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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。
% O; T& Y. j# c. j5 E$ w& bnetlogo自带的social science--traffic grid这一例子当中,
1 D4 n( G6 G3 l. f! }globals
# A% e, a$ s; o# ?[
: Q+ d4 x9 P. @8 A  grid-x-inc               ;; the amount of patches in between two roads in the x direction' U, t6 G6 a' H8 m, P
  grid-y-inc               ;; the amount of patches in between two roads in the y direction/ m. U# u4 m/ ]9 P  w$ m4 _# B8 b* i
  acceleration             ;; the constant that controls how much a car speeds up or slows down by if
: `& ~- m) |  c                           ;; it is to accelerate or decelerate
1 F/ W, M; q' t1 Y& Y1 N- p  phase                    ;; keeps track of the phase+ J4 W, `$ P6 ~8 P5 M
  num-cars-stopped         ;; the number of cars that are stopped during a single pass thru the go procedure5 \: R" D! r  F
  current-light            ;; the currently selected light
6 Y. X9 K7 R. f3 F9 {" b; ]# A# c
  w& L) Y" c* j9 |9 }  ;; patch agentsets
7 |. D3 B0 K- z; e  intersections ;; agentset containing the patches that are intersections" a1 P1 J% S+ k5 z# b  r1 m) \
  roads         ;; agentset containing the patches that are roads
) H* B! v( k  l5 h0 H" X. ?* K4 x]
# q5 K2 _1 l' V) v2 n; c  }" u5 X( Y5 }( N
turtles-own: ?6 T1 J! f# R* t  s9 Q
[
7 ^1 Z' H9 i7 V+ H  speed     ;; the speed of the turtle
: Z+ y. ^+ C4 c+ u, y3 r  up-car?   ;; true if the turtle moves downwards and false if it moves to the right8 }- p: d0 |! V" t- ~. z' w
  wait-time ;; the amount of time since the last time a turtle has moved! j$ ]3 a* B8 f: G" o
]1 l! f$ d; i* T0 P- P8 H! m
/ ?  h! j) h6 d8 e9 l
patches-own$ U  a1 C( [; _* U8 e
[
7 C' e9 {8 h# b0 t2 D6 U  intersection?   ;; true if the patch is at the intersection of two roads
8 p* L- ?9 q6 K, y( i% i  green-light-up? ;; true if the green light is above the intersection.  otherwise, false.
" {, x" D0 O9 b& I( E! y$ p0 F                  ;; false for a non-intersection patches.6 V% ]9 J  B) d# y0 Q) Z) `
  my-row          ;; the row of the intersection counting from the upper left corner of the1 M5 j" F* L' F
                  ;; world.  -1 for non-intersection patches.
8 w! U# E* V9 h/ }+ p  my-column       ;; the column of the intersection counting from the upper left corner of the  C1 B( H5 e+ U8 T5 X# b* [
                  ;; world.  -1 for non-intersection patches.) o  g$ ~# t4 W) a; t( I7 k
  my-phase        ;; the phase for the intersection.  -1 for non-intersection patches.( ^0 f4 M4 F4 T$ n& j: E
  auto?           ;; whether or not this intersection will switch automatically." _2 y1 T7 D+ w: a$ W( ^
                  ;; false for non-intersection patches.
. M; s) ?) U7 J8 z0 y7 ?]
9 t* h0 e0 [. s  n% U- p. y7 K7 m/ x" }  q, s5 w1 A

( I& E) ^6 _% i+ W8 x) X4 S;;;;;;;;;;;;;;;;;;;;;;8 E* A! T$ S7 C/ H3 m
;; Setup Procedures ;;
; W# n3 X  r7 B" r/ U;;;;;;;;;;;;;;;;;;;;;;
, |9 \2 G+ K$ q: o7 Y) h6 u% V% D2 n: c& t- t: s4 g1 C1 s  }7 Q
;; Initialize the display by giving the global and patch variables initial values., U* A% a& n: @) K& ?* {. P2 |
;; Create num-cars of turtles if there are enough road patches for one turtle to
8 a( b/ @0 f6 t;; be created per road patch. Set up the plots.
; ]9 r2 v2 R6 T3 n' ~! sto setup5 V) R4 f2 X/ z; Q
  ca
, M" X/ K% E5 i& S3 \  setup-globals
2 v$ ^5 B6 V( L8 Z2 J+ y5 x% N; c- t4 ^
. _: k9 K+ T8 B  M8 j+ Z; i+ ]  ;; First we ask the patches to draw themselves and set up a few variables' @2 P0 u6 j* P; c
  setup-patches9 H* n) |* @$ D+ r7 m" ]6 |( R
  make-current one-of intersections
& z' C+ `4 g7 q% j  label-current
  c: \; k7 l) b$ ~2 i' N% O* a, _* X: r
  set-default-shape turtles "car"
, P7 [) \# F) w0 T- ]: U4 [
3 o* s2 @+ k& T" c7 ^* x  if (num-cars > count roads). l& }2 Y& D3 f" v. T: Z3 Y8 G
  [+ Q; I. A2 Z; c3 _4 c8 b0 M  R, P
    user-message (word "There are too many cars for the amount of "
  ?# f8 d/ O. V* [                       "road.  Either increase the amount of roads "+ {% y9 H( G+ N
                       "by increasing the GRID-SIZE-X or "5 i; \" Z  V$ a- r7 }- I
                       "GRID-SIZE-Y sliders, or decrease the "$ b( W+ {/ E! V( t/ k
                       "number of cars by lowering the NUMBER slider.\n"
4 P' ~9 n7 \# Y                       "The setup has stopped.")! T, P9 j- b& D$ Y! `# X- t' x
    stop
9 M2 T% f! h9 }" E1 D. o  ]& H: y3 P! r0 O* \- \+ l5 M: K4 V
( |% X  I- w; H  f
  ;; Now create the turtles and have each created turtle call the functions setup-cars and set-car-color' A, m7 N& @* |$ f$ d, n
  crt num-cars/ I" O- [4 y3 C  L$ j
  [# P$ ^$ o3 o" K! K* ~
    setup-cars
8 l' u4 Q, m% |& `- T: r/ d    set-car-color6 w7 M# W: S9 H1 r
    record-data. K8 H3 N$ b* @  g6 i& O- C
  ]
4 Z3 M3 h5 V/ {, a
" s; e! T# X/ p, G4 q# P% p  ;; give the turtles an initial speed4 a* T! m. }6 c: A6 L+ _
  ask turtles [ set-car-speed ]) i1 j2 e  m5 E- ^$ o% u% V' ~
5 P4 V- f( \3 p2 u
  reset-ticks
! J( Q# B' Q1 }- X4 W% ]8 N! Tend' R0 x8 x# D" u3 ?% l
# Z% R) L# p- g1 F6 G
;; Initialize the global variables to appropriate values
5 O2 y4 ~+ L8 m" f' Hto setup-globals6 x: |; t: n' S1 a; N
  set current-light nobody ;; just for now, since there are no lights yet
% z0 o$ Q" x% ], E( n# I- Y- l  set phase 01 J( O2 O5 p$ c& I
  set num-cars-stopped 0
7 x4 @8 I5 D" A" ?/ H# F  set grid-x-inc world-width / grid-size-x
- E2 \) `8 A* P, K4 z  set grid-y-inc world-height / grid-size-y
/ F: p- Y) k8 K& a. m% V' w; F0 }* v& P& p5 _6 ~
  ;; don't make acceleration 0.1 since we could get a rounding error and end up on a patch boundary
" C& h4 [& b8 l' [3 v# d  set acceleration 0.0996 ^- d/ j5 k3 `. W% a
end
* E) x- R9 p/ C. v5 C& D7 ^# u9 g7 {: ?  a, |
;; Make the patches have appropriate colors, set up the roads and intersections agentsets,
, k1 H. z, C/ `4 b, Z0 };; and initialize the traffic lights to one setting+ Q( E7 X( Y9 k: y+ b3 i3 F$ P
to setup-patches* {- x% y+ r5 W
  ;; initialize the patch-owned variables and color the patches to a base-color: ?* L0 i. h* ?" g1 Y
  ask patches
; W% n) I+ T/ x+ X. e! F  [7 a; t3 k0 A( f) q2 w/ T
    set intersection? false
' [* X' X2 @5 O9 ?    set auto? false
1 y9 a- }0 I( V  p% n' k    set green-light-up? true' P. l# j- P8 v
    set my-row -1$ a. `' [! s  c& ^, C6 Y! T
    set my-column -1" b. c( I9 @9 V  q& g
    set my-phase -1
9 |) l2 q9 a; k# s2 V0 N! K; C1 c    set pcolor brown + 3
: x. i( e' u/ Q* D! ?  ]( S1 o: @$ H$ r8 l1 P
" Y9 s6 h5 t) B2 X( n
  ;; initialize the global variables that hold patch agentsets7 k+ x" w$ J# A& E4 H$ c$ e$ Z
  set roads patches with1 Q: e! R/ |: t8 d# r! `- B
    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) or  P6 O3 F) r7 m7 s, ]. G; I
    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]
4 t7 i# }) ]/ q: ]( [+ C  set intersections roads with9 ]# H: ~& i; g- H. r& ~
    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) and' ]; a/ ]' v" G8 S+ n' s
    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]
4 |9 t) T# i7 h, V6 O2 V; X1 m5 _: j7 S8 ?* [  d5 v1 k
  ask roads [ set pcolor white ]
+ I& ~5 S3 E" c0 }' X    setup-intersections
' ~" ~% T7 V7 k$ r# h2 w! C# Kend- K- c# Y2 ]5 V7 c0 D- [
其中定义道路的句子,如下所示,是什么意思啊?
& d2 H2 W" ]5 K/ b" x% @. h set roads patches with+ O% S/ L' c1 P0 p3 P1 Y
    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) or
) o# J8 W$ d" f/ V    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]
$ B; w* [0 }$ N6 f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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