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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。, `: b, |+ C6 ?& }
netlogo自带的social science--traffic grid这一例子当中,$ n' M9 ~( h6 l$ D  o
globals
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  grid-x-inc               ;; the amount of patches in between two roads in the x direction
# _) k' y9 D" l( X  grid-y-inc               ;; the amount of patches in between two roads in the y direction
& A* Z& C0 t0 {( `1 C7 j  acceleration             ;; the constant that controls how much a car speeds up or slows down by if$ a  h7 K0 N) r
                           ;; it is to accelerate or decelerate
. r# R- Q% X6 ], s  P6 T5 b7 S" L7 T  phase                    ;; keeps track of the phase# P6 L0 X  R2 D& \0 a& E3 J
  num-cars-stopped         ;; the number of cars that are stopped during a single pass thru the go procedure. x# ?" E" M- O% s1 K  g
  current-light            ;; the currently selected light
& w' ^# w. G1 k, r/ o
+ }8 U% g+ q& a1 y  ;; patch agentsets2 ^* H' H% w2 {, M8 G" L4 g
  intersections ;; agentset containing the patches that are intersections  ?8 M2 f# c: ?7 Z0 y- w
  roads         ;; agentset containing the patches that are roads7 y: D, S/ X7 s6 p7 J4 Z
]$ p5 d/ B* x* Q2 I, }$ r, k/ N

9 l6 q1 m% Q5 X3 h/ |; n9 Mturtles-own9 F; Z3 X) H5 g1 \$ h7 x
[# C! [, Z$ y% x7 ~' Q4 m9 H/ G
  speed     ;; the speed of the turtle1 Q) m3 Z& {* _  y6 ?* O
  up-car?   ;; true if the turtle moves downwards and false if it moves to the right
1 ~/ X! T' N8 S5 x/ s4 A  wait-time ;; the amount of time since the last time a turtle has moved
* L# L! U% F; c$ ]  q# m]
/ N+ d0 C* v/ M
6 [, v. W% t5 gpatches-own1 A9 l1 ^) J9 r& }/ l% r
[" g' n& W9 e1 [
  intersection?   ;; true if the patch is at the intersection of two roads3 y5 [0 V5 ~. b  f
  green-light-up? ;; true if the green light is above the intersection.  otherwise, false.
; `) d  A9 ~+ a( B( c5 {1 M                  ;; false for a non-intersection patches.3 E% A3 p- t, E: y; Z. P
  my-row          ;; the row of the intersection counting from the upper left corner of the
1 Y6 m1 ^' H, N9 S. R9 P& c                  ;; world.  -1 for non-intersection patches.
/ K8 G% p3 B5 d* M( u  my-column       ;; the column of the intersection counting from the upper left corner of the6 G7 I" }7 W# c; L6 V  F6 e
                  ;; world.  -1 for non-intersection patches.& k# m& N4 F- x# K' h* {
  my-phase        ;; the phase for the intersection.  -1 for non-intersection patches.# ^4 ~# s6 T9 `4 n% N; {
  auto?           ;; whether or not this intersection will switch automatically.
9 r2 Y3 `: W# ~+ `                  ;; false for non-intersection patches.
& t0 e1 Z  ]+ E) k: S8 S8 I]
. ^( z' x+ k$ _6 s! O9 Q5 I) E/ H# {& [) ~/ S; {. H
2 O" R# W: I9 R, L% m5 h+ S/ z
;;;;;;;;;;;;;;;;;;;;;;
. {9 c& s9 c8 E+ ^( Z0 P& H# d3 v;; Setup Procedures ;;
, k" N8 @5 s& Y6 P7 g0 @# l; D;;;;;;;;;;;;;;;;;;;;;;+ ~2 _$ [8 u8 R* b9 k

6 q( k! X) i. }: [/ C7 _;; Initialize the display by giving the global and patch variables initial values.3 Z6 F4 H9 E. V; B& v0 U
;; Create num-cars of turtles if there are enough road patches for one turtle to  Q' h5 r- Z$ F. [2 A* I
;; be created per road patch. Set up the plots.4 f+ z9 U* i" W# M; k& Z9 \
to setup
, F7 `2 L9 W8 E( X, I6 X  ca  i( \% ^: Z1 [
  setup-globals
; O- u0 J7 a& g4 t- B/ H8 d6 X: S% f: g) m0 @
  ;; First we ask the patches to draw themselves and set up a few variables
' E9 n: Q+ T* c0 X- Y9 v( @1 _  setup-patches
$ b+ j9 e$ c, L0 W; S6 S  make-current one-of intersections
+ `8 L( E; j, S  h+ K* t. x  label-current
; \! N6 K+ j1 L% X  w
( N* V% q2 q) q, K) s; d  set-default-shape turtles "car"
4 B0 |2 P2 z; d' Y, w
2 z0 R' D7 ?8 G  q& {2 h  if (num-cars > count roads)
/ f$ V* j$ P6 [  w* o% K  [
) [& o' n) M( Q2 N  r    user-message (word "There are too many cars for the amount of "2 }% O" f' }2 g+ R+ e0 n+ D" e
                       "road.  Either increase the amount of roads "9 t, ~9 l& X1 u
                       "by increasing the GRID-SIZE-X or "
* y: q1 {; ~- L, g3 R                       "GRID-SIZE-Y sliders, or decrease the "
# |; @# }/ B/ L                       "number of cars by lowering the NUMBER slider.\n"
2 G# I3 i# Z$ E                       "The setup has stopped."), O. ]) C3 `$ b6 }3 k
    stop
! f- Y( T0 k5 S  ]4 Q. v- L& S5 F6 g4 ^7 i, s* ~9 S
  }7 a2 Q* x: D; B* p- W4 @) P
  ;; Now create the turtles and have each created turtle call the functions setup-cars and set-car-color
% v: Q8 q9 G& h( x  crt num-cars
8 Y" G5 \. Y: e  c# ?9 U" ^; o1 ^* u( A  [
+ v2 ]/ H2 a: R4 ~6 I! `( v    setup-cars
3 W* f0 p) ^- O% a; ]# \    set-car-color' b6 w( P& N0 t  s% I3 r/ j
    record-data
8 U$ @! [, F$ [, h! \7 A  ]
% f, }2 B! F* C! L
7 S* Z4 u  G0 ?6 i" ^4 W! x# s% ]  ;; give the turtles an initial speed% K3 z& D( G% x8 `3 {# V6 J: L2 W
  ask turtles [ set-car-speed ]
% c- p' ^3 h4 Y7 ?' d6 O" b4 r6 y# j; s* U4 F
  reset-ticks' Z* L# ]1 R, O+ A, ]: v, u  e
end
1 Z- U% F7 X% Z  l2 m: I8 L! e% D1 ]
;; Initialize the global variables to appropriate values
$ D% s0 W8 T9 h3 a3 a2 L# Ito setup-globals
3 Z4 h. q% D, r" |  set current-light nobody ;; just for now, since there are no lights yet( s' V$ z1 s; ]' l. ^2 O
  set phase 0
% s$ G: Q# y/ h" c; j+ E; u6 _+ J  set num-cars-stopped 03 D/ S/ s; |4 G1 |
  set grid-x-inc world-width / grid-size-x4 S& D5 a8 {0 p! `% Y5 Q% M! _
  set grid-y-inc world-height / grid-size-y
' [7 E: x! ]5 @$ A3 F4 j" P) j5 j& ?8 u/ J
  ;; don't make acceleration 0.1 since we could get a rounding error and end up on a patch boundary
: O( M. A) h4 I0 q& G" {/ J  set acceleration 0.099
5 `3 _# f! V! a( K& q, Lend! s! m; v$ {7 n# W
# J, s" _+ l+ I/ Z7 G( R0 c# @, h
;; Make the patches have appropriate colors, set up the roads and intersections agentsets,
' o9 X  P* m3 n# @/ p;; and initialize the traffic lights to one setting
' Y" C" ]. Y% ]9 K' [3 I& Y5 Cto setup-patches  E1 }* c, C5 U3 O: Y/ X
  ;; initialize the patch-owned variables and color the patches to a base-color
- ?9 H5 b2 c( b8 T7 D- P  ask patches
! U) H" l/ |  E1 V- w4 Z  [
) D( R6 k. J6 \3 K3 e& y" [) w    set intersection? false
; {$ V' p6 e: t0 j: x% e! ^7 [    set auto? false& R2 m5 }: ?7 i
    set green-light-up? true
5 E0 Z1 Z  B% `2 o1 Q    set my-row -1- j- u7 e* C( o2 U6 b% M
    set my-column -1
8 \$ [4 p' _8 Y* `* h    set my-phase -1
3 O5 H3 ^+ k1 k3 r    set pcolor brown + 3! p) N& w2 f4 R) j
  ]
/ ]9 w: k. e9 M: r4 o" T8 R% h# f8 X7 ?3 Q/ d
  ;; initialize the global variables that hold patch agentsets6 F1 i) w2 U/ B0 m' b
  set roads patches with
1 X* M' B  o2 x1 Q    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) or) z& M0 M! r: k. p* Z7 y
    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]8 W; S) O8 b1 D9 A
  set intersections roads with, R( E, I% o) R4 y7 m; e5 J) R
    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) and$ }" D5 L- v1 m: J+ o
    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]+ G9 M7 j$ J( {' N/ U% L4 o# @

/ E. u* X9 _9 `1 G7 f3 }  ask roads [ set pcolor white ]; W+ q) A. v5 X$ q
    setup-intersections
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其中定义道路的句子,如下所示,是什么意思啊?
, O$ t! t0 {& x  X set roads patches with- ~$ U4 n8 V  `& }4 J. u& L
    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) or
- u6 B+ x; D$ P3 i: t6 G    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]9 r% U5 R/ b  [: y
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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