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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。4 _' ?8 ]# d' L( t! s0 l
netlogo自带的social science--traffic grid这一例子当中,
7 \, ?. s, `0 j& _globals
  b( c- W3 G# f2 o, _& F4 \1 H$ q[7 O& ?& M3 D% e
  grid-x-inc               ;; the amount of patches in between two roads in the x direction5 [2 d- o/ |$ ]# c
  grid-y-inc               ;; the amount of patches in between two roads in the y direction% x5 v6 S6 o6 o! y8 ]% w3 e; Y
  acceleration             ;; the constant that controls how much a car speeds up or slows down by if
! l. I6 U8 l9 p) O- g4 U                           ;; it is to accelerate or decelerate/ n, H/ l5 @+ r2 n* Z
  phase                    ;; keeps track of the phase
6 F7 g" F; ?  C  Y  num-cars-stopped         ;; the number of cars that are stopped during a single pass thru the go procedure: B( H% H( ~7 r' O
  current-light            ;; the currently selected light
9 J2 T  `  `4 t1 B/ f2 W( ?& V. H3 v2 E9 G8 A: ?% v) J5 |
  ;; patch agentsets( H/ v: U  `9 K$ G8 m% t0 e9 }
  intersections ;; agentset containing the patches that are intersections7 [& |8 G/ @0 g% {5 ~2 n" Y% K' c! _
  roads         ;; agentset containing the patches that are roads$ q9 n) Q: D: w: o3 F8 `
]; i7 Q* Y: r3 V/ n: o& ~0 E% K

& V& ?0 m  ^7 ?% ^- Y; r0 _  A  aturtles-own: N, J- f' `; {0 T2 ?$ G
[9 i( `+ e# v. Q& t8 o3 Z  B& @: Z
  speed     ;; the speed of the turtle
( |6 X9 k9 g0 M# x0 t' O  up-car?   ;; true if the turtle moves downwards and false if it moves to the right
/ n7 O$ ?3 A0 N  [2 n" x  wait-time ;; the amount of time since the last time a turtle has moved
& M* u' s; v9 J* k3 U' o]
; C! n2 c( f% E7 S2 r1 A. m0 x+ n
( v+ k# U' F, V2 I0 i" Gpatches-own
- _3 e  m6 g! N  |% P6 r[
" @: S; \8 m: E( G5 B5 O- K  intersection?   ;; true if the patch is at the intersection of two roads
0 N8 s4 a8 c% f2 T* V2 c  green-light-up? ;; true if the green light is above the intersection.  otherwise, false.
/ ~; G( J' a1 z                  ;; false for a non-intersection patches.
) N6 }# L2 Y# b# [5 O8 u  my-row          ;; the row of the intersection counting from the upper left corner of the4 t0 f  Q2 a- E" \7 c3 l. G6 Y
                  ;; world.  -1 for non-intersection patches.4 M& A+ p- s2 l) a5 I
  my-column       ;; the column of the intersection counting from the upper left corner of the4 R: ]9 y7 x2 k
                  ;; world.  -1 for non-intersection patches.+ d1 s! E6 S7 P4 q% o5 m/ B
  my-phase        ;; the phase for the intersection.  -1 for non-intersection patches.
% h, X( H& o4 S: s  auto?           ;; whether or not this intersection will switch automatically.- |0 K' N5 F( v. O
                  ;; false for non-intersection patches.
8 T$ s3 j9 O) ^6 j2 T]8 L! F2 x5 o/ Z. b' @) U. G. L
9 c5 E% L+ ~$ N! p  q
* y& Y; d4 r9 I; m: f& H
;;;;;;;;;;;;;;;;;;;;;;. O  `( ^! u6 j! f8 g- b
;; Setup Procedures ;;2 D  M5 e/ w' s% j/ U8 B
;;;;;;;;;;;;;;;;;;;;;;
' M* e& a0 ~! R- u2 _# E: y8 P  X$ e; s# }3 u5 O
;; Initialize the display by giving the global and patch variables initial values.6 t: H0 T0 q8 ?8 o# ?) Z, C6 X
;; Create num-cars of turtles if there are enough road patches for one turtle to
; p* |- ?0 q3 N;; be created per road patch. Set up the plots.( J5 L# \! k8 b
to setup
' z+ b! _  \+ u0 A' e  ca
8 B! K& a7 S: V* L7 q# l  setup-globals" n# n8 T8 v& S

4 w& L" I* R3 C: ?) ^4 Q  ;; First we ask the patches to draw themselves and set up a few variables
! V- E' J+ Y  b( m8 J) `  setup-patches
) v7 y9 H7 J: e) y2 {% n, M  make-current one-of intersections
- r  w3 n# F2 i7 G) f  label-current: U' c& J$ }) d- @3 g- u8 b
/ Q' B: _, b: Y$ X
  set-default-shape turtles "car"
/ c5 \1 O4 I: O$ t
; s: I/ r; N, Q: B. R4 Z) M  if (num-cars > count roads)* b% ^/ k, _' u  M+ P- Y
  [! |% M! g1 L: N9 G, q
    user-message (word "There are too many cars for the amount of ", p6 b& X: {8 J: h' U
                       "road.  Either increase the amount of roads "4 _5 v2 [! ?" [- E7 I5 \! Z! M
                       "by increasing the GRID-SIZE-X or "
# M, l# J4 v/ p9 O7 c+ q" \2 [. V                       "GRID-SIZE-Y sliders, or decrease the ". c- J1 y4 p4 M: j
                       "number of cars by lowering the NUMBER slider.\n"
& J* A* T3 C# ?3 ~                       "The setup has stopped.")
# i# f: m% ~& A# k/ j+ t    stop
  K/ }" F6 ~% r7 ]# H2 t% E2 e0 C; D  ]
3 T- c5 F6 R1 v/ g) ~
+ E' a; I3 x9 D' A9 W: \; G  ;; Now create the turtles and have each created turtle call the functions setup-cars and set-car-color
% h1 x4 |3 {* [3 M! z% l+ A: o  crt num-cars
* b+ Z3 C5 M. |8 w  [
+ a& c  ]2 ?2 a3 a) }    setup-cars$ Z! A' ]8 m( A/ n0 c
    set-car-color
( ]! o0 C4 H& c" k, Y1 f    record-data4 P) l7 B, Z3 F, ~' b( t4 B: t
  ]
2 s0 Y1 s. N; e. R4 M: I
# Y. ~. \8 c( O- w6 m' r( k  ;; give the turtles an initial speed  _2 B9 ]' g5 P5 c" c
  ask turtles [ set-car-speed ]
9 V& l6 P. n  Z2 t
/ \# W0 C5 [( j* ?3 Z+ X- v  reset-ticks
1 j/ P  Q7 R# e+ mend
6 }: d; Q& \: B! V" ^1 p: W  y$ W# K6 k* N+ l( L' |
;; Initialize the global variables to appropriate values
0 @4 W* c9 i+ Z% eto setup-globals+ K2 B7 [8 _+ H" p" K- H# O
  set current-light nobody ;; just for now, since there are no lights yet/ s- J9 B$ D/ W- T8 W) ^+ Y2 k
  set phase 0) X* F, p6 o# ~. E
  set num-cars-stopped 0
8 Z* V! S* U- I& f- P$ q# x" _  set grid-x-inc world-width / grid-size-x
  I/ L9 x  H) X; _% W  set grid-y-inc world-height / grid-size-y
2 {0 X' v6 d. E6 z6 O5 b6 F/ v9 [6 D
; T9 y# Z( r+ |0 N  ;; don't make acceleration 0.1 since we could get a rounding error and end up on a patch boundary
  M' ^, U( X4 U! L4 b/ [- R  set acceleration 0.099
8 {: G* I2 e0 [8 qend1 h0 d: n% G- f) W) F

6 A1 a% g  s1 I8 m* a3 p;; Make the patches have appropriate colors, set up the roads and intersections agentsets,
5 H4 G' O9 D# c  N; k;; and initialize the traffic lights to one setting
$ ^. R' y( Y8 k6 {to setup-patches1 r4 k) ?: ~, @& W* s3 t% |; l
  ;; initialize the patch-owned variables and color the patches to a base-color
0 U) Y/ d3 m1 S2 E! v/ q  ask patches
; ~9 p, n# R7 t* i+ c2 u# B; B  [' g" D6 F( G( P8 ?: [8 T
    set intersection? false; B" K. I: s+ d+ o
    set auto? false
& j  `2 a7 |/ S5 e    set green-light-up? true
& u) v7 i. U: s' j* j9 {  V8 \8 n    set my-row -1
0 F$ J6 E1 G& C& h    set my-column -1* @4 j5 s$ H: K  Y
    set my-phase -1
4 L3 A( I0 H' P8 }, i2 s; O4 y  V9 y    set pcolor brown + 3
* A! i5 m5 i7 x7 g  ]1 k/ V# Z# x3 l' [/ ^2 I8 X
. L) N% a! f. F" U8 _' k
  ;; initialize the global variables that hold patch agentsets0 \2 u& p4 v( ?. v+ A7 V+ E  P
  set roads patches with: X' s' P2 p# ]  [0 q! |5 ^
    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) or
3 d+ B' I  f8 ]( t    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]* k( @3 ]& w; G# A- G
  set intersections roads with7 |% m/ @" \* q4 x' Y! X
    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) and1 P* q8 H# ^) Z. c. K8 r3 S6 G! C
    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]& Y/ X7 y- p7 Q# z2 k: T) N
8 O7 N/ t) B  ?4 N+ a
  ask roads [ set pcolor white ]
* r3 F' E5 ~+ `7 G, g( Q. I    setup-intersections; ^5 t$ S: C# q  O
end; N; y5 u0 k$ _3 Q& E" u/ \0 x+ ~7 B
其中定义道路的句子,如下所示,是什么意思啊?
. }0 S) u9 Z/ u3 Q- y1 D7 e set roads patches with1 u" P2 K4 C2 q  o6 C
    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) or
! K( ]9 }) q% j% I4 t    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]% f1 K  H& h9 [! R# u# ^" C5 ^
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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