Georgios Varnavides•5mo ago

Recommended way for self-triggering computation / semi-infinite loop?

Is there a recommended way to trigger a cell (which mutates state) to re-run after it's done -- under some conditions? I was under the impression the following combination of switch/stop would do the trick, but it doesn't seem to be able to escape the infinite loop?

import marimo as mo
import random
import time

import marimo as mo
import random
import time

get_seconds, set_seconds = mo.state(1)

get_seconds, set_seconds = mo.state(1)

def expensive_computation():
    seconds = get_seconds()
    time.sleep(seconds)
    set_seconds(random.randint(1,3))

def expensive_computation():
    seconds = get_seconds()
    time.sleep(seconds)
    set_seconds(random.randint(1,3))

infinite_loop = mo.ui.switch(
    False,
    label="infinite loop",
)
infinite_loop

infinite_loop = mo.ui.switch(
    False,
    label="infinite loop",
)
infinite_loop

mo.stop(not infinite_loop.value)
expensive_computation()

mo.stop(not infinite_loop.value)
expensive_computation()

My actual use-case (https://marimo.io/p/@gvarnavides/iterative-ptychography) is less contrived. Essentially I'd like to plot the output of an iterated map at every iteration. Right now, I'm doing it with mo.ui.refresh - which works well, but I'd like a "as quick as possible" update instead of fixed time-increments (since the computation time varies with batch_size).

marimo | Iterative Ptychography

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11 Replies

Myles Scolnick•5mo ago

On set_state, I think there is an include_self flag you can pass The refresh button has network latency and other latencies included so not great as an accurate timer

Georgios VarnavidesOP•5mo ago

I played around with include_self and it doesn't seem to help (in-fact presumably the default False is designed to capture this infinite-loop behaviour?)

Myles Scolnick•5mo ago

I think you can put get and set in the same cell and use include_self

Georgios VarnavidesOP•5mo ago

Not sure that's the issue? like I can get set/get to loop infinitely just fine. I just want a way to kill that once it's running. The following doesn't seem to work

mo.stop(not infinite_loop.value)
expensive_computation()

mo.stop(not infinite_loop.value)
expensive_computation()

playground here: https://marimo.app/?slug=19s2hr

marimo | a next-generation Python notebook

Explore data and build apps seamlessly with marimo, a next-generation Python notebook.

Myles Scolnick•5mo ago

oh sorry I misunderstood. Hmm yea I’m not sure how to interrupt that

Georgios VarnavidesOP•5mo ago

I wondered if the on_change parameter of the mo.ui.switch input could be used to emit some sort of event to break the set/get cycle, but not sure what that would be

Myles Scolnick•5mo ago

Could you raise an error?

Georgios VarnavidesOP•5mo ago

wow, that doesn't seem to bother it either haha

def raise_(val):
    if not val:
        raise ValueError()

infinite_loop = mo.ui.switch(
    False,
    label="infinite loop",
    on_change=lambda v: raise_(v)
)

def raise_(val):
    if not val:
        raise ValueError()

infinite_loop = mo.ui.switch(
    False,
    label="infinite loop",
    on_change=lambda v: raise_(v)
)

Myles Scolnick•5mo ago

hmm I have no other ideas. We can look into supporting this if there is a good api. Seems like start/stop has been somewhat tried a few times

Akshay•5mo ago

@Georgios Varnavides can you use mo.output.replace?

Georgios VarnavidesOP•5mo ago

hmm, trying to think how exactly 🤔 I'd still need to mutate state for the iteration of the sort x_{n+1} = f[x_n] right?