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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。
7 s+ I" Q5 P# T3 F+ Unetlogo自带的social science--traffic grid这一例子当中,: b) e+ q; H9 f5 n! c8 S# V
globals
) V, {7 T. r9 x0 V[
6 r7 {; n' _% h  grid-x-inc               ;; the amount of patches in between two roads in the x direction9 t/ \6 s) K( {
  grid-y-inc               ;; the amount of patches in between two roads in the y direction
" O! F3 t5 R8 F6 T* F  acceleration             ;; the constant that controls how much a car speeds up or slows down by if5 E8 H' {( S& S& a
                           ;; it is to accelerate or decelerate
+ D7 ~8 }" L# P. v  phase                    ;; keeps track of the phase
4 J9 W. r% f3 i5 {  num-cars-stopped         ;; the number of cars that are stopped during a single pass thru the go procedure3 J  O6 n" c6 m$ C0 T- H
  current-light            ;; the currently selected light
( ?$ N' [" c: L, C
+ A. k" L  n6 _0 e  ;; patch agentsets' y7 ~, c7 M8 b$ j7 R$ k( y
  intersections ;; agentset containing the patches that are intersections1 Y6 x* M8 i+ u  n6 @, X
  roads         ;; agentset containing the patches that are roads% X+ N1 l4 ?7 z
]
1 |+ X/ u" e9 G! e% R( f. f1 J( G3 _5 A; l' h- Z" Q
turtles-own0 B. |7 X' |- H! K( v1 @
[: t9 t1 _  W# y2 x  V
  speed     ;; the speed of the turtle
% f% D3 `) ^' q  up-car?   ;; true if the turtle moves downwards and false if it moves to the right: O! `3 t9 _* w
  wait-time ;; the amount of time since the last time a turtle has moved! h- ]/ [2 Z* S' G! R9 L
]
7 H+ [' Q1 d3 R3 G
2 ~/ g) i# s( ^7 f& k0 Ppatches-own7 E( U5 R+ g! l
[
# U2 f2 P% ]8 U9 Z! l  intersection?   ;; true if the patch is at the intersection of two roads
2 j5 J5 b7 m' P8 G$ i, A2 o; K  green-light-up? ;; true if the green light is above the intersection.  otherwise, false.
( J& E0 L8 C. ?! H                  ;; false for a non-intersection patches.
! M) Z' `) o5 ?9 S# l0 k) G6 L  my-row          ;; the row of the intersection counting from the upper left corner of the
% i, O/ P9 n% |$ w- C                  ;; world.  -1 for non-intersection patches.1 [) y' d$ v3 ^( r4 i6 J" |
  my-column       ;; the column of the intersection counting from the upper left corner of the
  L) a. |9 w2 w                  ;; world.  -1 for non-intersection patches.4 }" Q% u! A3 J/ H- ]' F
  my-phase        ;; the phase for the intersection.  -1 for non-intersection patches.
, m& e$ w: N& Z' ]  auto?           ;; whether or not this intersection will switch automatically.0 k- e: |2 Q8 B
                  ;; false for non-intersection patches.$ E+ ?, [" \+ |$ r7 x" W
]0 D& u1 s, W' ?, K0 Y

) {2 T' o. y" c, b1 E# t7 N. d) Y: G. B
;;;;;;;;;;;;;;;;;;;;;;7 L% S  ~; K9 D! ]. F6 z! W. x
;; Setup Procedures ;;  s& R* h6 k. a
;;;;;;;;;;;;;;;;;;;;;;% I& t4 I& D4 f. Q3 h  I
$ B' [9 ?" f) _6 O; H
;; Initialize the display by giving the global and patch variables initial values.6 j& H4 d$ @+ z
;; Create num-cars of turtles if there are enough road patches for one turtle to
( T& [, Q) Q( D$ t8 v! ];; be created per road patch. Set up the plots.! W& [6 i. Z7 m  a" @2 S  J
to setup$ p' K, k  v+ A- k4 t- D3 ^
  ca
# v' @: V/ f1 T7 e  setup-globals
/ s2 ?& J. g' q3 u" V
3 r( A; D/ E* L& `0 X5 l& B  ;; First we ask the patches to draw themselves and set up a few variables
, c5 e0 K4 D) Y  setup-patches
9 a) u7 y! i$ Q3 A. y. p0 ?  make-current one-of intersections
# W# j; [) q6 b/ o; ]6 K5 @, B  label-current2 I  G+ S  J$ T$ r+ @8 r7 H

2 |2 z2 Z! H7 K  set-default-shape turtles "car"
: N* l/ C* ~" a
! D% W; h% g- O* u) u  if (num-cars > count roads)/ ]9 m: V" V7 y+ M- X0 A- |
  [
! @9 U) O, a: u7 g    user-message (word "There are too many cars for the amount of "
% g8 P# n& W( ]( C% C1 A  f( b, c                       "road.  Either increase the amount of roads "% u  y! F" l; G5 j: d; Q( i; ^
                       "by increasing the GRID-SIZE-X or "" l7 v4 K  q3 d/ Y! U$ b
                       "GRID-SIZE-Y sliders, or decrease the "& X% z. n' E! k' ~
                       "number of cars by lowering the NUMBER slider.\n"
8 A; z+ H. z7 d                       "The setup has stopped.")
$ S% }1 Y1 f: l    stop
6 S& O% M8 z5 v4 N2 m  ]
) o( B* f# `; u  M7 P3 H( Q3 u+ |2 z5 H' Y
  ;; Now create the turtles and have each created turtle call the functions setup-cars and set-car-color% x2 v$ F2 L/ P. I
  crt num-cars+ V; I3 Q9 ?# G; f/ {  m
  [
8 N! d' V# n  z! y9 l. S    setup-cars
( T6 S1 a) ?7 W5 u: Z2 V    set-car-color6 Z% r0 H8 u0 D1 b. ?
    record-data
, ?* x, A1 @! K! u* u( B+ W, Y  ]: O8 D' b8 j4 C, F

5 Q6 o% l! q4 w# G  ;; give the turtles an initial speed
9 }  F. a- o# \. |, }4 ^# ~9 w  ask turtles [ set-car-speed ]
: i, h1 c( Q9 F& r( a$ S
( [3 a3 ]- n5 x6 p+ x  reset-ticks! _, k# H! p, L! m
end
' G" Y$ }9 q* T" r7 x* Y* G! P7 s. t0 B0 h
;; Initialize the global variables to appropriate values: I" ^% |; I1 [5 a2 f
to setup-globals8 Z& s8 H6 J0 ^" N& k
  set current-light nobody ;; just for now, since there are no lights yet
  U, d3 x0 m3 f7 r% ^- H  set phase 0  u! |1 w2 z; w' V2 K$ B, M
  set num-cars-stopped 0
. z# v. o& D( Y; ]; y) m  set grid-x-inc world-width / grid-size-x
* r* k. J1 L: D0 b7 A6 B( j, v  set grid-y-inc world-height / grid-size-y
; S- J6 C' d( K  T( ~
. Y, ^; S. v5 O$ y  ;; don't make acceleration 0.1 since we could get a rounding error and end up on a patch boundary
7 k7 d9 F2 B, M2 b$ {  A& r$ K: N  set acceleration 0.099
" i9 X4 E! o7 M2 Send
3 @6 `6 u* f5 R5 u2 V# r  @) N
+ i# h! C. x6 h  X2 Q# o& E( @! L/ o;; Make the patches have appropriate colors, set up the roads and intersections agentsets,/ n  H4 q0 S/ v+ F) S
;; and initialize the traffic lights to one setting) H( a7 K$ _1 B7 H; }
to setup-patches
' z1 J7 y( b) Y& Z  ;; initialize the patch-owned variables and color the patches to a base-color9 y6 Y! j% K/ P9 f: \
  ask patches" R6 b' T. H' ]& c5 i
  [
" p. N# L# J1 X    set intersection? false
4 p8 F6 Z" N! e, l# _! I# X  A    set auto? false
! ~2 g1 A$ f) W. k    set green-light-up? true
5 U) H5 w4 V. ^: z8 X    set my-row -1
0 L' f. U5 X3 s! O9 H    set my-column -1
8 Q8 r9 [7 @& |- I" g    set my-phase -1' j$ a3 E8 f+ A% a# ?3 s) d! i
    set pcolor brown + 3
/ r2 `) M, Y/ m. U/ B+ ^6 H2 x7 l  ]6 n; X# X  M% Y" {0 z. k0 X# N
( r3 j  J, C/ G/ A0 R# l5 h
  ;; initialize the global variables that hold patch agentsets7 B% f$ \( [7 P5 ~" G* ]
  set roads patches with
; L2 X# l7 ]) K6 }    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) or
, I  ]; b+ Z) h+ o    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]. h, G4 Q% V8 X# w4 j: M+ h
  set intersections roads with
; o8 T2 u- B* Q' q    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) and
7 i" y- _% |- ?% ~: Z    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]4 M, k- v1 U( O) `) q0 k
  D! E. f! E3 R, N0 U
  ask roads [ set pcolor white ]
* n2 h+ ?2 d, R* k    setup-intersections3 O# g! T# M0 @* R, D' b
end2 j4 v/ ?& M! \7 ^
其中定义道路的句子,如下所示,是什么意思啊?  p. v' k/ o8 B9 I. j5 R
set roads patches with
- X1 [9 _0 e! M1 V. u    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) or$ J7 W3 m  ^0 F. i' {6 v
    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]
' k) a5 u/ A9 ]' W7 C5 J4 T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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