there are some tech issues in this video and some others, blank sections , please fix it. you are GREAT at teaching and i really hope to see more stuff that u can teach and make more sense
It's an electronic blue-board. He writes on it regular, and the board then superimposes a video of him over a background in reverse. Pretty neat. You can tell it's reversed by looking at the buttons on his shirt. I, on the other hand, back when I worked for NORAD in the Cold War days, I actually had to learn to write backwards on a plexiglass window with a grease pen, so the officers on the other side could see what I was writing in normal digits. heh
Radix sort is just beautiful. I didn't know that in practice it is not a very good method. Always in the sounds of sorting videos Radix is the showman and I always believed that it was actually a good sorting method.
Actually, it is very fast if you optimize it well. The reason for that is, an insertion inside an array is considerably faster than a comparison. In fact if we want to optimize it for speed, then what was done on the video: 1. take an array of numbers and sort them to boxes 0-9 2. take the boxes and move their sorted contents back to the beginning array 3. repeat the step for every digit is speed inefficient, because step 2 doesn't contribute in sorting at all. What he'd need to do in order to achieve the highest speed is this: 1. take an array of numbers and sort them to boxes 0-9 2. take the boxes and sort their contents inside another set of boxes 0-9. 3. repeat step 2 for each digit However, it is not robust. 1. This procedure is highly speed efficient, but it's not memory efficient. For instance, in order to achieve the highest possible speed, you need 2x boxes 0-9 and each of the boxes has to be the size of n, where n is the amount of elements you're sorting. So in this video the person was sorting five elements, which means he'd need 20 arrays of length 5. If you are sorting 100k elements, you'll need 20 arrays of length 100k. Which is tremendously memory inefficient. 2. It is not a comparison based sort, hence it is not a good algorithm for almost sorted arrays.
@@poryg5350 You can speed it up further by NOT copying the key values into bins, but instead counting how many values belong to each digit (like a counting sort) then using these counts to calculate the start position for each key digit in an output array. Once you know where in the output array each sub list is going to start, you make a second pass through the input and distribute values directly into the output array. Sure, that requires a second pass through the input, but you can speed that up by not using base 10 digits but instead using base 16 digits which can be rapidly found using shift and mask operations. Now you simply need enough memory for a second size N array, plus the trivial amount needed for the counters. Once you've finished sorting the list on the first hex digit, you just swap the pointers around so that the output array becomes the new input, and and the other array becomes the new output.
he was erasing so the glass so they blacked out that screen time and did you miss some part no i dont understand the issue here dope explanation by the way
dude all the vidoes i have watched.. that black screen stuff only happens here, come on it cant be that difficult to handle it if everybody else can...
@@twerkyfingers Ok, I had to watch another video of his to verify, but his earring that is usually on his right is shown on his left here. Also, most men's button-up shirts follow the "buttons on the right" convention, and here, his shirt buttons on are the left.
Video goes black more than once. _function radixSort(array) {_
_// maxNumberOfDigits is 4 for [5, 1048, 23, 9]_ _// because 1048 as 4 digits_ _let maxNumberOfDigits = ( Math.max(...array).toString() ).length_ _for (let i = 0; i < maxNumberOfDigits; i++) {_ _let buckets = createBuckets()_
_// loop over items and place into buckets_ _// accordingly to the power of ten under examine_ _for (let j = 0; j < array.length; j++) {_ _let number = array[j].toString()_ _// reverse number to read power of ten as left to right_ _// if at current power of ten there's no digit (e.g. 5 as no tens) put it into bucket 0_ _let digit = [...number].reverse()[i] || 0_ _buckets[digit].push(number)_ _}_ _// flatten buckets into array_ _array = concatBuckets(buckets)_ _}_ _return array_ _}_
I don't like this sort because it is redundant. You keep moving a number you've already bucketed once. There should be a sort where you do basically this, but you zero left-pad all numbers to the length of the longest number, then do the sort the other way, from most to least significant. Then lose the leading zeros at the end.
Don't forget that in a computer, all unsigned integer values are already zero padded to the left, because in practice they're stored as 32/64/128 bit values. No practical radix sort algorithm should ever use base 10 digits - base 16 is much faster since you can extract each digit using the very fast shift and mask operations to isolate four bits from the key. Have a look for videos which combine a radix sort with a counting sort. That means there's no longer any need to have specific "buckets" for each digit. You can move values directly from the input array to the correct place in an output array at the price of having two passes (a counting pass and a moving pass). Yes, it is possible to start from the most significant digit, but that actually creates 10 (or 16 if you're working in hex) sub-lists, each of which has to be separately sorted, presumably using form of recursion. It can be done, but I think it's going to be messy.
Sort obviously occurs in a black hole at certain points.
hhhhhhh
@@zoomandreview4008 hhhhhhhh?????
heavy stuff
f
I was looking for that comment sir !
Video goes black in the middle.
Basically what happens is he sorts the new lists based on the tenths, then hundredths and so on :)
Why does the video blank out in the middle?
That's the part where the topless dancing girls appear. You need to sign up to Patreon to see them.
"Well, I completely fucked up the video. Entire chunks are missing. Let's upload it anyway."
compared to many videos discussing the radix sort, this is the best ,most perfect one. Thank you so much
even with third of the video missing...
Awaiting the scary scream after the full silence :)
😀
Čau dědo, miluju tvojí torbu
there are some tech issues in this video and some others, blank sections , please fix it.
you are GREAT at teaching and i really hope to see more stuff that u can teach and make more sense
I see some SORT of Black outs, could you please sort those black outs for another occasion? Thanks so much
Thank you! I am ADHDer trying to understand all this for my masters in data science and your videos most helpful. Subscribed
thanks for the help, video has a part where it goes dark..around 2:17
I also felt this :/
Loved the explanation. Surprised by how easily you write in reverse (super legible too!) !
It's an electronic blue-board. He writes on it regular, and the board then superimposes a video of him over a background in reverse. Pretty neat. You can tell it's reversed by looking at the buttons on his shirt. I, on the other hand, back when I worked for NORAD in the Cold War days, I actually had to learn to write backwards on a plexiglass window with a grease pen, so the officers on the other side could see what I was writing in normal digits. heh
@@robertzeurunkl8401 why didn't they just give every officer a mirror? So you can just write normally.
@@sofiruldanatriya3079 😊😂🤣
@@robertzeurunkl8401 it's not electronic, he is writing on glass, then the video is reversed
@@twerkyfingers Did you notice how he's behind the glass? ;-) I should have noticed that.
Radix sort is just beautiful. I didn't know that in practice it is not a very good method. Always in the sounds of sorting videos Radix is the showman and I always believed that it was actually a good sorting method.
Actually, it is very fast if you optimize it well. The reason for that is, an insertion inside an array is considerably faster than a comparison. In fact if we want to optimize it for speed, then what was done on the video:
1. take an array of numbers and sort them to boxes 0-9
2. take the boxes and move their sorted contents back to the beginning array
3. repeat the step for every digit
is speed inefficient, because step 2 doesn't contribute in sorting at all.
What he'd need to do in order to achieve the highest speed is this:
1. take an array of numbers and sort them to boxes 0-9
2. take the boxes and sort their contents inside another set of boxes 0-9.
3. repeat step 2 for each digit
However, it is not robust.
1. This procedure is highly speed efficient, but it's not memory efficient.
For instance, in order to achieve the highest possible speed, you need 2x boxes 0-9 and each of the boxes has to be the size of n, where n is the amount of elements you're sorting. So in this video the person was sorting five elements, which means he'd need 20 arrays of length 5. If you are sorting 100k elements, you'll need 20 arrays of length 100k. Which is tremendously memory inefficient.
2. It is not a comparison based sort, hence it is not a good algorithm for almost sorted arrays.
So you can use it freely in cases where memory is not an issue. It will serve you well. But if you need memory efficiency, shell sort is much better.
@@poryg5350 You can speed it up further by NOT copying the key values into bins, but instead counting how many values belong to each digit (like a counting sort) then using these counts to calculate the start position for each key digit in an output array. Once you know where in the output array each sub list is going to start, you make a second pass through the input and distribute values directly into the output array. Sure, that requires a second pass through the input, but you can speed that up by not using base 10 digits but instead using base 16 digits which can be rapidly found using shift and mask operations. Now you simply need enough memory for a second size N array, plus the trivial amount needed for the counters. Once you've finished sorting the list on the first hex digit, you just swap the pointers around so that the output array becomes the new input, and and the other array becomes the new output.
Video keeps cutting out with no picture of sound.
the video goes black but seeing how the bins work was really helpful
i had mini heart attack for second right there :)
You done a great job, sir, your lecture is so understandable and your teaching style is amazing sir
Wer ist noch wegen AD hier? 😂
he was erasing so the glass so they blacked out that screen time and did you miss some part no i dont understand the issue here dope explanation by the way
it actually does skip a bit, but you can fill in the context. it's also 2021, video editing exists and could have been used before posting this
wow he writes it mirrored?
it's not mirrored, he is writing on glass, then the video is reversed/mirrored
Super helpful. Thank you Sir!
dude all the vidoes i have watched.. that black screen stuff only happens here, come on it cant be that difficult to handle it if everybody else can...
its pretty simple to figure out whats happening during the blanks lmfao
@@kidmash541 I dunno, man. I failed "black board" in college. ;-)
Wait, he has to write mirrored so we see it unmirrored
it's not mirrored, he is writing on glass, then the video is reversed/mirrored
@@twerkyfingers Ok, I had to watch another video of his to verify, but his earring that is usually on his right is shown on his left here. Also, most men's button-up shirts follow the "buttons on the right" convention, and here, his shirt buttons on are the left.
He really dosent want to give us the answers.
I got it! The real trick happens during blackouts
Wait, is he writing mirrored? What a hero
bruh
Great video for time and detail
... you couldn't just do a jumpcut??
this is good
Video goes black more than once.
_function radixSort(array) {_
_// maxNumberOfDigits is 4 for [5, 1048, 23, 9]_
_// because 1048 as 4 digits_
_let maxNumberOfDigits = ( Math.max(...array).toString() ).length_
_for (let i = 0; i < maxNumberOfDigits; i++) {_
_let buckets = createBuckets()_
_// loop over items and place into buckets_
_// accordingly to the power of ten under examine_
_for (let j = 0; j < array.length; j++) {_
_let number = array[j].toString()_
_// reverse number to read power of ten as left to right_
_// if at current power of ten there's no digit (e.g. 5 as no tens) put it into bucket 0_
_let digit = [...number].reverse()[i] || 0_
_buckets[digit].push(number)_
_}_
_// flatten buckets into array_
_array = concatBuckets(buckets)_
_}_
_return array_
_}_
tank u, lub the cuntent
I don't like this sort because it is redundant. You keep moving a number you've already bucketed once. There should be a sort where you do basically this, but you zero left-pad all numbers to the length of the longest number, then do the sort the other way, from most to least significant. Then lose the leading zeros at the end.
Don't forget that in a computer, all unsigned integer values are already zero padded to the left, because in practice they're stored as 32/64/128 bit values. No practical radix sort algorithm should ever use base 10 digits - base 16 is much faster since you can extract each digit using the very fast shift and mask operations to isolate four bits from the key.
Have a look for videos which combine a radix sort with a counting sort. That means there's no longer any need to have specific "buckets" for each digit. You can move values directly from the input array to the correct place in an output array at the price of having two passes (a counting pass and a moving pass).
Yes, it is possible to start from the most significant digit, but that actually creates 10 (or 16 if you're working in hex) sub-lists, each of which has to be separately sorted, presumably using form of recursion. It can be done, but I think it's going to be messy.
@@mandolinic Exactly! Well said.
It's San Diego State, what do you expect? The lack of care put into this video reflects the quality of education you get there.
🥰
W prof