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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。  q0 a# ~0 j5 h1 k1 Z& k) f* b
netlogo自带的social science--traffic grid这一例子当中,9 L" _' z% K8 U% C; ?( W( I
globals
0 x" M6 O  S* Y7 O  k[0 j5 Z6 Q. ]2 @* H
  grid-x-inc               ;; the amount of patches in between two roads in the x direction- U3 m; V1 l* P1 T6 Y
  grid-y-inc               ;; the amount of patches in between two roads in the y direction
5 ?: [; c4 e2 R2 q  acceleration             ;; the constant that controls how much a car speeds up or slows down by if
6 v# N7 O- E- i2 x9 D0 H                           ;; it is to accelerate or decelerate& B; e% A7 w6 O- y
  phase                    ;; keeps track of the phase# R' U" T  G7 m8 B3 L- g6 K
  num-cars-stopped         ;; the number of cars that are stopped during a single pass thru the go procedure" w' Z  k9 D7 q; C3 X. J
  current-light            ;; the currently selected light* d+ q8 U# |; z& n8 S6 a; N
6 }) C( R8 |/ K4 V0 _
  ;; patch agentsets# y1 R# y9 K& g$ M) m7 k4 @3 i
  intersections ;; agentset containing the patches that are intersections
$ h* R/ L% q4 l6 ?+ B4 r6 E  roads         ;; agentset containing the patches that are roads
) V4 V2 r8 A! N]/ J; \4 {) E5 D( ~0 S/ N( O6 N9 q
. T; e, I/ K0 x" t/ d3 u) h
turtles-own
& R4 S+ c$ ~4 ]0 }# ~2 q[
- a0 g' u* \4 C: ]! l  speed     ;; the speed of the turtle
/ w: P, G. A  S1 d) v3 p7 i1 `8 N  up-car?   ;; true if the turtle moves downwards and false if it moves to the right
# l" r" L( L9 K! Y* z# ?6 `  wait-time ;; the amount of time since the last time a turtle has moved! T: n* C( b, l  U
]: R" g# |1 E  Y: G$ S5 R  g
2 p7 h' [- M1 A/ e
patches-own9 e* h& M0 Z4 Q: c6 y
[
9 p3 F4 k2 e' g. `  intersection?   ;; true if the patch is at the intersection of two roads, ~4 g3 J8 P) x5 _0 f
  green-light-up? ;; true if the green light is above the intersection.  otherwise, false.
. }  l  T) o; l$ _6 ]* R8 C( V: e- ~                  ;; false for a non-intersection patches.
3 y3 S3 B8 Z8 Q( h6 x, v- p' a5 w. e0 \  my-row          ;; the row of the intersection counting from the upper left corner of the* B+ {5 R/ ]& B1 h; Y: F- O
                  ;; world.  -1 for non-intersection patches.
4 x8 P1 m8 \. J. N* s: B  X  my-column       ;; the column of the intersection counting from the upper left corner of the
$ ?: h& R1 _; w, s$ {$ _  b$ C  A& w% V                  ;; world.  -1 for non-intersection patches.
% K5 o, M7 \. I0 t4 E  my-phase        ;; the phase for the intersection.  -1 for non-intersection patches.0 t8 ^; F: p+ t0 i) Z+ ]- V
  auto?           ;; whether or not this intersection will switch automatically.! P3 F2 A. {% x4 W6 ^
                  ;; false for non-intersection patches.
+ R. `# ~# p8 Z* n. H]
9 U7 x8 a/ u5 T6 k( D- ~( S/ m
1 D. d/ D8 H" U" q3 K  Z, p/ E9 b5 ^) a/ l4 `
;;;;;;;;;;;;;;;;;;;;;;
8 w( h6 n' k: R; B% G;; Setup Procedures ;;
% E& f+ p9 o3 x0 J  y- [;;;;;;;;;;;;;;;;;;;;;;# t. r& }- F8 U( r4 L3 y

9 w: R# z6 d: W" ^& z  k! |7 X+ p;; Initialize the display by giving the global and patch variables initial values.
1 [  ?- X$ [5 ~; I( t" w;; Create num-cars of turtles if there are enough road patches for one turtle to. f4 g/ q: G; k+ P* Y: f& K# U' _
;; be created per road patch. Set up the plots.- O+ g, A. _' V; i! y( Z
to setup
, K! V" ~: r1 p" w9 ~  ca
/ c8 b9 T9 w1 z/ n5 O. D) g$ V9 M+ L  setup-globals/ p: ]% K# k+ z
4 @- L, P2 |: M* d0 o% P
  ;; First we ask the patches to draw themselves and set up a few variables
/ |  D  V3 g  c! F5 D) o  A  setup-patches
+ r3 K, R* T* K8 c  make-current one-of intersections0 e- X# \4 `' j+ a" ?+ B
  label-current
) T; X$ N( A# |) b. ]
7 E2 q" ?1 R4 W- c+ m5 ]  set-default-shape turtles "car"
6 }# ^5 u5 d+ E* I3 d2 |6 M+ h, G3 Z$ [4 ]2 ~
  if (num-cars > count roads)
( _2 v2 A( c3 o; s; I) _) O  [
, B) M1 w5 w4 R+ {6 H4 [# w    user-message (word "There are too many cars for the amount of "4 K* F' m% ^1 a3 U0 g
                       "road.  Either increase the amount of roads "+ Z# ]- _7 a) b! W. s! G/ ?' Z* I
                       "by increasing the GRID-SIZE-X or "9 k. X% ^9 _& `0 H& Z8 S( {
                       "GRID-SIZE-Y sliders, or decrease the "
# W" x  c+ O/ Z5 K1 ]+ _                       "number of cars by lowering the NUMBER slider.\n"
; e+ X: H" |5 W& X9 x                       "The setup has stopped.")- @8 k; E  ~; E% q# ^. q2 M/ w
    stop
9 Y7 O! f- i. n/ l, S) Y2 P  ]$ W' r1 m  c7 l6 _7 b0 {
! S! D: o1 ?6 j# o
  ;; Now create the turtles and have each created turtle call the functions setup-cars and set-car-color
5 ]( t* c! _- z& W# @  crt num-cars! l* o- w8 M/ e5 Z7 H
  [+ c3 v3 \- e( p2 @9 K; B( M. P
    setup-cars  a; w& D8 r- R
    set-car-color& U% ]  c+ L% s7 Q
    record-data
  l5 d4 R# f3 A8 O6 l, S- ~5 ?  ]* U! _3 L. p& M$ ]: [0 W; A

/ R: Z$ x1 E+ b8 p* r3 c* |" r  ;; give the turtles an initial speed, L- Y( F  i& r
  ask turtles [ set-car-speed ]
/ [% m# X4 K. W* ]% H
0 d/ @6 m3 ?+ i. S  reset-ticks9 Q' T) F: b" U. L; ~# m7 p& ~
end! b# w2 d1 ?" a$ V) A
( M7 H/ q! d5 C  ^
;; Initialize the global variables to appropriate values
% R6 A8 D& ~  m. y- @4 L# m5 Nto setup-globals
; \! N# D! i8 A" s8 W! }  set current-light nobody ;; just for now, since there are no lights yet, D" z* ^) W( G8 G  p
  set phase 03 z8 d; Z5 n+ X5 g( f* F3 W( w
  set num-cars-stopped 0
: S; Q1 y( h( P. {: M7 }  set grid-x-inc world-width / grid-size-x$ r* T) X$ @% k& F
  set grid-y-inc world-height / grid-size-y
/ L7 z- d: [1 G
4 B; d- m8 L9 l) K! p( D/ H4 F  ;; don't make acceleration 0.1 since we could get a rounding error and end up on a patch boundary+ V! r5 M0 b4 M$ Y
  set acceleration 0.099, ~7 I( b6 B, T) ~. ^. \9 A" K: |
end9 g6 g: P$ L* }! i) e* Z
* E% ^! D  c+ N& K- n( }
;; Make the patches have appropriate colors, set up the roads and intersections agentsets," a/ y0 S. X  ]: Q
;; and initialize the traffic lights to one setting7 k% j6 l; P4 h( i# N
to setup-patches8 s6 b: i' g  p
  ;; initialize the patch-owned variables and color the patches to a base-color- |" `- D! k# U7 \9 X1 d% O0 y
  ask patches
* L0 K5 |6 c0 I% r/ _+ @5 J! I  [
9 n" y9 j$ |8 v    set intersection? false3 Y. h( Y6 U% z% D' @& b/ A
    set auto? false5 z9 ~4 p& Z; c2 [( x! R
    set green-light-up? true
- H. M* k( x, c: A3 M    set my-row -1( s& R3 Q: |( M; b9 c5 _  }. q
    set my-column -1& Q+ ^; U1 T1 s9 y" ]- ~. J
    set my-phase -1
. T1 D4 R0 k; W( G    set pcolor brown + 3
, e( |% ^  \* r  ]' }. f/ ]6 P# H8 T( i# ?/ E; E
+ L* Z& p% ~7 i' t* o
  ;; initialize the global variables that hold patch agentsets
2 Y# M; G: ~# z' g9 v  set roads patches with# O/ |* C  I8 q. u
    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) or
& Z6 n# u9 V/ x  i1 S  [    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]& X% o" s( ?8 s. @" X
  set intersections roads with
0 l) w8 b- h! R6 ?( B, \( b9 d    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) and
- g& g2 N3 y4 {4 \6 {, x+ `    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]
. D7 ~8 d& E! [3 n0 r$ z& R! O5 j# o, o( \- b6 d4 A
  ask roads [ set pcolor white ]8 U5 z, f; f- E& s5 D# p  H1 _
    setup-intersections( x6 U6 @9 ]; X$ L- y- ?
end
  X, q5 e# j0 a; M% k$ s其中定义道路的句子,如下所示,是什么意思啊?
9 F* e' m6 J9 U: j* a- K0 G set roads patches with
, x* k( C1 j# Q4 R    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) or! E; ?9 V& m& G9 ~. N
    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]  [3 g5 q$ q/ j8 O: W& z0 k4 U
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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