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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。
: J; J- F0 V6 z7 fnetlogo自带的social science--traffic grid这一例子当中,
/ E$ J' h4 J% p) Oglobals
' t3 d2 ~" `" ]- \2 @( l0 N[
; v- U: `+ ^& j* C+ S. Q  grid-x-inc               ;; the amount of patches in between two roads in the x direction# S" f( z4 \& A, s% @
  grid-y-inc               ;; the amount of patches in between two roads in the y direction) S: N; i' p" H4 m$ t- _# P
  acceleration             ;; the constant that controls how much a car speeds up or slows down by if+ ]8 h) _  B6 D0 v0 n: [9 Z" E
                           ;; it is to accelerate or decelerate
  c/ F9 Z4 J1 V% v- L  phase                    ;; keeps track of the phase& W/ {/ [* M. z* p. W
  num-cars-stopped         ;; the number of cars that are stopped during a single pass thru the go procedure
+ B- l" }" S' P! g3 v, ~6 m  current-light            ;; the currently selected light
+ o% c4 Z2 H' w7 D  i4 d9 R( ^2 h. C, y$ o- o4 Y+ i9 ^
  ;; patch agentsets
+ I: C$ A3 i9 X/ ]6 S# B  intersections ;; agentset containing the patches that are intersections7 C, v4 a, V* y8 r! o
  roads         ;; agentset containing the patches that are roads
) {+ c3 m6 T* S3 L, v4 x  k]# K# d4 b2 j+ T& d; w1 T
* f$ h( S) n, n
turtles-own
) A) j' f- N: q  h[3 j1 V$ A1 Z) {
  speed     ;; the speed of the turtle9 o$ q$ S" h$ O2 Y) a
  up-car?   ;; true if the turtle moves downwards and false if it moves to the right
5 i8 ]: h2 B5 H  wait-time ;; the amount of time since the last time a turtle has moved
2 F7 U6 B9 V3 ~* p4 D1 m* u6 r]
* a  |" B: n& P3 k* [
8 W1 g( r* z5 I; cpatches-own$ }) G# Y+ K' D: x
[
# P) U5 c9 f. [7 ~. i! \  intersection?   ;; true if the patch is at the intersection of two roads
+ ?/ ^) n# J" h0 B$ F  green-light-up? ;; true if the green light is above the intersection.  otherwise, false.
5 i2 [/ M) z* h$ i4 }9 P2 o                  ;; false for a non-intersection patches.! _1 b& R! Z/ U$ P$ r
  my-row          ;; the row of the intersection counting from the upper left corner of the
. n+ F6 E9 M' s" ^, b8 f( I* g                  ;; world.  -1 for non-intersection patches.
( V6 J1 l& W5 J0 M0 H" a5 P  my-column       ;; the column of the intersection counting from the upper left corner of the
0 W. E2 ~* F1 C$ R                  ;; world.  -1 for non-intersection patches.! U1 x. s! W7 S/ O* n1 V  |
  my-phase        ;; the phase for the intersection.  -1 for non-intersection patches.
; w! f6 I- f" h# h0 M0 h! W0 L  auto?           ;; whether or not this intersection will switch automatically.
+ J6 E. h9 b& h$ o                  ;; false for non-intersection patches.! Z9 b- \" M( F8 l. S4 I
]
- s: D4 A( @. ~0 l
0 L" @. {9 `; N* E. I) l, k7 f4 G3 S9 q9 x9 ^- |* G) ?& I
;;;;;;;;;;;;;;;;;;;;;;
1 w4 W; O# p+ S: G  w;; Setup Procedures ;;& ^5 R9 _' z& t8 N  a2 L( D
;;;;;;;;;;;;;;;;;;;;;;& w$ F( A" G+ |; U- I" h2 S& W

: m+ s% b8 m8 b+ \7 r;; Initialize the display by giving the global and patch variables initial values.
( g0 G, q, W* }& A+ L7 \5 u1 }1 j+ q;; Create num-cars of turtles if there are enough road patches for one turtle to( q* y6 h. ?4 w. T
;; be created per road patch. Set up the plots.
) \& `3 Y( r/ g& A- Vto setup
  x2 g4 M" F) e  ca& `2 c7 E/ p$ G5 r* q
  setup-globals
7 h0 N2 X' j5 ^& p& v6 z# a+ n* f) v2 b* R4 X( L3 ^
  ;; First we ask the patches to draw themselves and set up a few variables
% v  C8 ~# _) @% ^7 I  setup-patches
/ ~5 K9 D" s7 I5 \% k. P: `0 f  make-current one-of intersections- J. K3 `1 ]  V8 O6 T, A
  label-current
# }; l2 m; {& U8 w0 X& x7 a+ o) o' a9 T$ i7 R
  set-default-shape turtles "car"0 W1 a7 A0 N* M' p3 C9 H

9 x- n  Q3 S6 A7 l/ }  if (num-cars > count roads)# \; F, g0 M! ]8 U# y
  [6 d5 K, @1 r+ n  o
    user-message (word "There are too many cars for the amount of ") ?1 l% b" W. ]6 Q8 w9 Z
                       "road.  Either increase the amount of roads "
/ f8 k7 B* |- I9 v+ o- o                       "by increasing the GRID-SIZE-X or ". h5 J+ J9 {9 |: N" d) x; \: Z, Q
                       "GRID-SIZE-Y sliders, or decrease the "/ g* n* ?8 Q/ Y& p& x, \
                       "number of cars by lowering the NUMBER slider.\n": \; J6 A: t# A( E2 R
                       "The setup has stopped."); y) a/ K" w8 S8 L' E, `
    stop
: k% C0 S) |+ _7 f7 d7 ^$ }  |  ]  a- w/ t; B  k, z* U) P
, d  p* ]- b" Q" n: w; ~4 X$ G
  ;; Now create the turtles and have each created turtle call the functions setup-cars and set-car-color3 k% T8 w. w* K8 [
  crt num-cars
( y: v; Z: C" p  [5 ?: A$ c# i" N4 d( Q1 r$ X
    setup-cars
, ^" U$ t$ U( W* _3 [& ?+ S4 }, \    set-car-color" O( R2 g/ @6 y: m- I- h" o" U
    record-data4 e8 D  Q, {  y% m- P8 K( M
  ]
' ~3 m* Q6 |8 K  Z- I: H
1 ^2 m/ F0 k, x/ w5 c  K! j7 h  ;; give the turtles an initial speed
! I* S( t: B$ J. {7 d' v  ask turtles [ set-car-speed ]: c5 {$ p2 E/ M5 q) d  {7 q
5 q. n. C& ~  x( W
  reset-ticks9 T$ H9 t! s% L* {/ u
end' }9 z0 _; s8 f1 w' r
) h" e) K6 ^7 ~
;; Initialize the global variables to appropriate values
* }. K& D' `3 @$ A4 o2 X, Lto setup-globals/ O! k7 }# ^# [& {, }) ^
  set current-light nobody ;; just for now, since there are no lights yet2 `) b4 a" m6 d# _, s& Y
  set phase 0
  @! |3 t9 _) ~. x0 r8 X  set num-cars-stopped 0: }) j9 B3 ]  k, H
  set grid-x-inc world-width / grid-size-x- }8 x% |& @! C
  set grid-y-inc world-height / grid-size-y
- H, Q. X' B) ]) n$ r; ~+ s$ h/ E
  ;; don't make acceleration 0.1 since we could get a rounding error and end up on a patch boundary
) T& U, p8 {2 G. N7 @3 M  set acceleration 0.099" _1 r6 K4 }# C6 n% r8 y1 b! |
end; x5 N/ n2 U7 p2 `0 L+ @' c7 m4 K

0 i4 f" L: P9 B2 V5 {;; Make the patches have appropriate colors, set up the roads and intersections agentsets,* q, K3 H  J! T* S2 f; F
;; and initialize the traffic lights to one setting
: Z- X( k5 T6 G9 v$ O9 Cto setup-patches
2 k6 e+ m7 [5 T- t  ;; initialize the patch-owned variables and color the patches to a base-color
: q+ W- D# L% y8 p2 K+ q  ask patches; D. d. ?. B/ z- L! @9 b8 `; i
  [% H5 V4 K0 F% i6 @2 b
    set intersection? false' C: d9 ]3 z! P( |$ p; V
    set auto? false5 Z9 D7 P" F) Y3 O6 `0 }
    set green-light-up? true
& \  h6 f0 i, |# }5 T    set my-row -1
1 W; j  X6 D3 D! a. U    set my-column -1
: B' w6 t% q; [0 k  G# K    set my-phase -1
  R0 V- b& s6 Q- L1 v2 A$ ^    set pcolor brown + 3
! a) j3 l+ X1 m( d: Y& [8 C  ]  E9 R) ?1 J) K* p

6 S+ u1 X" f: }. o2 m$ Y1 c  ;; initialize the global variables that hold patch agentsets
3 q2 o7 f7 N7 f  ]4 O  set roads patches with
/ v, P6 ]2 N: t1 k    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) or! i" `; f; {. M9 v& \
    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]0 I) N9 K; M) x% w9 c
  set intersections roads with0 S: n) J& N$ B( d0 O1 }
    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) and
* a' ?3 o3 c5 Y    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]) s9 v, h9 ~+ X3 F7 J
* ~1 Q0 k5 a4 J
  ask roads [ set pcolor white ]
% [, ]9 O6 t' ^" [: L    setup-intersections) X: S3 G& S# I
end$ N/ Y9 A; i  X" w4 m! ~
其中定义道路的句子,如下所示,是什么意思啊?
  C; e0 Q- K! A set roads patches with
0 l' A" V' ~1 v6 z" J    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) or
1 E4 s- D0 d2 y/ v" u, a    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]
  m" Y& z! R9 z* Y5 L3 a7 g) G/ c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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