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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。/ ~0 Z8 U2 [* z' F& p0 U1 R
netlogo自带的social science--traffic grid这一例子当中,
7 S1 S2 W* Q. k* y( Gglobals
3 j; U9 J6 N6 q[0 J5 P+ b  N2 d4 g% }3 y
  grid-x-inc               ;; the amount of patches in between two roads in the x direction0 [6 H& X# X, n" F$ J! J1 P
  grid-y-inc               ;; the amount of patches in between two roads in the y direction  l- D. N. \% \: M6 c
  acceleration             ;; the constant that controls how much a car speeds up or slows down by if2 O) a' }" k6 @+ c
                           ;; it is to accelerate or decelerate
# Y3 ?  q" `- Y' j  phase                    ;; keeps track of the phase
0 ~8 w& ^% G( s( N  T  num-cars-stopped         ;; the number of cars that are stopped during a single pass thru the go procedure" N" B7 d/ E; R" |$ w
  current-light            ;; the currently selected light
7 ?: V" k6 M; A) W& G' ?5 C, \+ ^! M6 `& |+ P. w
  ;; patch agentsets0 a5 ^8 d/ B. ]
  intersections ;; agentset containing the patches that are intersections
/ E; J2 ~$ [' e: P. {' g  roads         ;; agentset containing the patches that are roads0 J/ V* H4 U" e3 J. x, w+ v* a
], p' j! m$ l. g' u0 g* `

) p) M5 ^" g0 yturtles-own9 H7 ?) X; w- d
[
" E: C  e6 a& M! q9 f: S  speed     ;; the speed of the turtle% w3 b" P5 ^+ E# C  x
  up-car?   ;; true if the turtle moves downwards and false if it moves to the right4 x9 R) l0 s; t. X& X) B5 h4 c
  wait-time ;; the amount of time since the last time a turtle has moved
9 W1 r( E5 I9 M& P! K1 i$ V2 f], i6 ~1 [, `& A* a0 t+ m
  X7 E$ O/ R. C1 E9 N9 A
patches-own- M) e# s% V& C  v
[
8 l# V3 t% X( g4 @9 F4 `  intersection?   ;; true if the patch is at the intersection of two roads
* {- H' J8 R+ M# |; [$ V. d  green-light-up? ;; true if the green light is above the intersection.  otherwise, false.7 w& b6 a  b/ Y
                  ;; false for a non-intersection patches.7 r* ^8 i8 a+ T% q
  my-row          ;; the row of the intersection counting from the upper left corner of the: u! H  a- C+ w; V4 g
                  ;; world.  -1 for non-intersection patches.& P( V( p9 [- m1 K. a/ `" N
  my-column       ;; the column of the intersection counting from the upper left corner of the
8 N& n) O! F% [, i8 ^! P3 v! v                  ;; world.  -1 for non-intersection patches.5 k' V( c2 r! b3 P
  my-phase        ;; the phase for the intersection.  -1 for non-intersection patches.
  O  j  N" @7 C; j0 ]# a: k  auto?           ;; whether or not this intersection will switch automatically.: I# w- H* D- k0 B% m! z+ r2 q
                  ;; false for non-intersection patches.
# d' L! {, B7 ~( N8 w  ]) j# y# ^]
2 x' q1 k; c+ M1 r- p3 r
0 |6 s+ ?( f4 w% H+ ~
: {) c- q* T/ |" ~5 n6 V- ^9 `# i0 u;;;;;;;;;;;;;;;;;;;;;;
" u' x' T7 t8 G8 V. @  l" |$ j3 x;; Setup Procedures ;;8 b( U8 W! i5 Q& H/ i8 C
;;;;;;;;;;;;;;;;;;;;;;
+ ^0 e$ Q& w7 i4 o" k
. V4 o: x, q, E+ m+ a+ v4 Z5 e;; Initialize the display by giving the global and patch variables initial values.
7 O# P  H- ?8 Z! K# ?3 J* E;; Create num-cars of turtles if there are enough road patches for one turtle to* C! [* T" M! y5 m$ J3 G
;; be created per road patch. Set up the plots.
) `1 A7 s# o) A3 |to setup
* Y0 C4 U2 E! s' m( J4 ]- g/ F  ca
) Y7 M0 y' l+ d1 Q0 Y0 `  u; b  setup-globals8 Q% B+ [4 O  ^2 d' A5 E

1 y8 e# e  F% X1 x- r  ;; First we ask the patches to draw themselves and set up a few variables
- e( I/ m* F' A% u  setup-patches$ U, _7 E+ ]! Z- y+ D) I
  make-current one-of intersections
( D3 l0 b" B* |; h( x  label-current
' T: o# i0 I) n; k* l, F+ \- O9 ~4 I* o: B
  set-default-shape turtles "car"
* Y% I: C/ v' }8 b  z& S( S2 `, Z6 Y
  if (num-cars > count roads)
( T: [2 n# L9 H  |  [
$ M) w$ @0 \; i$ H( @9 D; P    user-message (word "There are too many cars for the amount of "
+ L2 Q3 y3 N4 g% k: ]4 X5 e( i                       "road.  Either increase the amount of roads "
: u3 s# h" G' ]! {                       "by increasing the GRID-SIZE-X or "
0 o  m2 P% d6 {* f                       "GRID-SIZE-Y sliders, or decrease the "
: f7 J; ^8 c7 m$ J7 `                       "number of cars by lowering the NUMBER slider.\n"
, c, y% D) \$ f8 \% W  Z: w3 |                       "The setup has stopped.")
4 N: V3 D  I# o    stop
- s, K; ^3 Z3 c. M  ]2 ]$ R# f1 R8 {

9 `  A7 s4 o9 i% S. K, P4 `3 ]- i  ;; Now create the turtles and have each created turtle call the functions setup-cars and set-car-color) |; E( l! j+ Z. \9 F% ]$ W
  crt num-cars8 |6 d% y2 D) W
  [
" F) Q$ s' }& K6 ?8 x    setup-cars
% `: Y* m+ s9 E+ P% P( O% G( k, M    set-car-color# d! W* {0 ?$ l9 n' {
    record-data5 \4 m8 f! H6 E. p! m8 [
  ]
4 p" O  j7 f" M4 R+ B- r5 A
2 y+ r5 h, @% d  {& t  ;; give the turtles an initial speed" ?" H/ n' t$ K5 x% H* G: Z  \- G* {, m
  ask turtles [ set-car-speed ]
: R; [/ j, i, e1 x$ i  @- r, s; c3 \
  H6 ~, k, O1 P6 V  reset-ticks
, Z/ z# r# K# y9 ?6 Cend: k# Z; a" m* j6 t! a
# t$ y: F' V; X! Q' e
;; Initialize the global variables to appropriate values
, W( p( Y! ?5 d, W( S* |to setup-globals% X1 |% Z. q. \2 m
  set current-light nobody ;; just for now, since there are no lights yet
& q" k3 M. F; \7 ?  set phase 0& P1 ~2 a' F. x  F( j5 S
  set num-cars-stopped 05 m# c: ~7 x" z4 L# n) K7 ~
  set grid-x-inc world-width / grid-size-x
2 ^1 ?7 s  |! a2 P+ u3 o3 g  set grid-y-inc world-height / grid-size-y1 x! Y  s( V# j1 A, ]% Y; `

; N4 \1 d6 R+ S# u  }( {( l8 k  ;; don't make acceleration 0.1 since we could get a rounding error and end up on a patch boundary
/ O4 l2 [( v7 r8 [  set acceleration 0.099
( g, t# s6 }- Q. Z; `end, v: X9 g8 h- ~

" B9 D4 \! O% C, w;; Make the patches have appropriate colors, set up the roads and intersections agentsets,  s, W' {3 d" @' y; b
;; and initialize the traffic lights to one setting9 g3 C) g7 Y3 O  Q+ u- C6 n
to setup-patches
! i3 F7 V. m% _2 R3 E4 r' o7 W  ;; initialize the patch-owned variables and color the patches to a base-color
% V! c- L: B! @  ask patches* A; e$ t% R* B5 w) L  V% N2 C
  [( I- ], v" ~4 ~9 b
    set intersection? false
9 j% k! g8 h, v* R- P5 u5 W    set auto? false& q5 V9 B) v) I9 i6 D. m& E  E
    set green-light-up? true5 s7 [4 z$ O4 [: [3 |4 T
    set my-row -1
: m& q/ P- D" M# j- v- J& A    set my-column -12 ^3 m* Y8 w+ u* j( \5 G0 A. _' Y
    set my-phase -1. U# ^, y: N6 }: r5 F  Q
    set pcolor brown + 3# V7 N( z- v' x9 t$ @
  ]
4 S" X# M) m6 c- @
, U1 B5 w! s' `1 {& h; ?  r  ;; initialize the global variables that hold patch agentsets+ z2 j0 r1 o* M$ c8 ~1 ]- e
  set roads patches with
, A8 k5 @( f8 J: k    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) or
4 j. R( `0 B8 O- ]    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]
$ S4 Q: U4 v, U0 C5 e  set intersections roads with( u% S5 N+ Y8 E0 p; ^2 v
    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) and5 I3 s8 U/ R& Q) Z4 W8 }
    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]2 W" N% h& k; ]8 l( Z5 j

9 P% P2 i& C+ g0 _# H9 i  ask roads [ set pcolor white ]0 F8 x  C* e( @$ K& O( N8 A6 l& I& s
    setup-intersections
" Q- E% \  v2 r, ~end$ ?: I5 ?; k4 n6 u) [
其中定义道路的句子,如下所示,是什么意思啊?3 H8 a$ r5 N8 ^# W, a
set roads patches with
, u% }' a7 h& [    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) or- N% e8 q6 c' ?6 K; _
    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]
- R$ E3 V) e! Y) Y5 K& _7 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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