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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。- x+ k) [; y9 Y; _/ K2 \9 r
netlogo自带的social science--traffic grid这一例子当中,
* {4 J' s0 `9 A- {globals& |& n- ?* H8 W/ S2 u  _3 R7 S0 k
[2 i# Z: V$ D" O4 L# L; u- C- U
  grid-x-inc               ;; the amount of patches in between two roads in the x direction" ]$ R; G0 z  Y  h: e/ u$ l2 `. I
  grid-y-inc               ;; the amount of patches in between two roads in the y direction: a( a1 P, K5 b# @8 Z4 x
  acceleration             ;; the constant that controls how much a car speeds up or slows down by if
+ a) W4 N: u: H5 S. p  g" `3 N                           ;; it is to accelerate or decelerate
. P# s8 m( @/ c; c4 j( r  w" p  phase                    ;; keeps track of the phase* o/ S# P  U: V+ k# F
  num-cars-stopped         ;; the number of cars that are stopped during a single pass thru the go procedure7 F: w( Z3 r. n. L5 d  _
  current-light            ;; the currently selected light- h6 ^2 Y+ z& U" t

, v/ j" }1 R- _0 k7 h# S6 B  ;; patch agentsets( T6 m  U0 z8 y4 B# q3 R
  intersections ;; agentset containing the patches that are intersections
4 @2 L- z/ q  Y5 L  roads         ;; agentset containing the patches that are roads- @) o4 F" C, }$ A5 F, E8 [
]1 G$ N1 _, }4 x

1 }3 t  D. q3 B6 r$ }. f1 xturtles-own- g+ V6 k* M5 L- S2 L
[
, N7 G4 K3 c+ V: `! }  speed     ;; the speed of the turtle
, d4 G7 y' j6 x8 v' D, D6 t  a  up-car?   ;; true if the turtle moves downwards and false if it moves to the right
7 s5 N  z3 n1 p. n3 ]  wait-time ;; the amount of time since the last time a turtle has moved
2 f/ ?- t- ?4 \! Q' p! C]3 k) }; q3 m7 y
% D) ]6 u: [( d" O. l/ I' A, Y
patches-own
$ T, ?8 e8 m; ~* \; k9 P[
' r" {0 f1 r/ _% T  intersection?   ;; true if the patch is at the intersection of two roads4 y  [% H% X0 H+ C6 L/ N+ z8 y
  green-light-up? ;; true if the green light is above the intersection.  otherwise, false.0 H- l, k% i& d2 C
                  ;; false for a non-intersection patches.6 x, e: m" G4 h4 z9 L
  my-row          ;; the row of the intersection counting from the upper left corner of the
; @7 L+ U3 w2 J8 {1 y                  ;; world.  -1 for non-intersection patches.# h: K& `( g' D' u
  my-column       ;; the column of the intersection counting from the upper left corner of the
. c! g# ^0 a0 d7 Y                  ;; world.  -1 for non-intersection patches.
6 K; u) h! w& B4 R, S0 K/ j  my-phase        ;; the phase for the intersection.  -1 for non-intersection patches.9 B; d( s; T# {, Z  {* c
  auto?           ;; whether or not this intersection will switch automatically.8 e: K. K6 O( U$ E! u$ J* q5 q
                  ;; false for non-intersection patches.
7 W# l* D# U4 P1 u, ?$ m]* v8 _. B. S/ U+ `4 U/ Q
  N" N% E7 K! B5 t+ Z- i& b

( _$ s) m9 ]( T* B- B;;;;;;;;;;;;;;;;;;;;;;
( \7 e5 S4 V0 H, m' v& M' w;; Setup Procedures ;;
# o- x8 M( w0 M; ~6 N6 R;;;;;;;;;;;;;;;;;;;;;;$ Q% J+ g+ u- m- A$ |7 A
; z5 I% {/ z% Y4 W! v3 c1 D& I
;; Initialize the display by giving the global and patch variables initial values.
$ G+ g! I" x3 B8 \; @. v0 w;; Create num-cars of turtles if there are enough road patches for one turtle to. @9 |4 M6 [& o: k
;; be created per road patch. Set up the plots.
. U/ J) _  i$ _5 U( [. [to setup8 \& }1 J1 [  f' b
  ca% }2 M* s2 t) i, f. t! [
  setup-globals
; b  S: D7 x0 W/ I+ Q: S  e3 e8 R6 ]/ {
  ;; First we ask the patches to draw themselves and set up a few variables
. j! {7 ?5 @$ V7 M: u  setup-patches
" V8 _4 }2 ]! J( E% f8 T& _; ^: I  make-current one-of intersections5 ?2 ~5 e  s1 z  C/ y! B8 \
  label-current
) a* t: \' r) j& n# t
. m$ s/ }$ _4 i% b  E  set-default-shape turtles "car"
5 s& P, Y  w' ^9 T
3 N; ~4 L7 @0 r7 j% S  X5 S- f  if (num-cars > count roads)* \7 Y, M, p) B; \  }
  [
" Q* R9 i# v) [0 P; u, E    user-message (word "There are too many cars for the amount of "/ D9 L. I: _( \" k3 ^( H( _
                       "road.  Either increase the amount of roads "/ ^2 S5 a4 M( N7 n
                       "by increasing the GRID-SIZE-X or "" b5 q0 b9 d2 G# P* r7 W
                       "GRID-SIZE-Y sliders, or decrease the "
. q( ^2 u+ C- ]                       "number of cars by lowering the NUMBER slider.\n"- H) s/ }9 B! E  S1 m# X2 X
                       "The setup has stopped.")
# @/ Z7 Y+ b0 }0 v    stop  r, g7 k& D; ^7 S, L/ @
  ]0 K* j4 A4 }/ G* w, j5 @  M# W" X2 k
' u; c5 \2 t& W
  ;; Now create the turtles and have each created turtle call the functions setup-cars and set-car-color
" i+ [2 E; c- b  crt num-cars
2 x( q+ l4 s3 g# G  [
) X( r8 c# K3 e% l    setup-cars
; g1 d% N6 ?- ~! ~. n4 G9 Y7 V    set-car-color, k* D' H1 t1 s, c8 _" i
    record-data
' {/ A2 f- R7 `( ^, Q6 P, O0 S  ]6 U% N. |  E4 N2 w
( Y# P3 g4 S3 S% ~$ i
  ;; give the turtles an initial speed
' W3 k& ~1 e$ t0 p( |  V1 B  ask turtles [ set-car-speed ]" b* [' c- H( w+ M

7 r$ f$ p/ P+ j* @, p, S3 C" X  reset-ticks
; s2 o* ~  M4 ^end1 R( n+ H. t. E. B& E5 U

8 O+ }* D$ v2 M6 C6 i;; Initialize the global variables to appropriate values
/ j1 h( @  Q/ r/ d" C2 uto setup-globals
- X& s2 H8 v$ |/ k6 L4 m) E' s! {  set current-light nobody ;; just for now, since there are no lights yet
. C# n7 N$ G  d  set phase 0( o8 D: K1 q; k5 S8 }2 W% w
  set num-cars-stopped 05 g3 G! F8 x1 m9 J+ b) N
  set grid-x-inc world-width / grid-size-x: l$ D" B  \$ n
  set grid-y-inc world-height / grid-size-y; B( n; H4 c+ N( X) b8 O/ \
9 I" I+ _0 t( N! X2 d# `
  ;; don't make acceleration 0.1 since we could get a rounding error and end up on a patch boundary
4 T& M  F$ `/ n6 l  set acceleration 0.099! x" Z) H* H! U8 N- U9 ^. m, i
end. }( v0 F9 \2 a5 J/ j

9 O3 |7 R" r* R" };; Make the patches have appropriate colors, set up the roads and intersections agentsets,* Z+ E9 X5 P. \; c6 }, w: C
;; and initialize the traffic lights to one setting4 `( g. f" p" U  |  _+ o/ K& ^
to setup-patches
1 ?' _( L4 m9 w, C7 F9 U5 {; {  ;; initialize the patch-owned variables and color the patches to a base-color
8 k4 f0 K& y+ \$ w. z  r4 I  ask patches
( G8 [4 \3 v5 {  K' Y0 |6 x1 }6 R  [4 ~; o* ?" v; k/ x; d, r0 x; d
    set intersection? false
' g( C- B% k0 _! `3 O: C    set auto? false: X# h) N0 L' C& M! n, b1 A1 M' E
    set green-light-up? true4 n+ c2 e8 c1 F6 ]# Z* ?
    set my-row -16 A/ o7 ~" `/ T& z9 [# ~
    set my-column -1/ T+ D; q# [' h9 L
    set my-phase -1
  {# I9 s; X$ W; X( M    set pcolor brown + 3( K+ _5 l; _' h
  ]! c0 `3 d. T/ W3 e8 Q

- O2 I8 [8 i. ^, r) q  ;; initialize the global variables that hold patch agentsets
& ~- Q% V$ B/ F9 \: S* \! Y/ H  set roads patches with/ h( E1 K& _, c+ s# K' p) R: _
    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) or
3 c& f! z+ V$ H4 F% S( T1 f5 y    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]# _- t! f& L% ?
  set intersections roads with# ^3 P4 K: ^# g* Z. p+ Y
    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) and
( d* z: t5 K' M7 g0 s4 E3 N5 a4 L' P    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]; A7 X& G1 w9 v) \7 O# Q

, e$ X2 V$ r3 H8 P+ T  V% ^! ^  ask roads [ set pcolor white ]
. y) z& W$ q+ m1 _. s    setup-intersections
' c& I  ]* P9 T2 qend
" a4 [' f* ^  R6 {0 S: v4 M其中定义道路的句子,如下所示,是什么意思啊?
: C: I& f, g- Z/ D' n set roads patches with
5 K- @, v. K5 p7 f% @    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) or
" `( M5 O% \" y$ d) u& x) a: a% Z    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]
# O) g5 o, A/ E$ p' z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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