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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。4 @, q/ E6 e4 E
netlogo自带的social science--traffic grid这一例子当中,
" C$ c' o" k1 k* N" gglobals
- _+ z. h9 m* m' X, ?, a[
7 j: Z" `& d8 Z( T7 p* h) I3 e3 R  grid-x-inc               ;; the amount of patches in between two roads in the x direction( P( D6 Y; O4 P7 ^, E$ V
  grid-y-inc               ;; the amount of patches in between two roads in the y direction
3 [  u% j, ^( K* x  acceleration             ;; the constant that controls how much a car speeds up or slows down by if% b% q; z& O0 |- `, T, V  U# ?( n7 s6 {
                           ;; it is to accelerate or decelerate, C8 r2 o9 u# t" a9 d
  phase                    ;; keeps track of the phase
8 S$ W6 z2 Q" i* p0 l  num-cars-stopped         ;; the number of cars that are stopped during a single pass thru the go procedure/ @1 z( B: g3 U" y
  current-light            ;; the currently selected light) \2 e! U7 A$ D. |
' c) b1 X+ B2 O) n- e
  ;; patch agentsets
8 ]3 {5 {: @5 Z% ^  intersections ;; agentset containing the patches that are intersections. U. l' p. e( }" ?0 N: i/ S' y
  roads         ;; agentset containing the patches that are roads9 _7 M1 j, s) b: }- O) E
]; p2 U' n+ P8 L* s8 ]

/ Z, u; d4 _# Z' C9 T7 Bturtles-own0 Q: Q5 C5 w( a8 M3 h* M0 a
[8 q) u4 t/ t) a6 Y7 @  N- x
  speed     ;; the speed of the turtle
+ L2 K+ d6 I, k6 r  up-car?   ;; true if the turtle moves downwards and false if it moves to the right
. F  E$ ?6 g& l1 y  wait-time ;; the amount of time since the last time a turtle has moved
) j! z5 N9 F# I( F# ]], t- d! M6 z0 T
8 X; _/ M* F7 Z
patches-own' r5 s" C& X" @# Q7 s  F( s9 j
[' H! x$ t& l4 T  {4 o
  intersection?   ;; true if the patch is at the intersection of two roads
( u3 K' t8 \* {) g  green-light-up? ;; true if the green light is above the intersection.  otherwise, false.
. F! S5 d6 m3 s! ~                  ;; false for a non-intersection patches.1 T& u1 j3 }$ E$ E5 B' X
  my-row          ;; the row of the intersection counting from the upper left corner of the* Z. x  A) k7 Y7 g( F- y; t
                  ;; world.  -1 for non-intersection patches.* ?" K# O- f2 R3 ^  }
  my-column       ;; the column of the intersection counting from the upper left corner of the1 X! x( h+ F' E% s1 R  E1 `
                  ;; world.  -1 for non-intersection patches.
0 L0 j8 @& z1 \" R: `& }  my-phase        ;; the phase for the intersection.  -1 for non-intersection patches.
! C% ~. t' l& |0 ?1 ^  auto?           ;; whether or not this intersection will switch automatically.
. I: B& y! _  r, g0 @                  ;; false for non-intersection patches.0 u2 Y3 g4 K8 p6 l- r; F
]
  _+ t: ^* C7 E6 n7 W
- M6 V5 Y0 c% `$ Q6 A# ]  s; ~) A4 N) ]9 E* c$ s; Q' ?
;;;;;;;;;;;;;;;;;;;;;;
+ W4 T- F+ K% ?) }; P: Z8 ~;; Setup Procedures ;;
1 K- i* p$ z2 S+ W% I/ |( S# p;;;;;;;;;;;;;;;;;;;;;;; u# n- s" O  {( G6 L9 ~8 N* T
5 n' F' \7 B, q9 X
;; Initialize the display by giving the global and patch variables initial values.  z  _6 S0 p' R
;; Create num-cars of turtles if there are enough road patches for one turtle to
& K' x! J+ k* ?( O7 @;; be created per road patch. Set up the plots.
+ H8 t, m" I% [6 h+ e+ c) i2 S9 s7 xto setup
5 c8 ~1 d# w5 f1 e( F. N. b  ca
0 c5 D! R4 ^: H! o  setup-globals
- B& T& P9 ?) F' t4 R5 W6 g( Y1 u/ m2 E8 ^7 l
  ;; First we ask the patches to draw themselves and set up a few variables6 t' U4 z. t2 _5 s: h. T
  setup-patches( z9 e) D7 g, j' h6 ]5 ~, ~8 R
  make-current one-of intersections; z$ R6 y' B  Y- z6 F6 G
  label-current
7 M! W) D; f" g4 H! f" T. l! `) d, J3 G: I
  set-default-shape turtles "car": x2 Y* n' ~3 l
, ~) _7 t. ~3 G3 u- n) k! x
  if (num-cars > count roads)
; i8 ~7 s/ @  p+ [2 B3 \, A/ J9 A  [
% s# y0 Z9 S, N6 C6 ^/ r3 {    user-message (word "There are too many cars for the amount of "
  j! B6 [, K4 X1 k. o! f" c- a                       "road.  Either increase the amount of roads ": u% I* T7 c5 }6 k
                       "by increasing the GRID-SIZE-X or "
  ?# L: {7 C6 D- |5 |* B                       "GRID-SIZE-Y sliders, or decrease the "* D0 |9 |% ~! f% s
                       "number of cars by lowering the NUMBER slider.\n"' @1 t: R: i' c2 i
                       "The setup has stopped.")/ L9 F' X) T1 Y* C
    stop
% e  t6 q+ s  |3 `2 `  ]
* x# P( m$ N1 T9 }- [3 }' b" m8 V
% i3 b/ J+ d/ K) H  ;; Now create the turtles and have each created turtle call the functions setup-cars and set-car-color
1 F& d3 ^5 G  B* h7 X! ^  crt num-cars$ c. r( |; d: k/ h' w# @/ ^
  [  i  v  ^+ z  A! ]
    setup-cars: ]  ?+ y. n- S" S* A, Y  i9 A: D
    set-car-color
) y" [4 J# w# R* K& [    record-data
$ ^! Y2 D6 j' S4 K  ]0 {' H! |' K4 y3 d1 ?4 ?& X, ]+ @

( B! y9 r, q3 D9 y- P8 ~! e  ;; give the turtles an initial speed
6 X0 X( o* {, N/ b' o) o  ask turtles [ set-car-speed ]
& R# b9 X' q8 }4 I0 g. x3 ?
' H% e; W; U' ~6 j  reset-ticks
: X9 C0 G7 B) D# [& I% Pend. ~1 z/ J/ a8 A1 g3 q3 t
% q0 B* C$ W+ }3 v2 e6 I, T
;; Initialize the global variables to appropriate values
* d/ U2 |  r% P* v8 o' ~to setup-globals
, _7 g3 b) ?' J' z+ F  set current-light nobody ;; just for now, since there are no lights yet* i; K5 f$ k- r6 K
  set phase 02 a' E. [0 v% g
  set num-cars-stopped 05 g+ ]# ]/ [6 Z2 C( g
  set grid-x-inc world-width / grid-size-x
' u& m$ D% @: J( p  set grid-y-inc world-height / grid-size-y/ I6 Q' C% J! q% O
1 c  y! f; _$ D7 u9 Z. q6 _
  ;; don't make acceleration 0.1 since we could get a rounding error and end up on a patch boundary
7 [* I- n$ {7 w$ O1 _% ~, v8 \4 K( u  set acceleration 0.0995 o, V5 H# T$ J* }/ l; T
end/ l) Q2 Q! Y7 Q1 z/ h

/ ^2 y7 E' Y7 v6 a% i;; Make the patches have appropriate colors, set up the roads and intersections agentsets,
1 ~- V, E/ B! n5 {6 J/ O;; and initialize the traffic lights to one setting6 T+ B; g/ Q" b, H
to setup-patches& |4 X# L" z/ d2 A" ?9 E. O
  ;; initialize the patch-owned variables and color the patches to a base-color
5 @' M8 M0 d, F/ L6 c) ?  ask patches
4 Q. P# z2 j1 j# @& B2 y  [" a/ L: j% W$ f) o
    set intersection? false4 U$ u; }  W$ I: l5 y
    set auto? false
' |) \; K5 R4 O- P+ N3 b3 [    set green-light-up? true
. i8 W1 c) O; ?0 [0 h    set my-row -1
. Z3 Z( v9 ]- J    set my-column -1; v6 m3 A8 Z8 i& x3 i1 d* t
    set my-phase -1
- H0 u3 K  |7 b; c5 U  B1 y4 e    set pcolor brown + 3/ A/ T4 s! T: _& E2 }5 T9 s& }
  ]2 g  |1 O+ p8 d/ Y/ Z% f9 @% u
* K2 ?4 s- I4 G+ \, h+ \4 ~
  ;; initialize the global variables that hold patch agentsets" j1 ^; R& S8 J
  set roads patches with* a, ~1 u6 _5 ?8 P  A. w
    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) or
& G7 \' m. R* Q; i" n$ s    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]) k* J2 M, D. `7 h3 r
  set intersections roads with
3 v* H7 U: V" k3 \  C0 H4 y    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) and
4 Q8 ]. d  B( X* S9 `- h) W: P    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]- `& V5 P9 f3 {7 v; d

- S" ^- k" q( q- _# G  ask roads [ set pcolor white ]
7 H# S3 a+ i5 r) H' w# D4 t    setup-intersections/ {0 [: {3 M* w0 ^: }- q1 L  o' n  r0 h, e
end
' z0 ~2 L. u4 I其中定义道路的句子,如下所示,是什么意思啊?
( J) q# {( F' S% R4 A& J+ U# e set roads patches with
! v) l% [% H2 O  V: S% D. X1 W    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) or
# j6 S1 l; @( m9 u4 D9 q" _$ \) P    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]9 m7 N% \& U, T/ M" }
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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