t(volcano)[ncol(volcano):1,]) Which produces the right result. I had to think about this for a while... The example for graphics::image above is actually transposing the matrix *twice*. First in the input to the function, and then again (implicitly), where rows (going down the data) are interpreted as x (going right across the plot).
Sorry, one more thing. My response didn't really answer your question. But I would say that the formats of most datasets used in statistics are reflective of the preferences of the people that collected or published them, at the time... Also, I've found the older publications quite often have considerable merit... On Sun, May 10, 2020 at 12:44 PM Michael Sumner <mdsumner at gmail.com> wrote:> > Does anyone know why 'volcano' is oriented as it is? > > image(volcano) ## filled.contour is the same > > I know it's all arbitrary, but north-up is a pretty solid convention. Is > there any reason why the classic 'image()' example data set would not > default to this orientation? > > A Google map of the site (in Web Mercator): > > https://www.google.com/maps/place/Maungawhau+%2F+Mount+Eden/@-36.8763271,174.7619561,856m/data=!3m1!1e3!4m8!1m2!2m1!1smaungawhau!3m4!1s0x6d0d47db8d7bd1ff:0x8bcffe2a5c7360d2!8m2!3d-36.8666667!4d174.7666667 > > > For image(), the north-up orientation is 't(volcano[,ncol(volcano):1])'. > > If you are interested in a roughly georeferenced version I have code here: > > https://gist.github.com/mdsumner/20fe3ffa04421bf8e0517c19085e5fd8 > > (Also see fortunes::fortune("conventions") ) > > Best, Mike > > > -- > Michael Sumner > Software and Database Engineer > Australian Antarctic Division > Hobart, Australia > e-mail: mdsumner at gmail.com > > [[alternative HTML version deleted]] > > ______________________________________________ > R-help at 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.
Hey, I know that volcano! It's walking distance from the Intermediate
school I attended.
To you it's a plot; to me it's a place.
So I offer you four scenarios.
1. You think of it as a place you know and have been.
In that case the "right" orientation is the one that best matches
what you are used to seeing.
For me, that would put the peak on the right of the plot.
2. You think of it as a patch in a map.
In that case the "right:" orientation is the one that matches the
map.
That would put the peak at the bottom of the plot.
3. You think of it as a product of geological processes, and are
perhaps interested in
whether there is any connection between the orientation of the
volcano and the
direction the Auckland hot-spot (currently at White Island) was moving.
In that case you'd choose south-west -> north-east as the primary
axis.
(I think. Not really sure.)
4. You think of it as a picture, an illustration in a textbook. It
might need to be cropped
vertically so you can fit another illustration on the same page.
For that and
perceptual reasons you want the major linear axis of the image to
be horizontal.
In that case, what we have now is a perfectly reasonable choice.
"Quality is fitness for use."
On Sun, 10 May 2020 at 12:44, Michael Sumner <mdsumner at gmail.com>
wrote:>
> Does anyone know why 'volcano' is oriented as it is?
>
> image(volcano) ## filled.contour is the same
>
> I know it's all arbitrary, but north-up is a pretty solid convention.
Is
> there any reason why the classic 'image()' example data set would
not
> default to this orientation?
>
> A Google map of the site (in Web Mercator):
>
>
https://www.google.com/maps/place/Maungawhau+%2F+Mount+Eden/@-36.8763271,174.7619561,856m/data=!3m1!1e3!4m8!1m2!2m1!1smaungawhau!3m4!1s0x6d0d47db8d7bd1ff:0x8bcffe2a5c7360d2!8m2!3d-36.8666667!4d174.7666667
>
>
> For image(), the north-up orientation is
't(volcano[,ncol(volcano):1])'.
>
> If you are interested in a roughly georeferenced version I have code here:
>
> https://gist.github.com/mdsumner/20fe3ffa04421bf8e0517c19085e5fd8
>
> (Also see fortunes::fortune("conventions") )
>
> Best, Mike
>
>
> --
> Michael Sumner
> Software and Database Engineer
> Australian Antarctic Division
> Hobart, Australia
> e-mail: mdsumner at gmail.com
>
> [[alternative HTML version deleted]]
>
> ______________________________________________
> R-help at 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.
Out of curiosity, and considering the bewildering array of projections and grids in use for various mapping purposes, you seem to be saying in your example 2 that the grid coordinates number south to north and east to west. Given scale of the coordinate numbers, would that be a national grid system employed in New Zealnd? J. W. Dougherty On Mon, 11 May 2020 13:56:49 +1200 "Richard O'Keefe" <raoknz at gmail.com> wrote:> Hey, I know that volcano! It's walking distance from the Intermediate > school I attended. > To you it's a plot; to me it's a place. > So I offer you four scenarios. > > 1. You think of it as a place you know and have been. > In that case the "right" orientation is the one that best matches > what you are used to seeing. > For me, that would put the peak on the right of the plot. > > 2. You think of it as a patch in a map. > In that case the "right:" orientation is the one that matches the > map. That would put the peak at the bottom of the plot. > > 3. You think of it as a product of geological processes, and are > perhaps interested in > whether there is any connection between the orientation of the > volcano and the > direction the Auckland hot-spot (currently at White Island) was > moving. In that case you'd choose south-west -> north-east as the > primary axis. (I think. Not really sure.) > > 4. You think of it as a picture, an illustration in a textbook. It > might need to be cropped > vertically so you can fit another illustration on the same page. > For that and > perceptual reasons you want the major linear axis of the image to > be horizontal. > In that case, what we have now is a perfectly reasonable choice. > > "Quality is fitness for use." > > On Sun, 10 May 2020 at 12:44, Michael Sumner <mdsumner at gmail.com> > wrote: > > > > Does anyone know why 'volcano' is oriented as it is? > > > > image(volcano) ## filled.contour is the same > > > > I know it's all arbitrary, but north-up is a pretty solid > > convention. Is there any reason why the classic 'image()' example > > data set would not default to this orientation? > > > > A Google map of the site (in Web Mercator): > > > > https://www.google.com/maps/place/Maungawhau+%2F+Mount+Eden/@-36.8763271,174.7619561,856m/data=!3m1!1e3!4m8!1m2!2m1!1smaungawhau!3m4!1s0x6d0d47db8d7bd1ff:0x8bcffe2a5c7360d2!8m2!3d-36.8666667!4d174.7666667 > > > > > > For image(), the north-up orientation is > > 't(volcano[,ncol(volcano):1])'. > > > > If you are interested in a roughly georeferenced version I have > > code here: > > > > https://gist.github.com/mdsumner/20fe3ffa04421bf8e0517c19085e5fd8 > > > > (Also see fortunes::fortune("conventions") ) > > > > Best, Mike > > > > > > -- > > Michael Sumner > > Software and Database Engineer > > Australian Antarctic Division > > Hobart, Australia > > e-mail: mdsumner at gmail.com > > > > [[alternative HTML version deleted]] > > > > ______________________________________________ > > R-help at 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. > > ______________________________________________ > R-help at 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.