Compo returns

Does anyone use RAR these days?

Pirates, that don’t want stuff disclosed by automated scanning of zip files…

In more seriousness, Rar has some nice features:

• Ability to split a large archive into smaller files which are treated as a whole (this meant a lot when floppies were a thing)
• Ability to add an amount of overhead for recovery data. If your media is corrupt, your zip archive (or parts of it) will be screwed. With Rar it might be recoverable.
• Better encryption. Maybe moot with 7Zip in 2024, but BITD…
• It also offered better, faster, compression than the Zip Deflate that was common back then.

Back on topic (ahem) I’m just finishing another article/webpage on using CompoScript. This time it plots polar patterns of the gain versus angle of and antenna. Plotted two different antenna patterns as an example. While doing it by ‘painting’ pixels I realised it can also be done by using some small drawfiles to place on the canvas – thus giving more variety of point markers and probably looks nicer due to anti-aliasing.

Work on the new edition of the Compo/PCA Applets manual has progressed. Its current draft is downloadable from here

I have summarised the broad changes in the front matter, and added PDF bookmarks that even !PDF can use.

I need to do some more proof-reading, checking and tidying, but more critical is whether all the tutorial and reference content is accurate and reliable. For that I would welcome the experiences of interested users of the application.

Feedback, please! But preferably not here among Announcements. If you want to be public, why not start a new thread in Community support or in General, or else email me privately at b dot boase at bcs dot org?

New thread in Community support

@Jim
I couldn’t find your article, you didn’t have time to publish it?
It’s good to see Compo used for this kind of publication, a good Risc OS tool!
I’m trying to draw wave radiation plots with Pari/gp from equations, I get a Draw file.

Example:  Cardioïde
 ploth(x =0, 2*Pi, [2*(1+cos(x)) *cos(x), 2*(1+cos(x))*sin(x)] ,"Parametric" )

@Bernard
nice to have a readable and up-to-date manual

The Archive magazine articles are ‘in the press’. However I have now added another webpage to the “Revived” section of my site. The new pages are:

https://jcgl.orpheusweb.co.uk/CompoRevival/CompoRevived.html Which shows the ‘colour field’ plots of the field levers around some antennas

https://jcgl.orpheusweb.co.uk/CompoRevival2/CompoRevived-pt2.html Which examples how CompoScript can be used to plot graphs from sets of values in a data file.

Each provides a zip of the program for people to try and examine.

Next step is to demo being able to analyse the patters in a graphic and extract measurement. Potential to take images of graphs, etc, and obtain measured values from them.

Be nice if Fireworkz could have a spreadsheet mechanism to export a data set to a script…and monitor a Draw file for changes :-)

Thanks Jim test ok.
Interesting about the precalculated data,

@Suart
Exporting data can be done in csv format, I think it is possible to build an application that uses this data to create a draw file, but that’s already what it does!Fireworkz, I must not have fully understood your sentence.

Producing a draw file is interesting with !Compo because it can use them to compose an image or animation.

Exporting data can be done in csv format, I think it is possible to build an application that uses this data to create a draw file, but that’s already what it does!Fireworkz, I must not have fully understood your sentence.

I meant adding a new spreadsheet formula like =EXPORT(array_or_range, filename, task_to_run) so that whenever the referenced data changed, it would be CSVed to the file and task_to_run filename executed.

Thanks for your answer, a Fireworkz feature.

In principle, the WimpTask call could – I presume – call a program to calculate a data set, and then have !Compo plot it. (Not sure if that would need a second WimpTask call or not because I’ve not tried it!) CompoScrip does let you use a click on an object run a process of some kind. As per the ‘slideshow’ demo.

However: Once I have some more “round tuits” my interest is in image analysis and data extraction from images. From simple – like determining the area of a shaped block or outline – to more complex – like reading spectam vs time plots to get info like anharmonic distortions of audio signals.

The general point to example that CompoScript opens a pretty wide area of things a user may wish to do to/with ‘graphics’. Not just pretty pictures.

reading spectam vs time plots to get info like anharmonic distortions of audio signals.

Jim, during our collaboration with Colin Granville, I created a Desktop version of your USBScope application, it works correctly and displays the information (measurement + Tool tip cursor) on the audio signal coming from a USB device, and this in real time.

We can therefore use it with other applications, like Rhapsody or !Midiplayer, not bad for a cooperative system…

For fun, I play a note on a score with Rhasody and depending on the instrument chosen I can look at its spectrum and alos see that the A is not at 440Hz, note: I use an expander.

To test:
http://jeanmichelb.riscos.fr/Audio/AudioJimLesurf.html

Your desktop versions are excellent. Not something I can easily do so I just single-task. The limit is my mind which also can only cope with a max of one (sloow) thing at a time! 8-] However…

When I wrote “reading spectrum vs time plots” I was meaning a situation where you have a bitmap image of a spectrum and use !Compo to numerical extract values for the level versus frequency and time. That could then be used for further analysis, etc.

Simple case being something like a PNG of an XY plot of level versus frequency as your input. Then use Compo to extract values for the level at each frequency across the bitmap’s graph.

Useful if you see a graphic on a printed page or webpage and want to get the data to examine and check, etc. But the authors haven’t give you the data, just the bitmap.

FWIW I just did screengrabs (Linux) from VLC playing this month’s “Sky at night” BBC TV prog with the thought the grabs can be used to test this idea. One graph is simple. The other is more complex. But could be ‘scanned’ pixel-by-pixed via Composcript to get data – or to seperate different lines of data that have different colours if you want data on a specific plot line or to plot that without the others, etc.

Does that give some idea of the scope? As a (retired) ‘measurements scientist/engineer’ it’s something I have an interest in.

Thank you for your reply.
And your clarifications. I’m more used to having data to plot than the other way around. I didn’t know that !Compo allows you to do it the other way around…
I’m retired too, and I still have a lot to explore.

Nice thing about Compo is that it can be used at the pixel level to process one bitmap to compare it with or create others. e.g. could do colour separations where an input colour image could create three new images – each one just showing the R, G, or B, parts of the image!

or use one image to mask another, perhaps in just one colour channel.

And using whatever programming language you fancy that runs on a RO machine.

The link to Compo manual thread in Community support, provided above by Steve Pampling, should point here.