Comment on Programmer tries to explain binary search to the police

• CosmicCleric@lemmy.world ⁨10⁩ ⁨months⁩ ago

  But you will see the event happen though.

  Not with a binary search.

  Yes you will.

  A binary search is just what it says it’s for searching only.

  When you find that moment in time where the bike was there and then the next moment the bike’s not there, then you view at regular or even slow-mo at those few seconds of the bike in the middle of disappearing, and see the perpetrator.

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  • Azzu@lemm.ee ⁨10⁩ ⁨months⁩ ago

    You didn’t get what was talked about here. Re-read the topmost parent comment.

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    • CosmicCleric@lemmy.world ⁨10⁩ ⁨months⁩ ago

      You didn’t get what was talked about here. Re-read the topmost parent comment.

      How do you binary search for two people arriving, one punches the other, they both leave?

      I was responding to this …

      Part of my job is to review security footage for reported incidents.

      If there is a long-lasting visual cue that the event has or has not happened yet (e.g. a window is either broken or not), then a binary search is very useful.

      If the event lasts only a moment and leaves no visual cue (e.g. an assault), then binary search is practically useless.

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      • LUHG_HANI@lemmy.world ⁨10⁩ ⁨months⁩ ago

        Maybe I’m not understanding both arguments here but I’d like to understand. I’ve had to review footage of a vending machine being shaken to release drinks.

        You have no before or after visual clue as to when the event took place. The only indication is when you physically see it happening. The same could be said for an assault. If nothing is changed in the before or after static still how can you pinpoint the incident?

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    • CosmicCleric@lemmy.world ⁨10⁩ ⁨months⁩ ago

      In the same way the OP talks about it …

      You don’t watch the whole thing, he said. You use a binary search. You fast forward to halfway, see if the bike is there and, if it is, zoom to three quarters of the way through. But if it wasn’t there at the halfway mark, you rewind to a quarter of the way though. Its very quick. In fact, he had pointed out, if the CCTV footage stretched back to the dawn of humanity it would probably have taken an hour to find the moment of theft.

      Instead of a bike, you look for the aftereffects of a fight happening (chairs knocked down, tables turned over, etc.). You can even look at how many people congregate around the location of the fight before and after the video as a ‘marker’ to the point of time the fight was happening/just finished.

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      • TheSanSabaSongbird@lemdro.id ⁨10⁩ ⁨months⁩ ago

        You are seriously confused. OP specifically said that you’re fucked if there is no visual cue.

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      • Kialdadial@iusearchlinux.fyi ⁨10⁩ ⁨months⁩ ago

        Your adding things that would allow a binary search work, but the question was in a situation where the only evidence is the conflict itself

        2 guys enter one guy punches the other guy they both leave. Nothing is moved no blood was created,

        you could not use a binary search effectively to duduce when it occurred.

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      • Ardyssian@sh.itjust.works ⁨10⁩ ⁨months⁩ ago

        What about this hypothetical scenario:

        Suppose the objective is to review highway cam footage of the day to verify that a (non-speeding) car with a particular license plate passed by the area / used this route. We know on average cars that drive past this camera only appear for 3 seconds on the footage. How can binary search be used to find the car within 24 hours of footage, if the target car only appears for 3 seconds within the 24 hour span?

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  • ShrimpsIsBugs@programming.dev ⁨10⁩ ⁨months⁩ ago

    You either don’t know what binary search is or you completely missed the context of this conversation

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    • CosmicCleric@lemmy.world ⁨10⁩ ⁨months⁩ ago

      I’m a computer programmer. I know exactly what a binary search is.

      The search is to get you to the point where you can watch the video to see the crime happening, in hopes of indentifying the perpretrator.

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      • SkippingRelax@lemmy.world ⁨10⁩ ⁨months⁩ ago

        Then you missed the point of this conversation

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  • lustyargonian@lemm.ee ⁨10⁩ ⁨months⁩ ago

    Binary search only works on sorted data, i.e. you know which side of the mid point is pointing towards the incident. If the incident leaves no trail, you can’t know whether you can discard the left side or the right side, making it a complicated linear search at that moment.

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    • CosmicCleric@lemmy.world ⁨10⁩ ⁨months⁩ ago

      If the incident leaves no trail, you can’t know whether you can discard the left side or the right side

      There’s a moment where the bike is there, then another when its not. The whole video, either way, will either from the beginning up to the point of theft have the bike there, or NOT have the bike there from the point of theft to the end of the video. The marker is the removal of the bike from the video lens.

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      • starman2112@sh.itjust.works ⁨10⁩ ⁨months⁩ ago

        But the comment you replied to wasn’t talking about bike thefts specifically, it was talking about unspecified situations that don’t leave traces. You responded to someone saying that binary search doesn’t work in situations that don’t leave cues not by arguing against the premise (e.g. “but no such event exists, everything leaves cues”), but by telling them that you simply have to look for the cues from the hypothetical event that didn’t leave any.

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  • null@slrpnk.net ⁨10⁩ ⁨months⁩ ago

    That doesn’t apply to the comment you replied to.

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    • CosmicCleric@lemmy.world ⁨10⁩ ⁨months⁩ ago

      Yes, it does.

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      • null@slrpnk.net ⁨10⁩ ⁨months⁩ ago

        If the event lasts only a moment and leaves no visual cue (e.g. an assault), then binary search is practically useless.

        How?

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• CosmicCleric@lemmy.world ⁨10⁩ ⁨months⁩ ago

  Edit: just collapse this thread and move on. Cosmic Cleric is an obvious troll.

  Screw you, and your gatekeeping censoring.

  I’m replied, saying the comment is not correct, and I gave reason why, which are valid reasons.

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  • starman2112@sh.itjust.works ⁨10⁩ ⁨months⁩ ago

    Your reasons for why they were incorrect about a binary search being useless in situations that don’t leave visual cues is that you can simply look for the visual cues lmao, that’s not valid at all

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    • CosmicCleric@lemmy.world ⁨10⁩ ⁨months⁩ ago

      Your reasons for why they were incorrect about a binary search being useless in situations that don’t leave visual cues is that you can simply look for the visual cues lmao, that’s not valid at all

      I never said they work 100% of the time. I said they work most of the time, which is a true statement.

      An event happens in time, that event has a duration, if you can detect that duration then a binary search works perfectly fine.

      And even after the duration most times events change the environment around them, which stay statically changed, and are detectable.

      So much work to try to Kill the Messenger. Maybe organizations don’t want people to think they work so people won’t demand that they be used, causing more work for them.

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      • starman2112@sh.itjust.works ⁨10⁩ ⁨months⁩ ago

        An event happens in time, that event has a duration, if you can detect that duration then a binary search works perfectly fine.

        And even after the duration most times events change the environment around them, which stay statically changed, and are detectable.

        Right. And when that happens, it’s covered by the second paragraph of the parent comment:

        If there is a long-lasting visual cue that the event has or has not happened yet (e.g. a window is either broken or not), then a binary search is very useful.

        Situations where binary searches aren’t useful are covered in the third paragraph of the comment:

        If the event lasts only a moment and leaves no visual cue (e.g. an assault), then binary search is practically useless.

        You’ve claimed that you disagree with this, but have yet to explain why you disagree beyond saying that there would be visual cues. Except that they’ve already said that binary searches work in situations that leave visual cues. You haven’t explained how a binary search can work in situations that leave no visual cues except by claiming they they would, EXCEPT IF THEY DO, THEN THE PERSON YOU CLAIM TO DISAGREE WITH HAS ALREADY SAID THAT BINARY SEARCHES ARE USEFUL.

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