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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。
  ~0 x% @5 N% a+ I) D- T5 lnetlogo自带的social science--traffic grid这一例子当中,) @, o' J$ b% ]1 n. [
globals
( z. b$ y+ K4 G7 e1 E) c[( b$ e' b$ \; N: K! S& w3 V
  grid-x-inc               ;; the amount of patches in between two roads in the x direction
2 D4 S& U& P" M- {3 T  grid-y-inc               ;; the amount of patches in between two roads in the y direction
2 |, ]# s5 v7 j# m4 d; P  acceleration             ;; the constant that controls how much a car speeds up or slows down by if5 k- T' X/ Y- n# b3 ?
                           ;; it is to accelerate or decelerate- Z# k% w  D) N5 u
  phase                    ;; keeps track of the phase
/ l! u+ |0 N* M. [  num-cars-stopped         ;; the number of cars that are stopped during a single pass thru the go procedure6 c& s6 G+ V- Z( x  n$ c
  current-light            ;; the currently selected light6 T0 M/ k" H2 w' }' V  Q
! Q+ f- n& U- m$ `( W: k3 Z
  ;; patch agentsets
, z& C5 c% l) |9 @3 x) v7 j, U  intersections ;; agentset containing the patches that are intersections
1 A+ b4 j" p/ i" D; C  roads         ;; agentset containing the patches that are roads+ K* Y+ T5 C9 Z/ E2 R3 W# F$ W; L
]2 q. ]" x' \6 s" F6 r- ~  C/ `0 y0 x

* f8 W/ E2 a, Z4 H+ A2 ]8 Oturtles-own
) ^( J0 G6 X2 {[3 |1 `- J7 C$ Y" P0 t3 d# a, Q
  speed     ;; the speed of the turtle3 G$ X3 ~9 g2 i  V4 I$ y
  up-car?   ;; true if the turtle moves downwards and false if it moves to the right
  G; {( {/ U" X0 _# j- I7 x1 b$ W  wait-time ;; the amount of time since the last time a turtle has moved
7 Z3 ^5 ^$ k& u; j) f& {]
; [, L# C. F. W, D* n8 K6 s+ Q  A) _1 c9 V* B- v4 P
patches-own
3 E; l2 J: h6 K3 m[
! c5 P/ H+ \% D. H0 G* ~  intersection?   ;; true if the patch is at the intersection of two roads
( w' J* `* e8 B* Y& g5 c  green-light-up? ;; true if the green light is above the intersection.  otherwise, false.
- L5 w# a' B9 s4 g                  ;; false for a non-intersection patches.
* P/ P. J1 \3 y1 q0 }! t4 M% C3 F7 f  my-row          ;; the row of the intersection counting from the upper left corner of the
9 F1 M; A- `  ^; D; a& V                  ;; world.  -1 for non-intersection patches.1 R2 T" O6 y0 v1 s. M+ e8 J
  my-column       ;; the column of the intersection counting from the upper left corner of the
& @9 u* l' I- C& C8 k. n' J0 C7 |                  ;; world.  -1 for non-intersection patches.+ Y$ V" U; l4 J3 d
  my-phase        ;; the phase for the intersection.  -1 for non-intersection patches.
% k! N3 B; F' J2 t( e  auto?           ;; whether or not this intersection will switch automatically.7 a7 q7 o) _/ g" c6 [
                  ;; false for non-intersection patches.7 g( q% R1 G8 W
]9 L6 Z1 s; U# I% o, [1 G8 R

# }* F5 M% ?1 L; f/ s* J9 L' @4 k  Y6 E
;;;;;;;;;;;;;;;;;;;;;;
* o" g& R5 Q- S/ P0 g! K;; Setup Procedures ;;) Q5 [. e  x' i" @
;;;;;;;;;;;;;;;;;;;;;;. {* d" K7 {: N) Q  D! V. @

# s3 H6 m8 C$ Q4 q" G9 J; w; ?$ V# i;; Initialize the display by giving the global and patch variables initial values.: c6 J" j: Y: |# _& N. Q$ v
;; Create num-cars of turtles if there are enough road patches for one turtle to
& Q, f# f: o' y& q;; be created per road patch. Set up the plots.
8 l" Q( @9 I4 {* J+ y0 Yto setup# A; v* X7 e9 R0 ~+ _
  ca& \7 n2 e6 L7 f; ]$ Y9 v; A
  setup-globals
  B5 V3 x8 r! D1 ]4 _5 _, C0 z2 ?$ ~; y
  ;; First we ask the patches to draw themselves and set up a few variables
  H0 K' i* w) a+ m  setup-patches+ {% Z' F6 n: `5 ?
  make-current one-of intersections
: r8 o6 B& e" Z+ o) C5 E, t  label-current7 S6 o* `5 {0 N
1 [3 w. y* T5 S$ A: A! D
  set-default-shape turtles "car"* h" X. r: ^( R9 P

4 w1 g- I! O1 C5 |9 D  if (num-cars > count roads)
% ~4 f! c* e  q: ~! t  [  G& {  J1 S8 S- v- B3 i1 k
    user-message (word "There are too many cars for the amount of "
1 e1 w7 ]- _' |$ D% b* F                       "road.  Either increase the amount of roads "
' l9 E( q3 N/ r6 e5 ]( P9 ~                       "by increasing the GRID-SIZE-X or "
, `8 c+ H" p9 K1 ~                       "GRID-SIZE-Y sliders, or decrease the "9 U% s7 G, O  ^3 W* X$ a6 M6 Z  L" Z
                       "number of cars by lowering the NUMBER slider.\n"% T1 D: w- y, N; s5 `" A  K' |: f3 ~/ o
                       "The setup has stopped.")
$ P. t% O# `6 |4 S) O    stop
9 C& H; `6 c- a* s! A( }  ]
( t' _" @2 V- q) Z# R1 n7 b1 B5 X. G, e" a# c; L( A
  ;; Now create the turtles and have each created turtle call the functions setup-cars and set-car-color% [; w7 Q9 _1 J0 L/ C; Q
  crt num-cars
- \$ J3 Z, \2 M* g5 F3 R4 ~  [8 D# f& B2 R" @% V6 j1 p3 ?
    setup-cars$ R8 }% R) d$ U# Y' M4 O! V0 A
    set-car-color
) B% F; l* [6 `, c# E    record-data9 E1 ]) w0 R# O' z; l( [5 P
  ]& [: W0 a  Y4 o& {1 T' Q3 |
% Z$ c) ^1 M& S2 f
  ;; give the turtles an initial speed
& u- o2 c8 a. }: b# k! m8 \  ask turtles [ set-car-speed ]
2 ?; p. `' Y! k
' l9 h  ?: k% q7 [2 p  reset-ticks
8 o1 n- z; }/ d( D0 Wend
; T' `5 I2 I( x
' C2 \- |) Z) h;; Initialize the global variables to appropriate values% Z/ m- f, h5 Q% ]4 @# c
to setup-globals
5 ^  C. B# V3 p3 ?, i& H  set current-light nobody ;; just for now, since there are no lights yet: ~: E4 {  B9 M! j7 n/ ~( P
  set phase 0
( u) O/ ^6 d7 ]  set num-cars-stopped 0
# y3 V1 B$ ^1 b9 F  set grid-x-inc world-width / grid-size-x
( n7 B4 {0 j3 i  set grid-y-inc world-height / grid-size-y6 h1 E( [& G: t! G  u  y; B
- z+ ^. l( N) o* A; m; ?, z  e
  ;; don't make acceleration 0.1 since we could get a rounding error and end up on a patch boundary
) _5 M' e) n% z. b1 o  set acceleration 0.099
/ A( ~5 ~1 g' u+ C& K# G  M9 a. vend
, B) N! j& x; X6 U. N; S# c2 R
;; Make the patches have appropriate colors, set up the roads and intersections agentsets,6 V* B0 N6 [% d% G5 l% w  z
;; and initialize the traffic lights to one setting
  t3 D0 @/ |  ~7 \( i- Qto setup-patches5 e, S6 @8 e2 l
  ;; initialize the patch-owned variables and color the patches to a base-color, D1 Q; x9 ~8 H7 L
  ask patches+ y( c9 `6 U3 C# i  f/ Q
  [
/ p* A5 j% z; _    set intersection? false  j# p; q, z2 G2 \# v
    set auto? false4 t- M( Q' M9 h5 y; z2 V* w) I6 i
    set green-light-up? true* G* Y! U! y& B
    set my-row -1
& l3 s' ^/ ]3 G3 ]! X# q1 h# C    set my-column -1
) P8 @% r: c) f! {. N2 d    set my-phase -1/ O+ z0 T5 Y9 k, e
    set pcolor brown + 3
. A) \# ~, h$ ~; F) r  ]/ n: k. T: k* N" J1 {1 d- q6 a6 O2 s' D

) p, L$ n8 l6 J. F' ^$ t, ?- ]( k/ o  ;; initialize the global variables that hold patch agentsets
2 t# E( H& u+ y) V  set roads patches with# n1 K& i8 l" g8 n
    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) or
/ \4 L" M* b3 z1 I5 c    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]: q; P  K8 ]* V4 R3 m! p
  set intersections roads with
7 r; t" ^4 `  V' h    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) and3 q/ M3 I/ b& y( g7 L$ ]! N
    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]
" m" P  H# a3 p, ~
* q+ Z7 f5 N% G6 \8 a/ v  ask roads [ set pcolor white ]
; C; D" n9 f  j" d9 f& H: x, N    setup-intersections
4 R5 b# X# K6 I2 x$ y" Xend+ h, P" L* a, ?4 Z  j6 H5 A
其中定义道路的句子,如下所示,是什么意思啊?
$ \3 k( y: r" r( {) X9 k set roads patches with0 o" H4 ]. {4 ~$ \# [9 ^% _
    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) or
! X& n% h- S; z2 s6 F9 I    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]4 z+ Y+ d% q# N  U4 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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