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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。5 V9 d  q5 _; C' C% d
netlogo自带的social science--traffic grid这一例子当中,( F5 R7 u0 l5 E) T/ t
globals/ J0 A. ~. e# M5 U! ]! ]
[
# V' F9 V2 k7 _" x6 S  grid-x-inc               ;; the amount of patches in between two roads in the x direction
$ V$ m9 D: _4 q  c/ ^  grid-y-inc               ;; the amount of patches in between two roads in the y direction
4 V" D3 o5 Z' c" l3 A  acceleration             ;; the constant that controls how much a car speeds up or slows down by if
1 S3 P6 e3 }1 b) V8 d( q, g                           ;; it is to accelerate or decelerate
* x% o/ {5 S& p$ u) v9 t. m4 H* ^  phase                    ;; keeps track of the phase
; x0 B1 }. v1 s1 Q  num-cars-stopped         ;; the number of cars that are stopped during a single pass thru the go procedure
: I) K8 M! I+ A  current-light            ;; the currently selected light
# l3 k+ h; g' ?3 [# B- J2 d& e4 C( n( q2 X3 N7 F& b
  ;; patch agentsets8 c9 c7 S7 a6 \$ M' }
  intersections ;; agentset containing the patches that are intersections
9 V4 F, A1 {& `& S  roads         ;; agentset containing the patches that are roads
- b# s  Z- ]% J]
4 O5 n( |6 y) n2 K2 J0 C: |; @1 B
+ d( ^) t9 u" b9 L) f; J% Bturtles-own+ |5 R5 U7 G. [2 A2 C: V( i
[
% ~+ B. v$ h2 R) a' x  speed     ;; the speed of the turtle5 H+ _. X. ?4 H
  up-car?   ;; true if the turtle moves downwards and false if it moves to the right, C' a) ]7 t$ d
  wait-time ;; the amount of time since the last time a turtle has moved
/ d+ q( L' c* s+ ^/ M]& t% c  _( H5 l/ B8 ~* f

$ j1 z" f1 Y( v# X2 K2 y( vpatches-own0 {6 M. S$ N* z- _) v
[: J2 I) |; o6 f
  intersection?   ;; true if the patch is at the intersection of two roads
. d; b$ \0 ]5 p9 x; O5 f  green-light-up? ;; true if the green light is above the intersection.  otherwise, false.
; d' P4 z- h- n! F* V7 V' U+ c                  ;; false for a non-intersection patches.
5 H7 W  g& O8 X% l7 d3 @' y  my-row          ;; the row of the intersection counting from the upper left corner of the
) H2 u$ {4 w* n. i3 i) G8 n                  ;; world.  -1 for non-intersection patches.
4 b6 x  x! n* J4 j  \" X1 t& @  my-column       ;; the column of the intersection counting from the upper left corner of the+ ], x) V. |) X% i% J% [
                  ;; world.  -1 for non-intersection patches.
1 l- j# M2 X$ P1 W  my-phase        ;; the phase for the intersection.  -1 for non-intersection patches.
; i$ d, Y( P5 G) F  auto?           ;; whether or not this intersection will switch automatically.! k% w; o) y: L+ B' J2 I
                  ;; false for non-intersection patches.
2 k: S8 U) D8 Z0 {% o+ f: d9 e, {]& m& X; `; Y* r
# Z3 u: I) _6 O/ i0 i

. m& d  K' o1 b;;;;;;;;;;;;;;;;;;;;;;6 ~/ l6 ?3 c; _, _" @* s7 L
;; Setup Procedures ;;+ m+ W* I5 \, p" M' V. R% c
;;;;;;;;;;;;;;;;;;;;;;6 _0 Z1 ?. h) E7 f6 l" ]* D6 {; V

5 z" Z* B. N  ~7 v;; Initialize the display by giving the global and patch variables initial values.4 u3 q7 L# m( w( b2 `- J
;; Create num-cars of turtles if there are enough road patches for one turtle to
* k2 P: e8 s9 B4 q# d( e3 I  ~  n2 W;; be created per road patch. Set up the plots./ [$ f. S8 Y2 l& N* u/ h
to setup# z4 q! C. ^. g1 S: m
  ca3 N& ?8 ?) d: V3 X
  setup-globals
. Q# `, M$ m& E- B- j& Q1 F
9 a  _; P5 }+ ?7 c9 A" K  P0 H  ;; First we ask the patches to draw themselves and set up a few variables% e! K+ L* e' F: K' R
  setup-patches- a9 X" d: I; T5 E
  make-current one-of intersections
; p; l; ~, u9 a8 B1 x1 e' J  label-current
: {8 G: }- {# w! h( N+ _2 B7 Y  n; I& m
  set-default-shape turtles "car"2 T4 h8 M; n& a! _* _

8 J9 p- p9 p1 y( F7 W  if (num-cars > count roads)  A  `. k5 P5 r5 @" G: b
  [
& r" ]0 P2 J, B2 C$ U; n    user-message (word "There are too many cars for the amount of "7 }5 b0 A+ ^  e# E
                       "road.  Either increase the amount of roads "4 j$ w2 \3 V$ j! L
                       "by increasing the GRID-SIZE-X or "
) f5 P+ ^; b1 m( k8 G                       "GRID-SIZE-Y sliders, or decrease the "$ ^* P) a7 u* d/ L2 @' W7 F3 l
                       "number of cars by lowering the NUMBER slider.\n"
: w! H) j* V# g7 a& l! _5 O8 J                       "The setup has stopped.")6 n6 n  k. e; `( @- ?4 {: [
    stop
5 A& u% f/ M' H4 j  ]: k  T( g) u9 }
: {+ w, \6 q; I4 k. A: G1 z
  ;; Now create the turtles and have each created turtle call the functions setup-cars and set-car-color, P- N: l" F$ X8 v
  crt num-cars
7 i- ]$ U% T0 F& L1 C0 [" ]' u* g$ e" S  [5 z/ V* x- c; A5 R+ n& R0 o1 a
    setup-cars0 R' a" K8 {% i
    set-car-color
0 p+ y  b% z2 a6 M/ j( @3 l1 I    record-data
' [! y8 E, ^4 p3 O) d% ~  ]% U& V2 d: y4 n/ f2 q

; c" C2 o* g3 k, j" v  ;; give the turtles an initial speed
! @* A' g" p: d/ g4 Q  ask turtles [ set-car-speed ]
1 d5 L4 N2 Y9 V' \/ \+ Z- b6 L, Q2 l; ^" M$ k4 G. G
  reset-ticks
  b: S: J& W# g; E" {/ pend
3 i: B+ Q$ k; D$ N) \2 E% r, D7 d: z: S# A
;; Initialize the global variables to appropriate values5 j7 P$ J6 u  Z' P) K5 p0 i
to setup-globals
3 R5 N0 b  x* B3 D6 D5 n  set current-light nobody ;; just for now, since there are no lights yet
5 Q& W3 ~* }  j  set phase 0
6 L4 h; _: ^4 W9 ?2 |" ]- V- N( ^  set num-cars-stopped 07 _: a# b- P& s3 q, E' W' D
  set grid-x-inc world-width / grid-size-x4 J% p3 ?& [7 ~% F* P2 [6 T
  set grid-y-inc world-height / grid-size-y( [( V5 b9 K( b8 ^: M5 b
2 F- t, T! l+ S+ m1 y
  ;; don't make acceleration 0.1 since we could get a rounding error and end up on a patch boundary
8 Y. K" F! X, ^! R9 a  I  set acceleration 0.099
" d+ a8 Y+ Y+ D# ?$ w, [, D# Yend: {3 C4 S) ?; h+ i6 j

3 l& f$ |8 X7 w+ S;; Make the patches have appropriate colors, set up the roads and intersections agentsets,
# ^: U; _! t7 |- C- T7 D;; and initialize the traffic lights to one setting% J3 Q* T' F& w, A* ?6 `. M  c
to setup-patches
8 F" `( _# R0 g2 k8 Z) j  ;; initialize the patch-owned variables and color the patches to a base-color/ @% S( X: F& K  u
  ask patches
0 o6 X7 N, J: B( w  [
2 o  g& [9 v% u! [+ A: d    set intersection? false% l7 C5 O5 A) ]0 B* ~
    set auto? false
- f) Q# w0 X0 C/ [    set green-light-up? true
8 Z% v: u# H/ ]" o1 k4 h    set my-row -11 m. y: j  A; {2 c" \) T& S
    set my-column -15 }: \7 g' W8 H  ~4 T9 U
    set my-phase -1
( Q7 t( G2 r7 d  g, t9 [    set pcolor brown + 3
) g6 s( a) q* E  V# j  ]
' p5 w: b, @' f- Z# d0 H! d/ |9 E) h( X7 ^3 j
  ;; initialize the global variables that hold patch agentsets/ h' K" `9 P7 Q2 T
  set roads patches with
" x2 H: q0 w' p1 I, F  R    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) or- i* K; C4 c6 ^% {
    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]. A- q% b. @( o& X0 b0 g: m8 v
  set intersections roads with) }' ?! t, I' [; n. N; k# c
    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) and
" ?3 ?2 p( \: l4 Q5 |    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]8 `1 P# i) v6 W! C

& c. r9 T5 w9 v: V8 L% x  Q0 m% R  ask roads [ set pcolor white ]* U/ C# o# X, [  g
    setup-intersections
& [2 y5 `) ]! ^/ wend- S3 ?. x0 e  a+ ?+ x0 d2 i
其中定义道路的句子,如下所示,是什么意思啊?' z0 A& z  U# ]; C' X
set roads patches with, a. J$ h; O5 c* x+ s  r! e
    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) or
5 O9 J7 b# V7 l, X. B    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]! W7 h, U' m) K/ t0 D
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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