Hi. I built a weird little synthesizer as a web app at http://ji.quiethorn.com. I'm trying to replicate this in Pd but not sure how to manipulate Pd's arrays to do what I want. The way the web app works is

• it stores the ratios (fractions by which to multiply a base pitch) in an array
• then periodically chooses a random index from the array at the set tempo
• multiples the ratio value at that index with the base pitch
• and fires the oscillator at that new pitch

Ratios are added to/removed from the array by toggling them on and off in the display. This is the particular part I don't know how to replicate in Pd. In most languages (Javascript, Java, Python, etc.), you can append/remove an item in an array and the array will length will grow or shrink as needed, but this doesn't seem to be how Pd's arrays work. I kind of got it working somehow, but it's so convoluted and incomplete that I'm hoping there's just an easier way I'm missing.

I guess I need to have a metro that bangs a random generator, which generates an integer between 0 and a variable representing the length of the array, and also to be able to easily add and remove ratios (represented by floats) into the array by banging message or something...?

@quiethorn Popping pushing and shifting could be done in "extended" using [arraysize]....... see pd/doc/5.reference/all_about_arrays.pd which shows some techniques for that.
all_about_arrays.pd
That help file is gone from vanilla but the same can be done using [array size] to set and get array length.
David.

Thanks. I worked with [array size] a bit before and kinda got it working... make a bang to add/subtract 1 from the array size while adding/subtracting an index from it. But I don't know how to remove, for instance, the index of value 1.25 when it's in the middle of the array and have the array shrink to fit. I kinda wonder if it's just not possible and maybe I need to re-evaluate my approach to the whole thing.

@quiethorn In Pd, as far as I can tell so far, everything is possible.
Never despair.
This will do a removal and resize.......
this.zip
David.

If you're having trouble with arrays, then maybe you could try using lists? In general lists are less efficient than arrays, but a long as you're not working close to audio rate, it should be fine. The advantage of using lists is that it's easy to add and subtract elements without knowing their size.

If you don't mind using externals, the new release of Cyclone has an object called [zl] which will do anything you could possibly desire for lists. Ie. [cyclone/zl filter] will allow you to remove a single value from a list without having to worry about its position in the list.

Thanks, guys. @whale-av I'll go over that patch and figure out how it works.
@LiamG I'll check out lists too, but long term my hope is to turn this into an Android app with libpd, so I think I need to stay away from externals, right?

@quiethorn In case you ask..... here is the same, but with adding an index and its value as well.
The "removing an index" is the same as my previous post......
this.zip
David.