Geohash: the algorithm inside and out - Part 1
HTML-код
- Опубликовано: 20 янв 2025
- Most videos only show you how to use a geohash-not how to create one. I'm changing that. Geohashes are everywhere. Twitter's "Algorithm" keeps track of location solely with geohashes. Why are they so powerful?
Part 1 of 2
GM Morton's original geohash: dominoweb.drac...
Slides: josiahparry.gi...
Written notes: josiahparry.gi...
0:00 - introduction
![BLACK BAG - Official Trailer [HD] - Only in Theaters March 14](http://i.ytimg.com/vi/Du0Xp8WX_7I/mqdefault.jpg)
Thank you for doing humanity a big favor. Somebody who is uncomfortable with people just accepting things and explaining the concept under the hood. Appreciate it!
This video is well made. I've looked into others and they just confused me. This one and part 2 contain everything you need to understand and implement on your own.
Key points make it easy to understand and how to apply it to the real world. One thing I would add is about corner cases - 2 points very close to each other could end up in a different grid ending with a different last character in hash (I don't think there are other cases?).
Please keep it going and grow the channel! Thank you so much!
i just watched this video start to finish and when i went to subscribe i couldn’t BELIEVE how few subscribers you have. this was really well-made and i have a feeling your numbers are gonna start to take off pretty soon
Thank you, Christopher! If you have any requests for topics, please let me know here or in a github issue :) github.com/JosiahParry/youtube-tutorials/issues/1
less subscribers, maybe because people dont deep dive into concepts
Keep up the good work Josiah. This is fantastic. Hope to see you hit the 100K subscriber soon.
Elegant, well done! I had no idea what was going on under the covers!
wow this was crazy interesting! thanks for explaining this super cool concept so clearly!
You have explained really well..hats off to you. Great work.
super clear ,easy and concise walkthrough. Amazing
This was fantastic! It was an excellent explanation. I'm going to build a geohash function for full understanding. Thanks!
Liked the explanation of this subtle concept. At 11:46, the longitude decimal value used for example is not clear. It is not same as 19, as used in 10:46. Further, at 13:52, the sequence in the video is of 30 bits, in contrast to 32 bits in the audio. I guess we pad extra bits to make a combination of 5 bits for mapping.
Excellent! Very nice explanation of how geohash works.
Great explanation! I am surely going to be a strong hire if they ask this to me in the interview :D
This is a fantastic video!
I'm about 6 mins into the video and I gotta say this is pretty neat.
Very well explained.Thank you
That was wonderful 👍
This question may sound dumb, but want to know so after interleaving the total number of bits are going to be 64, we are splitting that into combination of 5 bits to generate a number which we will then look into BASE32 to get the character, 12*5 =60 , what about the remaining 4 bits if we include that is going to be 13 character long geohash. Am i missing something?
Not dumb! You ignore the last 4.
@@josiahparrywhich 4 bits to ignore? The left most or the right most?
@@Survivor420 right most
Hi Josiah - do we know why interleaving is being done?
The interleaving is done to create a z-coordinate in a z-order curve (en.wikipedia.org/wiki/Z-order_curve#Coordinate_values) which helps identify a 2 dimensional position with only one value
can we use redis geo?
sure?
amazing content
2:17 You forgot Plus codes!
Never heard of them! They sound like an S2 derivative of placekeys! Thanks for sharing
@@josiahparryI don't think that's what it's from, but Google Maps uses it. It could be an S2 variant, but I don't know.
i may sound stupid. but i dont undrestand how you truncated it. i mean output is vastly different from input. and other algorithms say that we should interleave the actual binary values
You don't interleave the actual binary values. That tripped me up quite a bit at the beginning. There's a way to do the geohash algorithm using bit-shifting but that's not the way it was initially designed as i'm showing here.
You need to create the binary values your self as described around 10:35. Then after you've encoded longitude and latitude, you interleave those results. Then you truncate the resultant interleaving.
@@josiahparry now i understand. tnx
@@crookeddream dope! lmk if you end up writing it from scratch your self :)
@@josiahparry definitely
subbed, keep up dwag