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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 N! e% z% d5 l  e  Z* W$ c
netlogo自带的social science--traffic grid这一例子当中,8 o, h4 i; V3 R4 w* A
globals
5 U2 |5 K; W* F/ H( O# i7 [[9 ]$ o- p# |' H
  grid-x-inc               ;; the amount of patches in between two roads in the x direction1 h- {# B, b5 _+ z# ?( m, o
  grid-y-inc               ;; the amount of patches in between two roads in the y direction0 t4 P. t' q8 h' w: }" Z
  acceleration             ;; the constant that controls how much a car speeds up or slows down by if' }  d$ a$ |2 m
                           ;; it is to accelerate or decelerate) K7 l2 z) x3 N# v$ M; \8 ?7 C4 _
  phase                    ;; keeps track of the phase" \" q  ^6 b9 D, H
  num-cars-stopped         ;; the number of cars that are stopped during a single pass thru the go procedure
' r  ?  i" b4 p  X9 D. ]5 a! T  current-light            ;; the currently selected light1 A+ h4 b" }# Z) }) ^. s) o
, D  S9 p, d, i7 }# ?8 j
  ;; patch agentsets1 Q$ r7 X, @- T3 G9 g
  intersections ;; agentset containing the patches that are intersections9 h. k* a, e- m4 t
  roads         ;; agentset containing the patches that are roads
6 E: N: k- _! U! J, d# d# v, @]! z* I( o+ c! m# s
+ C8 P) M7 N, @) e2 U
turtles-own9 Z( M. @* [9 ?, @3 s0 k4 q7 Y. W
[
% R0 r* M. x. _9 f& [8 _5 S  speed     ;; the speed of the turtle
8 |4 I( r, |. p/ b3 Y9 ?% H  up-car?   ;; true if the turtle moves downwards and false if it moves to the right
  ^* A# `2 G/ W  o1 s  wait-time ;; the amount of time since the last time a turtle has moved
( p$ `! f* N2 x$ t1 w- T]! X# `! J8 p; I) r  k  H: Q$ }1 H" f5 s
2 ~6 M0 V* g4 w# e6 p8 @" ?
patches-own/ h* f3 k8 Q9 k3 A2 E
[
. a, k( J8 h5 Z/ T- x( g/ Q  intersection?   ;; true if the patch is at the intersection of two roads
3 ^# e7 g0 I  |9 g  C1 G  green-light-up? ;; true if the green light is above the intersection.  otherwise, false.' c$ W7 z* q* \* Q1 l
                  ;; false for a non-intersection patches.
, K7 r' @5 \2 C* e1 y  my-row          ;; the row of the intersection counting from the upper left corner of the
" G& k' t2 b. X* @" F" U4 [1 |                  ;; world.  -1 for non-intersection patches.! V# T# M5 L+ H% l( N- X5 @
  my-column       ;; the column of the intersection counting from the upper left corner of the! h4 \! o- Q/ i; o
                  ;; world.  -1 for non-intersection patches.
$ W5 I2 R5 L% ^" V6 _* p0 P  my-phase        ;; the phase for the intersection.  -1 for non-intersection patches.
) D1 n$ ^: u; k/ a, V2 D8 V/ ~2 n  auto?           ;; whether or not this intersection will switch automatically.
6 H1 C  s7 z% }- ]. t* J; P7 ~                  ;; false for non-intersection patches.
( v9 ^% i6 ]8 {3 Q: t1 F" {) ^. y]
. J; D! E8 ^( R& K; Y4 e* j- x
" k3 [8 x" Z- ?' ]; n' |9 R
8 e' |3 v" }* ^5 ]% m1 y  K;;;;;;;;;;;;;;;;;;;;;;  E7 }( b# U, i2 `( u7 m2 ~
;; Setup Procedures ;;( M$ K3 E  c- D5 j/ ?& q/ A
;;;;;;;;;;;;;;;;;;;;;;
4 {7 [6 P' b& s' k0 P) [, e+ l  C7 W! y1 I, j% L
;; Initialize the display by giving the global and patch variables initial values.
" Z, ?# g7 ^; f5 g;; Create num-cars of turtles if there are enough road patches for one turtle to
" O9 d% @  o7 {" K2 U' a. |;; be created per road patch. Set up the plots.
4 y9 R( S! K3 J6 `( g. mto setup
- w, l3 A1 f( w+ d' L% p; j  ca: t. j. {2 Z( N  q" r/ Z# q3 k1 R( x
  setup-globals
' F9 t  q$ f; l' ]5 e$ b( Z2 D) y# S, x1 }& ^+ S2 |
  ;; First we ask the patches to draw themselves and set up a few variables
. t+ p7 G: [, W7 t+ y3 w  setup-patches3 `( |& t; r$ S; z
  make-current one-of intersections
" I3 W, L! ]( ^7 C  k9 m  label-current( X3 A; G+ Y% |( K9 B( ?6 _

4 K, f& o8 h0 b/ j: ]$ O  set-default-shape turtles "car"0 S* T0 S! v9 o6 A( Q8 b
, y- F1 U" X8 o- \5 t/ e
  if (num-cars > count roads)
: y, \; ]0 Y) W2 }  [# J3 d0 Z. r' a3 N' z) M* w" O5 n
    user-message (word "There are too many cars for the amount of "
2 @+ ~. X( a, F0 A- Y                       "road.  Either increase the amount of roads "
8 H8 N7 `7 R4 |# d+ R* H1 K  K                       "by increasing the GRID-SIZE-X or "
% Q: }9 R& J# i7 P# ]! E! l% n                       "GRID-SIZE-Y sliders, or decrease the "
' m" M# v. d! k0 S+ b                       "number of cars by lowering the NUMBER slider.\n"7 H) K9 v& F3 X5 V! B$ s# E
                       "The setup has stopped."). K- i3 u/ `# `% ^, f  ?
    stop! R3 ?- N% V0 W9 F" `
  ]7 s$ v% }6 U5 j& A: |5 D* X' L1 V
1 q7 H+ X1 T! u! D/ @4 k
  ;; Now create the turtles and have each created turtle call the functions setup-cars and set-car-color
$ o* r& w! S8 \5 x$ l  crt num-cars) o9 ^0 s# d0 V% Y, j$ F) M) W2 N- x
  [
. k  v# X7 N% |% _+ i6 ~    setup-cars
  ~( g, I& h& X2 K1 y    set-car-color
5 w9 w4 I  O# A6 f    record-data5 l) b' g2 m3 ~2 U" M: I- r" a
  ]8 F8 h& Q% U7 _. r0 C7 i; c1 y
& J4 y2 n: q6 q- W8 i
  ;; give the turtles an initial speed3 K! n" `4 z* X8 i$ [2 \7 D9 Z
  ask turtles [ set-car-speed ]& o& _. ^7 d; [) y% `( Z9 x
7 _8 W* J  Y/ z$ Z: r
  reset-ticks
5 \3 k& ]# A) mend1 j. d2 E9 s( M; R
' [+ n. X) c4 i* G+ U: h
;; Initialize the global variables to appropriate values' `7 I* {5 u' J
to setup-globals0 K% F3 u% O/ `: v, p8 v) a# w
  set current-light nobody ;; just for now, since there are no lights yet" I1 m1 a  R6 {& I. X1 F7 X
  set phase 0$ ]6 n0 h& S6 _& @/ D  G3 w
  set num-cars-stopped 04 ~5 p5 B( e# q! L1 `+ X
  set grid-x-inc world-width / grid-size-x+ Q- B6 a1 N+ j! \* p6 |; R
  set grid-y-inc world-height / grid-size-y
1 q6 m7 O) V' z$ U" ?
$ Z$ B$ K0 O/ q* w0 ~8 P  ;; don't make acceleration 0.1 since we could get a rounding error and end up on a patch boundary
0 N' Y$ {8 [6 n+ ~! Y  set acceleration 0.099- _- J- c# v9 \; Y( _, K7 N
end+ G$ L+ N2 i. h
. e8 d( {, w( Y* I( J/ U7 C
;; Make the patches have appropriate colors, set up the roads and intersections agentsets,/ u" `8 `$ E5 I0 B3 C8 H0 h4 Y
;; and initialize the traffic lights to one setting1 ~! r2 X( Q" D9 p9 m7 h. v3 G% |
to setup-patches
; r' h$ H, {* N* Z  ;; initialize the patch-owned variables and color the patches to a base-color: `# I5 u4 l" z3 ?4 b
  ask patches
- c3 X$ X. h* F% x- V0 d* I  [& ]' Z" X$ K2 c  }; x9 [/ Q
    set intersection? false
* c4 \, }9 M6 W, f) x( M    set auto? false
3 W; e$ N' r$ X$ S2 B3 U0 B    set green-light-up? true, |/ }0 t# y$ k
    set my-row -1
- t6 l0 W! }  N4 i& \    set my-column -1
- |6 m% }0 S9 S1 T: T$ x    set my-phase -1
# i( r: b. E% @4 z    set pcolor brown + 3
& L7 j# P1 H: u" Y  ]8 ]+ P; v3 Z. b- s

5 f# x$ M* `1 N( z: [7 t* q8 O  ;; initialize the global variables that hold patch agentsets
" o; C; d0 y2 ^) B( R2 O9 [  set roads patches with: q  T1 [* r* \' P: [) T
    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) or. a- L. K% g0 l- _# S) A
    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]; w! n+ X4 z% E% @% N4 z
  set intersections roads with
0 M' e$ e: `. o0 u- H    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) and! E; U" D) V. u. Y
    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]& i. T. I6 u% h! d  @3 I

- H2 m% K' E. U: H$ X  ask roads [ set pcolor white ]
2 Y& s; C* j3 E: _8 S6 e: Y    setup-intersections& S* I* B- K4 r
end
" P7 ?7 W; F9 E# n% o其中定义道路的句子,如下所示,是什么意思啊?
1 ]- o/ n9 ^8 `. K2 C set roads patches with
9 {) P! t7 w" S6 l! z# H    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) or0 V; N$ a! E" L5 S) {# H
    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]
3 g5 {' F) B  P+ w3 k. C0 p) 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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