World: r3wp
[Core] Discuss core issues
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Terry 20-May-2007 [8156] | yeah... I think the conclusion is ... don't worry about the number of bytes (and thus mem) when using plain integers with my index block, as it's much smaller than the dictionary anyways.. and unless Im shown otherwise, the crawling of it (find/ foreach, append) should be about as fast as any other method, right? |
Anton 20-May-2007 [8157] | It should be faster and simpler to just use integers. When you want to cut down the size of your 2 million integers (=30MB), you can then look at implementing 3-byte integers packed in a binary. |
Terry 20-May-2007 [8158] | exactly |
Anton 20-May-2007 [8159x2] | Here's a couple of conversion routines. |
struct: make struct! [int [int]] none ; convert integer -> 3-byte binary integer-to-3-byte-binary: func [integer [integer!]][ struct/int: integer copy/part third struct 3 ] ; convert 3-byte binary -> integer binary-3-byte-to-integer: func [int3 [binary!]][ struct/int: 0 ; just make sure all bytes are zero change third struct int3 struct/int ] ; test my-bin: integer-to-3-byte-binary 2000000 ;== #{80841E} my-int: binary-3-byte-to-integer my-bin ;== 2000000 | |
Terry 20-May-2007 [8161x3] | ok.. that's cool.. thanks |
Even though each integer uses 16 bytes, there's some compaction by using the smallest integers with the most commonly used dictionary strings | |
I'll add these functions to the dictionary.. dict: [{integer-to-3-byte-binary: func [integer [integer!]][ struct/int: integer copy/part third struct 3 ]}] now whenever i want to use that function.. i can represent it with a single integer.. ie: do pick dict 1 | |
Oldes 20-May-2007 [8164x2] | Terry, I would not make own binary storage as there should be new datatype dictionary! in R3 which is exactly what you need... if I understand it well |
I cannot see hash! in this list http://www.rebol.net/r3blogs/0076.html so it will be probably replaced | |
Terry 20-May-2007 [8166] | and that could be reduced further.. dict: [ {fetch: func [index][do pick dict index]} {integer-to-3-byte-binary: func [integer [integer!]][ struct/int: integer copy/part third struct 3 ]} ] do pick dict 1 fetch 2 my-bin: integer-to-3-byte-binary 2000000 |
Oldes 20-May-2007 [8167] | The new vector! datatype will be usefull as well to store large block of same data type |
Terry 20-May-2007 [8168] | Im happy with R2 ;) |
Oldes 20-May-2007 [8169] | yes... you can make it in R2 using index: [1 2 3] and for R3 you just replace: index: make vector! [integer! 24 [1 2 3]] |
Terry 20-May-2007 [8170x3] | Now as for compressing the dictionary.. it seems that smaller strings grow with compression? |
>> a: compress "a" == #{789C4B04000062006201000000} | |
>> a: compress "aaaa" == #{789C4B4C4C4C040003CE018504000000} >> a: compress "aaaaa" == #{789C4B4C04020005B401E605000000} | |
Oldes 20-May-2007 [8173x2] | compress is uzing zlib compression... just insetad of checksum at the tail (last 4 bytes) is used size of the source string |
the size is used to make a result buffer for decompress: >> decompress rejoin [#{789C4B4C} #{04020005B401E6} #{00000000}] ** Script Error: Not enough memory >> decompress rejoin [#{789C4B4C} #{04020005B401E6} #{FF000000}] == "aaaaa" | |
Dockimbel 20-May-2007 [8175] | Terry, your 'integer-to-3-byte-binary conversion function is dependent on platform endianness (third struct! gives you an endian-dependent result), watch out for that. |
Anton 20-May-2007 [8176] | You can blame me for that, I wrote it quickly. |
btiffin 21-May-2007 [8177] | Terminology question; I know I could probably RTFM, but sometimes Ask A Friendly Human is more fun. What is the correct terminology for the global REBOL context. I'm describing (or trying to at least) the parse dialect "copy" versus the REBOL "copy". Is there a one word term for the "no context" context? Or is the REBOL global namespace good enough (and not too confusing to new rebols)? |
Anton 22-May-2007 [8178] | Yeah, we all call it the global context. |
btiffin 22-May-2007 [8179] | Thanks Anton. |
Jerry 22-May-2007 [8180] | Is there a function which can flat a block. For example, >> FLAT [ 1 2 [ 3 4 ] 5 6 ] == [ 1 2 3 4 5 6] |
Graham 22-May-2007 [8181] | probably not what you want ... >> to-block form [ 1 2 [ 3 4 ] 5 6 ] == [1 2 3 4 5 6] |
Chris 22-May-2007 [8182] | flatten: func [block [any-block!]][ parse block [ any [block: any-block! (change/part block first block 1) :block | skip] ] head block ] |
Henrik 23-May-2007 [8183x2] | and with greater speed but less accuracy: >> load form [1 2 [3 4] 5 6] |
and now I should of course have read what Graham posted... | |
BrianH 23-May-2007 [8185] | Don't assume that the parse is slow - you may be surprised. |
Anton 23-May-2007 [8186] | Yes, and I wouldn't recommend the LOAD FORM way, it looks too brittle. |
Henrik 24-May-2007 [8187x2] | does SORT/COMPARE not work in combination with /SKIP? it seems to happily ignore /SKIP here. |
seems that using /ALL does not help. | |
Gregg 24-May-2007 [8189] | >> b: [1 2 3 4 5 5 4 3 2 1 7 6 5 4 3 3 4 5 6 7] == [1 2 3 4 5 5 4 3 2 1 7 6 5 4 3 3 4 5 6 7] >> bb: sort/compare/skip copy b 2 5 == [1 2 3 4 5 5 4 3 2 1 3 4 5 6 7 7 6 5 4 3] >> bb: sort/compare/skip copy b 4 5 == [5 4 3 2 1 1 2 3 4 5 7 6 5 4 3 3 4 5 6 7] |
Henrik 25-May-2007 [8190] | what if the record size is 2, consists of a binary and an object and you want to sort on a value in the object? |
Sunanda 25-May-2007 [8191] | Here's one way -- though it assumes (for simplicity) that the binary is a string of equal length in all keys: data: reduce ["z" make object! [key: 1] "y" make object! [key: 2] "z" make object! [key: 2]] sort/all/skip/compare data 2 func [a b][ return (join a/1 a/2/key) < (join b/1 b/2/key) ] probe data |
Henrik 25-May-2007 [8192x5] | hmm... funny, I did exactly that code, but it would never recognize the b object in the compare function. will have to try again... |
oh wait a minute. I see now :-) | |
I guess I don't after all. I still can't get it to recognize 'b. If I try to probe 'b inside the function, sorting just stops. probing 'a works fine. | |
and the block checks out fine. it is properly arranged. | |
found the bug. (and I need more coffee) | |
Sunanda 25-May-2007 [8197] | There were problems with using all three refinements [ /all/compare/skip ] together in earlier versions of REBOL. I believe they are fixed now. |
Henrik 25-May-2007 [8198] | I think the compare feature is just a bit underdocumented. |
Rebolek 25-May-2007 [8199x2] | Script error: REPLACE has no refinement called ONLY |
I can use CHANGE/ONLY FIND ... What do you think, skould I RAMBO it as a wish? | |
Henrik 25-May-2007 [8201] | rebolek, yeah, I think it would make sense to have that. |
Rebolek 25-May-2007 [8202] | It's mezanine, so I'll try to figure out some fix and post it. |
Henrik 25-May-2007 [8203] | cool |
Rebolek 25-May-2007 [8204x2] | Hm, was easier than I thought :)) |
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