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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。' v8 z  |* e6 m7 ?- P9 j
netlogo自带的social science--traffic grid这一例子当中,
. g# K3 {% n$ Mglobals$ c) U9 P; M7 V6 k
[' {4 D5 `/ U5 |4 O. k- R2 B! H) d+ n
  grid-x-inc               ;; the amount of patches in between two roads in the x direction
: z5 C0 G9 B* W8 Q! y+ W2 U+ b7 z  grid-y-inc               ;; the amount of patches in between two roads in the y direction$ Q! p+ b/ ^* M# S* t  w/ E
  acceleration             ;; the constant that controls how much a car speeds up or slows down by if3 c6 X" K9 l$ G9 o' ~
                           ;; it is to accelerate or decelerate  \& b/ C( U+ ^+ h* E6 J
  phase                    ;; keeps track of the phase1 D+ _' `& M# V" x$ |0 b
  num-cars-stopped         ;; the number of cars that are stopped during a single pass thru the go procedure
7 m$ r& L8 \- ~  current-light            ;; the currently selected light
. g% C) N  I  ]/ m3 ^0 F  Q% D" I3 T8 D6 D' m% h) g
  ;; patch agentsets
/ h* ^! K0 s3 b  intersections ;; agentset containing the patches that are intersections5 C/ E9 X! w% O2 E' P/ |! q  c& F+ r
  roads         ;; agentset containing the patches that are roads
& [5 B% _/ Q$ H6 []
* F& G8 A  [, t+ h% g8 J3 N) h
* f3 z3 _6 T' I5 c( i8 Pturtles-own0 Y4 B3 J! I1 T4 a$ j
[/ P. N+ ]2 b% v; h# T7 W
  speed     ;; the speed of the turtle
5 s9 `$ `$ b% A' N5 i  up-car?   ;; true if the turtle moves downwards and false if it moves to the right
! d& a. d' Z/ j% X# Z- `  C  wait-time ;; the amount of time since the last time a turtle has moved
+ F1 ?. P" v& ^5 W% s# A1 ~: N]( c9 r. [, @9 R; i  U/ G# n$ X

, D  H6 f2 ?7 _6 {4 ~+ @patches-own
2 M. v) R5 {* _8 Y[
. T0 n5 [' A4 O' i# r: W; k  intersection?   ;; true if the patch is at the intersection of two roads
! D" O- i; m$ @  q  green-light-up? ;; true if the green light is above the intersection.  otherwise, false.
  B( J+ M7 c/ c% G                  ;; false for a non-intersection patches.
* B% f' k8 x6 w" Y  my-row          ;; the row of the intersection counting from the upper left corner of the
9 r6 {. a5 x  Z  N9 x                  ;; world.  -1 for non-intersection patches.) f, I1 B) O% R; s
  my-column       ;; the column of the intersection counting from the upper left corner of the7 D6 b3 [% e7 \, m5 P1 @
                  ;; world.  -1 for non-intersection patches.
, y, T6 S7 U: ^! w4 l  my-phase        ;; the phase for the intersection.  -1 for non-intersection patches.! a* U7 j% o; l) ~" ~0 ~
  auto?           ;; whether or not this intersection will switch automatically.
  U/ C/ e* A7 S9 n; i0 \6 ~; V                  ;; false for non-intersection patches.  X% m' w4 z% {# a7 H$ ]5 t9 |
]% N4 W0 d- g* [) G

& ~' T5 X( X3 M. c
: @" B( {: @2 c- ?. b7 P. Y;;;;;;;;;;;;;;;;;;;;;;, L4 z- N# P8 q3 M6 Y7 z4 q' G  l
;; Setup Procedures ;;
; r/ I8 Q6 a- |) z;;;;;;;;;;;;;;;;;;;;;;
; L5 ?4 P0 I4 b' U# g0 {8 t  B9 J6 y& j* ~% J; l
;; Initialize the display by giving the global and patch variables initial values.3 @9 E1 n/ O% l  q9 ^# w( `$ |
;; Create num-cars of turtles if there are enough road patches for one turtle to$ ^& s7 @/ S9 z  _2 ^7 {$ M; f2 b
;; be created per road patch. Set up the plots.
" v: ?) {; B9 E. o  R5 `! f: U8 sto setup
4 I. }! W8 z0 p7 k7 o% p; f5 J2 _  ca
& b) H  \% y  v0 g  setup-globals
; ?. j; {5 w2 ~+ O+ x* g4 P/ Q" m2 m" i  ^" e3 w# f
  ;; First we ask the patches to draw themselves and set up a few variables
3 j  C. E: L9 ?8 L  setup-patches9 F: m6 G& n% K; t' Z. n- G
  make-current one-of intersections. O7 _* A! h* m
  label-current
6 o5 F2 X9 I5 X) F3 D0 q
6 v0 X. E$ r/ j/ b9 }+ I% K+ h  set-default-shape turtles "car"0 y, m! X2 v5 ]7 @$ s
* A" a: d, Z9 c5 i- b% ]; ?
  if (num-cars > count roads), B. S( [; f7 C" A4 O7 ^
  [
* _3 H$ T. w. I    user-message (word "There are too many cars for the amount of "! J/ K1 d# [7 a7 C% ~% \( H
                       "road.  Either increase the amount of roads "  |% K3 i1 E- j( ^/ ?
                       "by increasing the GRID-SIZE-X or "
1 S+ _3 g1 |2 e' K$ c' ~                       "GRID-SIZE-Y sliders, or decrease the "
/ E* u: c( E5 L" Q                       "number of cars by lowering the NUMBER slider.\n"
" h/ z; w. n, r9 g8 S  ?, G7 ]7 r                       "The setup has stopped.")
* n; z# k: k0 D5 n$ u! O& z/ a    stop
4 L7 V6 L7 |6 {  ]
+ e) q+ N9 ], D) ~! \: m  o% Z, M% v# R3 @; X' R
  ;; Now create the turtles and have each created turtle call the functions setup-cars and set-car-color
1 h! q7 M. T, K$ V5 {  crt num-cars
  `. O5 q% l- ?: X4 q6 A  W  [4 T! O( u$ I8 m. f# u
    setup-cars* r: T* o+ v# _" x4 e
    set-car-color
, [6 W; }) {4 r2 w: {) e    record-data7 A' q3 Z# d! p8 F
  ]
1 @' _; Z3 R, o5 W, {
4 s) a5 N" G$ U- l  ;; give the turtles an initial speed
: j7 Z- N- e1 X2 S) O% d4 }. O7 J  ask turtles [ set-car-speed ]
1 p5 a& L7 ~6 l1 ^, G8 H7 c7 A9 x5 @
  reset-ticks
8 r1 ^- N2 H( E7 z% F0 E+ E, `end
: _# Q* T4 z/ N5 [1 Y& R
! g: j% e; z: A' |/ {+ L. w7 E* y6 @;; Initialize the global variables to appropriate values' u' Z% V6 b3 \6 |# t7 K
to setup-globals
% z1 O2 Q0 \' H  set current-light nobody ;; just for now, since there are no lights yet
* v3 ]1 a5 @! E  set phase 0' U( `$ ?, `- G, t' G) M& |
  set num-cars-stopped 0  E: ?3 ?9 x9 V* |
  set grid-x-inc world-width / grid-size-x! m+ V  p# Y# `  G- I* Q
  set grid-y-inc world-height / grid-size-y6 l1 X+ K3 i- ?. t2 a$ n

! M5 P1 ]. F2 y# ~7 M& S! M  ;; don't make acceleration 0.1 since we could get a rounding error and end up on a patch boundary, B3 e( Q) F; ]7 U& f/ E( j& h* ?
  set acceleration 0.099
" \  g' v' X7 wend
- r% t% y& N) b' v7 c5 Z* X2 b! Z# I' B+ r6 B
;; Make the patches have appropriate colors, set up the roads and intersections agentsets,
, i8 h* \- N, x9 e) q4 X% f;; and initialize the traffic lights to one setting
  i7 p3 @0 J. g/ w+ X9 z' [to setup-patches
0 F! c4 U. A: K* G" Y  ;; initialize the patch-owned variables and color the patches to a base-color
6 R' d: y* o5 q5 @  ask patches# V' B1 r0 O6 E# I
  [
1 Y5 a' Q3 d2 d  E2 i$ l8 j    set intersection? false
) e1 J- {2 L& d) b    set auto? false/ D9 f" U, ~+ H% Z( |
    set green-light-up? true. z/ Z8 |% q6 y
    set my-row -1
4 K* j% f7 u7 }% O    set my-column -1
& z7 i- V3 O% ^4 G0 Z( R0 d- m    set my-phase -1* g, j# t/ Y2 N3 a! y
    set pcolor brown + 3* ?: [% g5 M/ B+ \1 V: b8 f
  ]
2 ]( U. b- Z! S5 l  f: T/ z
1 D3 J+ s# s+ |* Q  {' D4 ?  ;; initialize the global variables that hold patch agentsets3 X! b/ V: a1 \& F9 r" v  q  a6 T
  set roads patches with1 a# V% s8 }3 S
    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) or
8 N- e( [1 H) D% h. }    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]
; U6 p% _9 i  F1 ?5 e  set intersections roads with6 ^" q$ r; \& k. ]) Q6 O
    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) and0 ~  @9 j6 N( _; j  _
    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]
. e( `8 z/ O$ M* r  c& b+ b9 J( |, E5 ]2 R! l2 \. a
  ask roads [ set pcolor white ]
; p* G6 e" b$ R0 s  z+ @: j. `    setup-intersections0 u$ ~2 I* k/ H, O! A" q1 M0 X
end
8 J: Q" Y9 ]) x' I! O其中定义道路的句子,如下所示,是什么意思啊?2 V0 l& N6 @  r. N. I9 Y
set roads patches with7 j# L4 \$ l: ?. X
    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) or/ Q# Y) ]1 D* F: t) o
    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]
# Z" _' s  X1 X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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