Saved images are not updated

[novoselt]

@interact
def _(k=2):
    plot(sin(k*x)).save("p.png")
    html(r"""<img src='cell://p.png'/>""")

Changing k has no effect on the shown picture due to caching. I've found a trick to make it work by adding time in the end of the link:

@interact
def _(k=2):
    plot(sin(k*x)).save("p.png")
    html(r"""<img src='cell://p.png?%s'/>""" % walltime())

• perhaps this has to happen automatically?

[jasongrout]

If you are trying to display the image, can't you just do:

@interact
def _(k=2):
    plot(sin(k*x)).show()

You're right that if you specifically use the html, you'll probably also have to worry about caches. I hesitate to modify the url (beyond the cell://), but maybe we can have the server tell the client not to cache the file.

[novoselt]

I wanted to display several images arranged neatly, so I was doing it via html table referring to saved files. It does work fine in the worksheet mode, so I think it is quite desirable to have it work for cell server as well. I agree that automatic decoration of links is non-trivial and it would be better to avoid it.

[jasongrout]

I should note that you don't have to explicitly manage images to do a table:

http://sagecell.sagemath.org/?z=eJzLLygpVrBVqFZPy0wvzqxKVbdSMKrlyijJzdErSUzKSdWIji7IyS_RqIgz0tHSygeq1tRRAIsUZ-ZpVGjCBGN1YOqM4erAAjlgVRoVOgY6hgjVsZoAkiUm5g==&lang=sage

[novoselt]

That's definitely a more elegant solution for what I was doing! But the main issue as I see it is the discrepancy between different versions of interacts. I can imagine saving some files, running some external programs on them, and then trying to display the result stored as a file, which will return to the same problem.

Also I don't know how to correctly fix this issue, so if you are convinced that it is invalid - feel free to close it.

[novoselt]

... and actually I cannot easily do what I want with html.table: I prepare the plots and then save them with a bunch of options, e.g. figsize. I don't see a public way to adjust it for an existing plot: SHOW_OPTIONS changes defaults, Graphics() does not take arguments (and in any case plot parameters don't behave very well under addition). Using save(<parameters>) and then explicit HTML reference to display them seems quite natural...

[jasongrout]

I think it might be as easy as something like: http://stackoverflow.com/questions/12031007/disable-static-file-caching-in-tornado

I suppose a cell:// url will always be getting a file, so maybe there's no harm in appending an argument. I wonder how the notebook does it.