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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。
- r5 W3 F4 A0 e' Gnetlogo自带的social science--traffic grid这一例子当中,8 P4 V. P$ K4 }2 J
globals
: }8 q/ H  N0 R& |[, j, l$ K# j2 ?. {- E: O
  grid-x-inc               ;; the amount of patches in between two roads in the x direction- ~  f; f' p! c1 p" T: w
  grid-y-inc               ;; the amount of patches in between two roads in the y direction7 U/ B2 _8 n, r0 C* L3 M% `6 X% e
  acceleration             ;; the constant that controls how much a car speeds up or slows down by if5 l, X0 _. k3 ]1 z7 U
                           ;; it is to accelerate or decelerate
5 _# y. Q! T1 N0 d7 A  phase                    ;; keeps track of the phase8 y) F( M  _0 E% J5 d
  num-cars-stopped         ;; the number of cars that are stopped during a single pass thru the go procedure
. X. Z. X' R) H0 {. `3 n  current-light            ;; the currently selected light+ J) u# H/ w. B3 p. R

7 X5 w0 J2 {; m4 O( B" ]  ;; patch agentsets: y; [: W" W/ P+ E2 ^
  intersections ;; agentset containing the patches that are intersections8 I, F7 P! P: w4 y  N9 b1 i7 A
  roads         ;; agentset containing the patches that are roads
# U) B# K. z5 ]* u/ F]" L/ `6 V* T6 w( }
5 e$ i- f' W  J7 _/ S! s' d
turtles-own
, k" u, f6 h% @4 M- _( E( w$ n[5 Q& r% x0 c& W1 `
  speed     ;; the speed of the turtle* W, o- `# R& u; k8 ~, o. q( v% m
  up-car?   ;; true if the turtle moves downwards and false if it moves to the right
' F2 L/ g& t/ A/ f. `, ]* A' v# I9 o  wait-time ;; the amount of time since the last time a turtle has moved
3 R4 O9 x3 b2 k  j/ i5 e% y/ W]
$ Y8 z! N& K+ H: V  S5 C% g. ?+ R7 I: p( O$ O4 ]  k+ l
patches-own
9 ], Y0 N8 V& ~+ s" q[0 B# V6 k& F. W
  intersection?   ;; true if the patch is at the intersection of two roads
# W. [  A  f% U1 i  green-light-up? ;; true if the green light is above the intersection.  otherwise, false.
6 _1 Y" P: y9 X  l                  ;; false for a non-intersection patches.
% E, _/ [8 E, @7 w* v9 G7 w4 \, O  my-row          ;; the row of the intersection counting from the upper left corner of the
4 M0 J9 E! @) E7 |4 u6 c. [, H7 B! h                  ;; world.  -1 for non-intersection patches.  U" j) A& x- U
  my-column       ;; the column of the intersection counting from the upper left corner of the
" d* l! P. X/ P# n1 v' D4 ~- n                  ;; world.  -1 for non-intersection patches.* {- R3 f# ~  x5 p( |3 A
  my-phase        ;; the phase for the intersection.  -1 for non-intersection patches.; I$ m9 V; ^* a% n# a
  auto?           ;; whether or not this intersection will switch automatically.
/ r* J" |1 W3 h# p  C  Y' Q& X' ^                  ;; false for non-intersection patches.
; R9 B" c& r$ N& J2 D]" ?0 {" Y* N/ d

& S' b% J3 K( {# U. x7 n/ L2 k5 U4 s+ X4 O+ W' ?/ {) T5 S+ _2 b
;;;;;;;;;;;;;;;;;;;;;;
8 o1 ]; F* E; b+ S* C;; Setup Procedures ;;, A- s, J0 `* O6 `% i# t% b* s
;;;;;;;;;;;;;;;;;;;;;;, w& y: e: }7 L, w( m* D: q' C, p

# _( A: ^: V; w" \; Q& k+ d;; Initialize the display by giving the global and patch variables initial values.
% F$ e0 ]/ `5 j8 P& O4 e;; Create num-cars of turtles if there are enough road patches for one turtle to
" k% ?$ i  p7 i0 z  `;; be created per road patch. Set up the plots.
* E& a3 y% R; B( [* ito setup
: t6 r- r  E' I! p  ca8 D7 R5 ~' j- A" N" O. B  H" O3 x
  setup-globals
4 q* e1 @( q) l1 [5 ~
) x' D7 ?' [. V/ j: a  ;; First we ask the patches to draw themselves and set up a few variables# A7 R& q; {( y3 M% X5 X
  setup-patches' S# [/ p" c/ h4 o
  make-current one-of intersections
7 ]* \2 k8 R; T" f" j  label-current
- E' K9 r3 G- D  }- K  e# F9 q) e7 U' M
  set-default-shape turtles "car"- y- q( e4 A% W; }( J7 a

9 K6 o3 l1 Q5 V/ N5 l  if (num-cars > count roads)
- @+ L) l% }8 U1 P1 ^) W1 ~3 {  [7 q% q) P, H: t, c
    user-message (word "There are too many cars for the amount of "
# d" ~% D! ?1 m  N; J; o                       "road.  Either increase the amount of roads "4 l7 a# `+ e. k- V$ T
                       "by increasing the GRID-SIZE-X or "4 Y. S, A3 A) x5 ?& @; _4 K
                       "GRID-SIZE-Y sliders, or decrease the "
1 V. M( }: P+ ^$ y% B; Y, I                       "number of cars by lowering the NUMBER slider.\n"& \$ E+ R. D: I9 D, g
                       "The setup has stopped.")4 ~: ~/ M, m. J* d# h+ P7 |
    stop4 K8 P# P  f8 _7 ]* ^- V7 J
  ]& R* K0 n# T& ^9 R+ g
/ m! V3 l# `) o( J, c& ^8 X  P
  ;; Now create the turtles and have each created turtle call the functions setup-cars and set-car-color5 a$ Q( k. g% L1 L+ l6 Q# g6 o- a
  crt num-cars' @, C' i/ Q" d
  [) {1 {8 A. }; j' @' V
    setup-cars) k, D5 z0 m6 O& p
    set-car-color
% _: ~2 t  i$ P4 h3 C# P2 j    record-data
$ s' X; X6 ?! }0 t' J  ]
% z; v& {) C  z0 s* j' h( J
5 \( t6 {% j# Y- Z  ;; give the turtles an initial speed+ w8 F# ~+ s6 W' }
  ask turtles [ set-car-speed ]& N% {5 O  P4 k  g0 d( d

- F4 a8 W( a# Q; ^3 ^4 ]. Q! A! k/ t  reset-ticks" f" X4 u6 {+ T
end& ?6 c' ~* |) E4 c' g9 Z* ^% U

8 w6 B+ }. T0 n1 Y;; Initialize the global variables to appropriate values3 r" e. K2 v! w* D& u( ]) ?
to setup-globals. b+ |$ M2 |- E/ I8 }8 @7 V6 l5 [
  set current-light nobody ;; just for now, since there are no lights yet# y  D7 w: f0 Z/ D/ T) R
  set phase 0
9 i2 c, F$ e4 O9 d+ g  set num-cars-stopped 0: b, A: A! i+ {0 C; Q1 b  t
  set grid-x-inc world-width / grid-size-x. `+ I6 {! J6 W' ^
  set grid-y-inc world-height / grid-size-y) B5 Z4 |' R, ^/ D/ \' O2 f
4 i( h1 M4 o8 x8 Y0 k9 T
  ;; don't make acceleration 0.1 since we could get a rounding error and end up on a patch boundary/ d$ F2 v* ]# c( Z' Q8 p
  set acceleration 0.099: O5 r& l- t9 t! O
end
4 @; ~$ g+ F  \0 j* S
4 [$ I6 V/ `  j& f" i;; Make the patches have appropriate colors, set up the roads and intersections agentsets,
/ Y5 ~+ w6 f) _& n;; and initialize the traffic lights to one setting3 X2 e4 k0 _% V
to setup-patches
( c0 q- N8 K  B2 C  Q  ;; initialize the patch-owned variables and color the patches to a base-color+ {( ]8 m7 H7 C! i' z
  ask patches
( e! e/ m5 \/ _& A4 X* ~7 |  [6 B* J8 B3 D9 ^( F. L# C& r# g
    set intersection? false
. ]' T) B- f" a& f2 I    set auto? false
9 {+ Y$ m9 x1 k. C" O    set green-light-up? true5 h0 b  V) s: c
    set my-row -1
! y2 H# Z: r1 @* D: f    set my-column -19 P; T# j- |% i+ v8 o
    set my-phase -1
8 Q; ~$ O1 R/ ]- V) g+ T9 h, j    set pcolor brown + 3
# s& a* g# g4 c. W  ]0 D+ l/ O5 f9 E

6 }* \) j- x# E  ;; initialize the global variables that hold patch agentsets
9 G# g& M. z) H# @  set roads patches with+ ]8 x. r7 T# W, a7 z' s; \
    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) or
0 m: r4 [9 i# Y6 L( j% T    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]
  ~4 e) r$ S2 N  set intersections roads with
1 R: C# h8 _8 E1 e. ]* ?% N4 o9 T    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) and' E$ F& `( ?" a  E% m
    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]7 z7 m) K' l% `& o- c2 S& h

/ \: H/ C0 ^2 p0 j$ ]  ask roads [ set pcolor white ]) c2 v5 }2 @2 N
    setup-intersections
+ ]; `& J* y, O* \* @5 ~. c$ f0 tend
( K) f. N2 ~8 B* t" t$ V: V6 K; w其中定义道路的句子,如下所示,是什么意思啊?
. g) u( s. v# H9 Z. d. x set roads patches with
5 S2 p6 g+ }: |1 e0 P  b3 h8 R# k    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) or1 N- A$ C6 Q. d$ c0 h  y
    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]: U5 g4 G) B5 k- B- c5 {
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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