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00:52 Reox: Afternoon. Is anyone available here?
00:52 mithos28: Reox: yep
00:52 Reox: I would like to seek some help regarding scheme and depth first search.
00:52 mithos28: but not its not afternoon where I am
00:52 mithos28: sure
00:52 Reox: haha
00:53 Reox: Hmm just wondering is there any sample on the web where i can learn DFS?
00:53 Reox: It's part of a homework where I need to calculate the 3 shortest distance from 1 node to another node in a graph
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00:55 mithos28: I'm not very knowledgable about where you would find anything like that
00:56 mithos28: my normal answer for most people looking for intro material is HTDP but it doesn't cover search
00:56 Reox: hmm then would it be possible to seek advice from you on how can I go about implementing this?
00:56 mithos28: sure
00:57 mithos28: are you following the design recipe?
00:57 Reox: hmm, may I know what's that?
00:58 Reox: I am quite new to scheme
00:59 mithos28: never mind, it is a phrase used to describe the methodology for approaching a problem. It is used in the racket books/ courses taught from them
00:59 mithos28: What is your problem description
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01:02 Reox: I am suppose to come out with a Train journey planner to suggest travel routes for a given pair of boarding and alighting stations.
01:02 Reox: the train journey planner is to provide 3 shortest distance possible and list the stations out
01:02 Reox: in the sequence of traveling
01:03 mithos28: ok so what format is your input in and what format are you returning your output as
01:05 Reox: My inputs are basically strings eg. boarding station: Beverly rd Alighting station: Kingston Av
01:06 Reox: n then my output suppose to list the stations Beverly Rd -> Church Av -> .... ..... -> Kingston Av
01:08 mithos28: how many inputs will your function have, the number of stations? how are you representing distances between the stations?
01:09 Reox: 2 inputs, boarding and alighting station names. Distance is represented as the number of stations traveled to get to the end point.
01:11 mithos28: how do you know how many stations are between the two boarding and alighting stations, since that doesn't seem to be part of the input.
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01:13 Reox: Ohh, for me, i did a hardcode of the stations available in a subway system using vectors
01:13 Reox: so i would already have defined them in the code
01:13 Reox: I would like to use DFS to go thru the vectors and find 3 possible shortest distance
01:14 mithos28: what data is stored in the vectors?
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01:16 Reox: (vector "current_station" (list "Previous_station" "Next_station))
01:17 mithos28: ok and you have many of these vectors?
01:17 mithos28: how are all of them stored?
01:18 Reox: as many as the number of stations are available on the subway
01:18 Reox: they are stored in overall in another vector
01:19 mithos28: ok. So what is your first approach?
01:19 Reox: (define listofstations ((vector (vector "C" (list "B" "D")) (vector "D" (list "C" "E)) )
01:19 Reox: hmm
01:19 Reox: prompt user to enter his boarding station name
01:19 Reox: n his alighting station name
01:30 mithos28: and then?
01:33 Reox: that's where i would like the DFS to go thru the vectors and find the 3 shortest path available
01:33 mithos28: ok so how do you start your DFS?
01:33 Reox: that.... i have no idea.
01:33 Reox: that's why i am hoping to find some help regarding that.
01:34 mithos28: so in words how does DFS work?
01:35 Reox: starting from the root, it will traverse to the first child node
01:40 Reox: n will go deeper until the goal node is found or till no more child node
01:40 mithos28: what happens when it reaches the first child node?
01:40 mithos28: ok so why are you stuck implementing that?
01:42 Reox: I can do it well in java.. but i still have not grasp scheme's coding well enough to understand n implement it
01:42 mithos28: what are you missing from java that is missing in racket?
01:43 Reox: o.o you mean it's possible to derive dfs from a java sample?
01:44 Reox: i didnt realise that >< haha
01:44 mithos28: idiomatic racket will be different, but you can write java like code in racket.
01:45 mithos28: Once you have it implemented you can then try to make it more racket like in small steps
01:45 Reox: oh ok
01:47 Reox: I will try and see how it gpes =)
01:49 Reox: Thanks for the enlightenment
01:49 mithos28: no problem
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04:11 dingfeng: greetings
04:20 noelw: hi
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05:32 dingfeng: what's ''0?
05:32 dingfeng: (number? 0) > #t
05:32 dingfeng: (number? '0) > #t
05:32 dingfeng: (number? ''0) > #f
05:33 dingfeng: (symbol? ''0) > #f
05:41 rapacity: '(quote 0)
05:42 rapacity: rudybot: (list? ''0)
05:42 rudybot: rapacity: your sandbox is ready
05:42 rudybot: rapacity: ; Value: #t
05:58 dingfeng: =)
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08:52 RacketCommitBot: [racket] plt pushed 3 new commits to master: http://git.io/mrip6Q
08:52 RacketCommitBot: [racket/master] fix contract - Matthew Flatt
08:52 RacketCommitBot: [racket/master] another attempt to fix the build script - Matthew Flatt
08:52 RacketCommitBot: [racket/master] better comment to explain a subtle corner of the expander - Matthew Flatt
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13:05 em: is there a way for racket to 'read in' the data from a .tiff ?  So that a racket program could analyze an image file?
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13:24 samth: em: i don't think there's a TIFF reader in racket
13:24 samth: but you could use the FFI to link to a C implementation
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13:48 em: samth: okay yeah, i'll try to figure that out.
13:49 em: I assume that an image file is in general like a big array of n-tupples with different numbers for things like color, brightness, and whatever for each pixle?
13:50 bremner: em: there is also compression, which complicates things in general (maybe not for tiff)
13:55 em: bremner: i guess you have to first uncompress it then.
13:55 em: tiff readers must do that somehow.
13:55 bremner: em: sure, my point is the on-disk format is not simply an array
13:56 em: oka
13:59 samth: em: the imagemagick ffi example might be useful: https://github.com/plt/racket/blob/master/collects/ffi/examples/magick.rkt
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14:21 em: samth: is there any image format that is particularly raw or easy for racket/scheme to work with? maybe i can just convert tiff to that, if there is such a thing.
14:23 mithos28: em: for a really simple image format you can use pnm, but that may be too simple.
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14:38 em: mithos28: when people do stuff like facial recognition that must involve taking an image file and parsing the data of it somehow.
14:40 samth: em: racket supports a bunch of bitmap image formats already; see http://pre.racket-lang.org/docs/html/draw/bitmap_.html?q=load-file#%28meth._%28%28%28lib._racket/draw..rkt%29._bitmap~25%29._load-file%29%29
14:40 rudybot: http://tinyurl.com/64gzqg9
14:41 mithos28: rudybot: doc get-argb-pixels
14:41 rudybot: mithos28: your sandbox is ready
14:41 rudybot: mithos28: not found in any library's documentation: get-argb-pixels
14:42 samth: http://pre.racket-lang.org/docs/html/draw/bitmap_.html?q=get-argb#%28meth._%28%28%28lib._racket/draw..rkt%29._bitmap~25%29._get-argb-pixels%29%29
14:42 rudybot: http://tinyurl.com/3tht3ex
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14:52 RacketCommitBot: [racket] plt pushed 2 new commits to master: http://git.io/llT4Sw
14:52 RacketCommitBot: [racket/master] clean up the docs for the Planet Cute images - Robby Findler
14:52 RacketCommitBot: [racket/master] adjust the planet cute images so they cooperate with executable creation better - Robby Findler
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15:15 RacketCommitBot: [racket] plt pushed 1 new commit to master: http://git.io/taoMKA
15:15 RacketCommitBot: [racket/master] Avoid spaces and caps in file names. - Eli Barzilay
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15:34 samth: tonyg: you around today?
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16:13 tonyg: samth: hi
16:13 tonyg: samth: I'm at home but, er, telepresent
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16:43 RacketCommitBot: [racket] plt pushed 1 new commit to master: http://git.io/os2jnw
16:43 RacketCommitBot: [racket/master] Fix curried function type parsing without (). - Sam Tobin-Hochstadt
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22:01 RacketCommitBot: [racket] plt pushed 1 new commit to master: http://git.io/_hiTvg
22:01 RacketCommitBot: [racket/master] fix editor refresh problem when line numbers are shown - Matthew Flatt
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