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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。6 G6 G5 q+ D" F' M6 \5 }7 ]: C5 ^
netlogo自带的social science--traffic grid这一例子当中,8 [7 |# T% q4 K" T" k( C' s
globals
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  grid-x-inc               ;; the amount of patches in between two roads in the x direction( v" Q, f3 g: w3 c7 |
  grid-y-inc               ;; the amount of patches in between two roads in the y direction
: y. M4 f7 ^5 J$ P  acceleration             ;; the constant that controls how much a car speeds up or slows down by if- R) w' k& _2 k0 \" q6 Z
                           ;; it is to accelerate or decelerate7 @6 b2 m4 t, r, v& j% z
  phase                    ;; keeps track of the phase
* U, K( E4 y9 V; ?4 z  num-cars-stopped         ;; the number of cars that are stopped during a single pass thru the go procedure
2 V  K; d0 I4 j9 ~( I& b# Y' H( c  current-light            ;; the currently selected light: s5 q" z. l3 b0 t! f3 `
: K/ E* m: B7 _6 s( n9 W7 M
  ;; patch agentsets9 v! K+ P+ ]! b3 L% X% p" ]
  intersections ;; agentset containing the patches that are intersections# u* v/ A, T8 w
  roads         ;; agentset containing the patches that are roads
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turtles-own
" g( n  }/ ~1 `$ L  T8 |[& h# g1 j4 C! e0 L5 J0 x4 S0 j
  speed     ;; the speed of the turtle
+ t- J' V0 b2 C  up-car?   ;; true if the turtle moves downwards and false if it moves to the right6 y7 ^  L8 V: h: a' v2 \. I
  wait-time ;; the amount of time since the last time a turtle has moved
! C' D& G$ y, w9 N# q; z]
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patches-own
5 F' Q! a# J4 \6 g" F, F! }1 x  n[
2 ^& R3 y/ F) |, f  intersection?   ;; true if the patch is at the intersection of two roads
$ h" |9 m" h: ^6 l' F& ]  green-light-up? ;; true if the green light is above the intersection.  otherwise, false.
8 b! n5 t7 c) D1 Q* e0 X" t1 E                  ;; false for a non-intersection patches.1 R. T) c- d1 `2 d0 Q3 ^
  my-row          ;; the row of the intersection counting from the upper left corner of the! k+ j8 Z$ d9 S7 _+ E  N8 }4 h" i
                  ;; world.  -1 for non-intersection patches.
5 g. Y0 \9 D8 H8 w, r+ j/ ^  my-column       ;; the column of the intersection counting from the upper left corner of the, k$ ^$ O/ g4 b2 @' o( F3 y. `; R
                  ;; world.  -1 for non-intersection patches.) @, q- T* n0 V
  my-phase        ;; the phase for the intersection.  -1 for non-intersection patches.6 A: d9 O- J3 G- K" @- |
  auto?           ;; whether or not this intersection will switch automatically.3 n0 S/ q" I3 W
                  ;; false for non-intersection patches.
  M0 l: I- V! Q& o5 u0 r) q0 `& H+ u]( p0 s* |  e4 u7 M

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+ v) y+ x& i* e6 s/ {! O% h;;;;;;;;;;;;;;;;;;;;;;2 N" G- {* n& S6 N( F0 [4 X4 U! ?/ O
;; Setup Procedures ;;
7 D$ J. U! b' L  c2 Z  S+ m2 A;;;;;;;;;;;;;;;;;;;;;;
4 T0 X$ [& J! W( s  A+ G! o; P+ K1 w: }+ E
;; Initialize the display by giving the global and patch variables initial values.
% H+ f6 z4 s5 y" @+ A;; Create num-cars of turtles if there are enough road patches for one turtle to
7 }% S2 w2 L  ?  W$ @, c;; be created per road patch. Set up the plots.- S" ]4 F  a/ L5 h: S
to setup
4 g7 H* y! ]  y  ca
& R: s# [; I: O: Z* ?  setup-globals
3 J- N' n- d2 _& i
2 q  C. S: c3 t3 c  ;; First we ask the patches to draw themselves and set up a few variables
( V" `; |4 V7 t" N' C, f" O  setup-patches5 T; c" |1 [: g2 @. i9 }* _6 a
  make-current one-of intersections$ d/ y, [* f! f' C5 i/ q4 E
  label-current. Y- w  p& y( g2 v; `- ?

8 f  j2 S0 ]) Z+ f1 E/ S7 r  set-default-shape turtles "car"
! r6 g: {2 D- W3 j4 s6 N/ N+ J# L2 [* \- A- M7 E5 e
  if (num-cars > count roads)
( s. ]2 g) H0 }5 z" D+ {* J$ }  [. M. r4 I/ J1 K4 ]- q0 l
    user-message (word "There are too many cars for the amount of "$ }) g6 K. T. C( ^
                       "road.  Either increase the amount of roads "% O6 g" x# ^9 R0 D: @
                       "by increasing the GRID-SIZE-X or "/ Y9 R# _; K- ?2 E  e. j
                       "GRID-SIZE-Y sliders, or decrease the "" r: }# J& [7 [" d
                       "number of cars by lowering the NUMBER slider.\n"0 T1 h  Y" r2 J0 |: J; V6 v
                       "The setup has stopped.")( t0 j6 D/ W' i
    stop
; e5 e4 q2 J+ \0 T7 s. R2 u7 b  ]
4 a  z3 ]- K3 d, s" Z) J3 t" Z
: T% [/ H9 Q" \6 h  ;; Now create the turtles and have each created turtle call the functions setup-cars and set-car-color
  Y, _# u" D+ k; u& v2 I  crt num-cars
7 V% z6 j$ J. i$ r7 c. q  [; |2 e# G% [) A7 m( c
    setup-cars
! Y% v- m) ^% m& _1 u3 W9 g  x; s    set-car-color
! J% J& c, v* S' u' w- \    record-data: c9 s- D9 b( _- H, S; L  d
  ]
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8 l9 w* W' {0 \3 t) y, t  ;; give the turtles an initial speed
* t/ [" d0 x$ e+ C  q- q  ask turtles [ set-car-speed ]9 e) a, p/ [  O3 q! g$ o8 {1 ~/ M
' N. q; V3 n1 P/ q7 r
  reset-ticks
3 v% e! ^* C/ `* q  _. lend  F/ x  M% o) a/ P$ }

; }# P& X" R" Y% e4 d! D# ~;; Initialize the global variables to appropriate values
5 B( n7 G3 u" w2 cto setup-globals5 ~, Q4 c' x1 j( H; h0 j6 ~8 r- A
  set current-light nobody ;; just for now, since there are no lights yet% P. h9 F, @: D0 A
  set phase 00 Z1 s, d! H! T: Q
  set num-cars-stopped 0
  d7 `3 K1 ]& c6 w2 S0 S1 {  set grid-x-inc world-width / grid-size-x
* B/ J& q# K- [- H8 G# q  set grid-y-inc world-height / grid-size-y" m% ^: ]# A; C* I( N1 ~7 W; |+ U
  T5 ^. |: G$ S9 D) D0 |" j  b! I
  ;; don't make acceleration 0.1 since we could get a rounding error and end up on a patch boundary
$ ?: Q3 y7 {; J8 b8 C$ M! M: v5 Y  set acceleration 0.099
' N$ ]9 H+ `% d! P, ^! a& u% Xend
7 o0 v( J2 U' k) D1 a+ _+ a8 \
. s2 F5 B6 b2 c3 M  y;; Make the patches have appropriate colors, set up the roads and intersections agentsets,
. i4 [. }: Z; Q;; and initialize the traffic lights to one setting/ B. Y; X. g4 A% X6 r
to setup-patches3 |3 L) g! E+ e9 G1 L5 u; u) S" G
  ;; initialize the patch-owned variables and color the patches to a base-color5 b4 @7 @8 {/ M
  ask patches  H5 |7 D* O# F
  [
4 a$ p" W+ x/ n1 T  L* a2 K. B3 n    set intersection? false
4 c. a+ T- [9 O! K7 B  I+ T    set auto? false" B6 B& ^6 N; J+ e: R6 ?4 J
    set green-light-up? true! }/ [2 ]4 z! K! D. j$ i7 Z
    set my-row -1
) k9 `! @/ H$ ^4 B" v    set my-column -1( w! y  ^1 [' [7 ~5 e( R9 W: A; [8 o
    set my-phase -1
6 e: m7 L' K0 l) O; n# o4 O5 q    set pcolor brown + 30 E  o* j# x4 x. v9 H% q0 v# d" ?  y
  ]
. t# n* e- U7 \7 t' Q" C4 v" O: S  L- g7 f7 K- }9 h0 Z4 _" V
  ;; initialize the global variables that hold patch agentsets
7 s( W) N& ]7 t( R1 p; V, ]  set roads patches with
& b4 }: [4 U0 |  t    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) or/ V# A* _/ }2 d
    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]
7 G8 G. n- R4 @9 X' \% g  o  set intersections roads with8 v" {- E+ l0 ?3 e+ R6 H: h
    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) and& R4 ^3 S9 e! d( b# i: O  f' {
    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]
" x% q; k" x, ^/ Z" p0 Y) o; O0 c" L1 l' D
  ask roads [ set pcolor white ]% N7 y3 a- ~1 d$ q- Q$ |
    setup-intersections% k2 i9 v. Q! l, c$ b
end9 V+ D: A/ d8 |: R9 q# m
其中定义道路的句子,如下所示,是什么意思啊?
2 G+ B. |4 q- n+ J set roads patches with
1 N( z9 R: I  v* N: \    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) or
$ E: ~1 w+ p5 u# v$ p# ]6 i8 N0 X8 @    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]
4 l( n; T0 B# O: d% q: f: W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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