GIMP Version: 2.6
Operating System: Windows
GIMP Experience: Intermediate Level

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My script operates left to right across the image, moving each column in turn up or down randomly (by the inputted amount) relative to the previous column

The first image below is pre script

The second image is post script

Though it works the strange thing is, every time I close gimp and then reopen and run the script again (keeping the default value 4 pixels) the exact same image is generated, how can this be when its using the random function.

I assumed my script was at fault until I found I could get different image patterns, but to do so I needed to open the original image from within gimp

If anyone wishes to try it the script is placed on the menu bar, named Miscellaneous

Steve,
before using the random function you better set the random seed with a statement like:
(srand (car (gettimeofday))) ; set randon seed
otherwise the random function returns always the same values

That was quick i've been mulling this over for a week

This looks like it will solve my problem, many thanks

me too I learned that from another post, Gimpchat is spreading knowledge around!
It's like a ...Gimp-pedia!

@Steve
Since your script is modifying an existing image (rather than creating a new image from scratch) it would be more appropriate to use undo-group-start/end (rather than disable/enable).
Also the undo-group-end should be after the last command which changes the image contents - in this case that's the -flatten command.

ie:

wow that's cool reminds me of northern lights the way the gradient mixed randomly.

Thanks for taking the time to explain and put me on the right track, much appreciated

Thanks northern lights, i'll have to have a try at those