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[求助] 在看例子时有几个问题看不懂

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发表于 2012-6-20 08:59:43 | 显示全部楼层 |阅读模式
新手,在看netlogo自带的例子时,有几行程序看不懂,希望高手能够指点。3 ?1 t+ I% ?: j. r# d
netlogo自带的social science--traffic grid这一例子当中,
# ?" I& U; \9 {/ Mglobals
. V+ D7 X( }" M/ L% D0 y[! E6 q9 o, j$ X8 ^1 T, {5 R
  grid-x-inc               ;; the amount of patches in between two roads in the x direction# g5 r. D! R& }  P, v! r) \
  grid-y-inc               ;; the amount of patches in between two roads in the y direction
$ L3 z8 W: \+ L( x2 X0 k  acceleration             ;; the constant that controls how much a car speeds up or slows down by if
7 A. l2 U9 X1 D% a6 U; R1 p  P, B                           ;; it is to accelerate or decelerate
' }6 X* S! e" e" [* e  phase                    ;; keeps track of the phase
5 q" B+ v, E. w( i" ^, D+ \  num-cars-stopped         ;; the number of cars that are stopped during a single pass thru the go procedure' n4 Q% H5 z1 W1 H+ u# T
  current-light            ;; the currently selected light* y+ G$ e" P/ B
9 ?1 R, v/ w- a7 E. C' s1 i
  ;; patch agentsets
6 N' C. z# S8 [8 P  intersections ;; agentset containing the patches that are intersections
5 E0 U1 e, h, W( \% |; z  roads         ;; agentset containing the patches that are roads
. Q/ Z; v  t3 B" S! {; D]
" Z2 p2 }! ^4 I1 d, R0 M2 ]) Q* T9 R& C) v
turtles-own$ a2 y+ Y/ B$ t2 s% g9 r3 B
[+ C% L: Y0 k  s4 `* a8 c& ^
  speed     ;; the speed of the turtle8 @. m, z# I' Z" x
  up-car?   ;; true if the turtle moves downwards and false if it moves to the right' C4 N' Y0 R/ K$ n  R
  wait-time ;; the amount of time since the last time a turtle has moved; y* [/ ^0 N. z! ~  d+ Q, `
]
' m( x1 w; `5 r/ L6 ?
6 i% t% ^$ K( h8 Q3 k4 o& j  N0 Y9 Cpatches-own* Y+ |  m) b2 }% j; s. J- `
[
4 r) t) [' k3 F0 i9 k  intersection?   ;; true if the patch is at the intersection of two roads
9 U8 w' o1 ^7 E& N4 _1 S/ k  green-light-up? ;; true if the green light is above the intersection.  otherwise, false.6 f( N7 H& [( d1 U5 J% ?* w
                  ;; false for a non-intersection patches.
7 v$ p4 G4 J* p9 b$ U7 B  my-row          ;; the row of the intersection counting from the upper left corner of the  D* \' ?. K0 C: f3 }: a
                  ;; world.  -1 for non-intersection patches.9 |  G8 {+ Q% S5 ]- g0 w' {6 w
  my-column       ;; the column of the intersection counting from the upper left corner of the
, z& P% q( v" b4 I                  ;; world.  -1 for non-intersection patches.% P/ P. g4 i3 y3 N7 \0 c" `
  my-phase        ;; the phase for the intersection.  -1 for non-intersection patches.
& m1 C. Q' `/ k- x1 F! ]  X  auto?           ;; whether or not this intersection will switch automatically.  o/ V- R* T! n9 q9 Y1 r" F. y
                  ;; false for non-intersection patches.
+ y7 z; a; _: P: N]: w3 L1 A/ X% P/ b, O+ C
/ f2 s  h% I$ Z0 E2 W) J% M
  E+ _* l$ w  B$ N' `( G2 m/ O
;;;;;;;;;;;;;;;;;;;;;;
" h) M( X6 A7 ^) R1 y;; Setup Procedures ;;
$ B1 p4 ?; f3 X. @;;;;;;;;;;;;;;;;;;;;;;5 s+ C/ I# A4 U# F( z& _

, m" n$ ]! e8 T1 b$ E5 k3 {; w4 m;; Initialize the display by giving the global and patch variables initial values.) B3 s( h2 N8 K* }- l' F8 u* U  g
;; Create num-cars of turtles if there are enough road patches for one turtle to
9 o/ S( P- O7 j4 x3 n;; be created per road patch. Set up the plots.; B- p' {: F) p
to setup! I) m7 n1 w; Y& C7 ^
  ca
6 ]) M( a! C2 o2 G& C, a% D% x  setup-globals9 x4 i0 [7 ]: O& g/ m& _5 l# S
! G7 g6 m& D( ^4 O* b9 G2 ~; U
  ;; First we ask the patches to draw themselves and set up a few variables6 i/ J+ x' q2 R# @# i
  setup-patches
3 ~- p* }. o9 U) \) T, ~. c, W& H8 Y  make-current one-of intersections* ]9 {2 I- ~  v( ]/ \) N, J
  label-current
: B; S& h; |; Z- |( E, ~) x- n5 ]- k  o
  set-default-shape turtles "car"
+ X/ ~8 b6 A" {1 l0 ~9 k0 @. G1 h- V( Y3 u3 N2 d/ d
  if (num-cars > count roads)
3 h6 _, t; D% J$ i4 x  [
2 S6 |5 S1 S* b  b    user-message (word "There are too many cars for the amount of "
; C! I( b/ T' t' |$ Y5 ~8 |                       "road.  Either increase the amount of roads "
, o5 A0 f: H+ V% ^* t                       "by increasing the GRID-SIZE-X or "0 g; c) s9 T  q4 k. c# d
                       "GRID-SIZE-Y sliders, or decrease the "
6 d/ A( [# S4 ?5 S; E% |                       "number of cars by lowering the NUMBER slider.\n"- p! Q* A1 N7 |! r- Y; A- x! v
                       "The setup has stopped.")" J5 M+ C6 d- _6 J% d  Q' m; [
    stop) X4 y+ ^! @( v1 Y) R! C
  ]
/ I! {" H) X  R5 m5 P' b' k" H- d7 N# _
  ;; Now create the turtles and have each created turtle call the functions setup-cars and set-car-color  ~9 F% ~; h( ~% _
  crt num-cars6 }: t- d$ B' A) x
  [
1 \! O- {) \. S0 {/ J& E" v    setup-cars
8 r8 T9 V) s" O  {* n    set-car-color
) a- ^5 C5 X, L+ s    record-data
) V  L  j, b3 S" k( s3 D) }; m  ]
/ v4 k: `# O( R! U) W, H6 T
6 A/ E. f8 s0 S7 t! Y7 J  ;; give the turtles an initial speed3 F) G5 f- G9 \/ X& ?% [! H
  ask turtles [ set-car-speed ]5 Y$ ^: Z  p4 n! R$ ^

* q8 \; b3 n3 w8 O0 M8 U  reset-ticks
1 S6 E( |( q& o! W  bend
$ B! j* }7 U0 h) d# O; S% v* S
* d% M( D- H9 l;; Initialize the global variables to appropriate values* h  Z$ ^- v+ \; A
to setup-globals
2 u. p9 p/ C) r. k5 t. W) P  set current-light nobody ;; just for now, since there are no lights yet
, ^. h6 G' G. R1 F" @  set phase 0( A% c: E7 G8 h. w! B
  set num-cars-stopped 0( ?% _7 `+ H# z, l. a6 `; u- n
  set grid-x-inc world-width / grid-size-x
- F7 F) L) ~* o( ^1 }  set grid-y-inc world-height / grid-size-y
* J4 a4 O, q. p$ h; k. D+ }' w
( g. C. k" Z+ B; @* ]' F  ;; don't make acceleration 0.1 since we could get a rounding error and end up on a patch boundary' p5 `8 Y- \3 y) I
  set acceleration 0.099/ t% [/ b( P0 R
end4 S% W+ z6 j1 y  ~6 |) {( i4 ?& d
; ^2 C' x! c8 \9 `; i# _+ a0 G
;; Make the patches have appropriate colors, set up the roads and intersections agentsets,: K, U$ `$ d2 r" t: H. S
;; and initialize the traffic lights to one setting! z4 V* e4 U; e
to setup-patches
* j; Y3 u2 f8 W; [2 z& r  ;; initialize the patch-owned variables and color the patches to a base-color! F. h9 I9 _9 F' G3 v
  ask patches* y; x" W/ [5 X' i
  [
# F4 W/ U6 M2 Y" q# m7 i/ Z    set intersection? false0 c: s/ |3 f* d* J$ F' j
    set auto? false# E; Z& l6 P3 ?9 f
    set green-light-up? true$ i/ ~6 h1 E9 g- x. G* R' ?
    set my-row -1$ a, E+ |6 l* W. ^+ M: ~
    set my-column -1! `% D8 `4 J+ ^+ L) k
    set my-phase -1* K2 E4 N' O: @
    set pcolor brown + 3& o7 T0 V  |. E8 a( i6 R* w6 g$ k
  ]
  M  B; o+ F3 Y! E) L
5 C) l* m, }0 b6 b/ z* c* T0 j  ;; initialize the global variables that hold patch agentsets
. N7 A/ k. a! y# z  set roads patches with
7 ?0 b' O, e3 }. t" y  {    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) or
$ T+ m" _" L) E1 l0 K    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]3 z+ q+ r. H5 g( k' N
  set intersections roads with
  l6 b+ ?2 E1 K    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) and
% X- o5 n' s# i7 \' F# p    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]
! l" E9 L" I' ~: o  f, m/ h9 Y  z: K) t5 [* Z& n7 s# v
  ask roads [ set pcolor white ]+ B+ J* E- R$ D6 O1 m9 h
    setup-intersections7 ]+ P: ^8 R. H
end: A% D+ z. h$ t( d
其中定义道路的句子,如下所示,是什么意思啊?
! D& y- T9 }  d* T set roads patches with
6 M- T: g& K$ `" s$ T0 c' H- S; d    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) or
' O$ q# N! f) K* g+ @    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]
& I) h, u' M1 n谁能帮我解释一下[(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0)是什么意思吗?
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