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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。/ L! K$ X" j/ e4 g4 W/ s7 P, o
netlogo自带的social science--traffic grid这一例子当中,
* N2 f$ f5 N, v0 z" @3 Cglobals
$ l: q8 x+ @' X[
- Y5 G7 [0 K; o# }5 X9 S1 C  grid-x-inc               ;; the amount of patches in between two roads in the x direction  E' o3 z3 q! I' h
  grid-y-inc               ;; the amount of patches in between two roads in the y direction$ B3 B: w+ ~( R9 V/ @1 T( q) t6 n
  acceleration             ;; the constant that controls how much a car speeds up or slows down by if
1 x) L  h6 B8 k6 N                           ;; it is to accelerate or decelerate
! R: {. K' Q+ t& C+ E1 q9 m+ N  phase                    ;; keeps track of the phase- b: V3 X" s. B
  num-cars-stopped         ;; the number of cars that are stopped during a single pass thru the go procedure- e; F# @" j8 V! M
  current-light            ;; the currently selected light, ?. P, E0 Y2 @* R0 U2 S) X
6 I5 Z2 T: Q- u5 _2 h+ C$ @0 O2 J
  ;; patch agentsets
' x9 k5 g# h3 P/ ]4 b5 K6 n  intersections ;; agentset containing the patches that are intersections
' V2 [6 x6 p; y' E3 E! r5 B8 {  roads         ;; agentset containing the patches that are roads
9 ]+ ~" [) Q) Q" w]
* l0 M4 i& b- r$ [  t+ J' \4 _6 ?. t: B
turtles-own
; |- _1 B/ b6 l' w, \) W' k[" A1 r1 R3 V% l+ |+ l9 c' G
  speed     ;; the speed of the turtle+ Z8 _2 X. g/ P, i6 Z
  up-car?   ;; true if the turtle moves downwards and false if it moves to the right3 b! [! E/ Z5 q6 v5 r
  wait-time ;; the amount of time since the last time a turtle has moved
: E2 O7 X+ [: W4 W% Y]
7 g8 b; s; H; `
$ C+ r2 T) U0 k7 H3 ^patches-own4 ~5 C/ i  O1 k( d1 l
[
3 `: x( k5 _9 \, r; ^  ~, D  intersection?   ;; true if the patch is at the intersection of two roads
/ W$ y! C+ h6 h/ b. ^  green-light-up? ;; true if the green light is above the intersection.  otherwise, false.  ]  b9 I4 L. V0 Y5 @/ e/ S
                  ;; false for a non-intersection patches.: |" L! m, i' Y* k$ l6 }$ K
  my-row          ;; the row of the intersection counting from the upper left corner of the
% O1 a. G% \- l; w+ S- ^: k8 f- D4 {) V                  ;; world.  -1 for non-intersection patches.+ r5 U4 o  s+ o
  my-column       ;; the column of the intersection counting from the upper left corner of the
8 x) \; j1 O0 x% k. \0 O, a3 V                  ;; world.  -1 for non-intersection patches.* b, f: n1 x" Z' d
  my-phase        ;; the phase for the intersection.  -1 for non-intersection patches.
0 T* P- E) z6 ~  auto?           ;; whether or not this intersection will switch automatically.
# K  t9 F2 E6 b+ l3 d- X' j) j3 g                  ;; false for non-intersection patches.
3 K) R0 s6 [3 X0 Y& [; C& S. E]
3 t  a2 ]! @+ N, p1 [4 m
0 p, k/ S) s; B7 b( a" B2 Y) C) o3 p6 C+ {$ C; U+ [5 |; g4 S% J* e
;;;;;;;;;;;;;;;;;;;;;;
2 u* {# a: Q! J$ |) F;; Setup Procedures ;;
3 t3 g" I$ i; U- ~4 n6 `: @;;;;;;;;;;;;;;;;;;;;;;
/ `' l4 I9 `9 t3 `; q
! S4 _, @" B& `8 r;; Initialize the display by giving the global and patch variables initial values.
# f6 E9 S# K5 D% L& L& z3 F- N;; Create num-cars of turtles if there are enough road patches for one turtle to
. |- A0 g  |# I- N;; be created per road patch. Set up the plots.
8 W1 g  C  N$ g) |: rto setup
& j" s  V! p3 P* \; V$ x* I" E  ca$ Z# b# ?+ g- y$ H( h2 |
  setup-globals6 e( G+ }5 p- U: F4 O5 @4 B

3 ~2 x7 p& [/ G" ?) U' z9 L# [- R  ;; First we ask the patches to draw themselves and set up a few variables
( n) \4 u$ U. |% d  setup-patches
2 B4 b* W! j$ T: C  make-current one-of intersections
% ~5 d* n+ C/ Q# O5 g  label-current) w7 x* T# ?5 f  ]) X# G
9 F9 Y/ }. V) ^: K0 `$ \
  set-default-shape turtles "car"
* K" n7 c; h, n: c4 W4 x
# x6 |; Z( }# e  if (num-cars > count roads)$ g8 s5 |& D+ d5 ]
  [
+ L7 [9 X1 p; v    user-message (word "There are too many cars for the amount of "
, }9 S# f' t3 X" N7 J- F                       "road.  Either increase the amount of roads "
  \5 y( j) U* R7 }                       "by increasing the GRID-SIZE-X or "$ W# ?  Q( _* B! Q3 r0 g* O1 d
                       "GRID-SIZE-Y sliders, or decrease the "
* {/ k) ^% s8 B4 V% ?! h9 I                       "number of cars by lowering the NUMBER slider.\n", \/ R2 @+ B) m1 n9 R$ M) a
                       "The setup has stopped.")* J& p9 a* `' G( `9 i* k7 Q/ a
    stop
- n0 Z4 R9 ?  \# D8 x3 e  ]
7 W1 m, ~! H! c" t
  ]& G# g; s1 j  ;; Now create the turtles and have each created turtle call the functions setup-cars and set-car-color% x# Q9 C' h/ U; m0 H, A' y" g& w
  crt num-cars
( q9 ]# n; g. t" ~5 ^0 O  [5 x- L; {! Q9 E2 n* ]) ?1 Q
    setup-cars  O5 O- x) h( q7 @9 K4 g; P
    set-car-color
& X2 o1 D# A! m$ i3 I    record-data
& m' j7 G' p7 @; k8 Q  ]1 ]1 f5 Y+ ^0 h1 J5 z5 U& O% Z
' N8 K4 y4 f& ~$ t7 W: i. V
  ;; give the turtles an initial speed1 m+ @! }" [3 N6 f0 x
  ask turtles [ set-car-speed ]
/ ?6 P5 E3 n3 x) ~$ n( R- C7 Y% K
3 S9 R8 v- J* u/ \: y  reset-ticks# q7 W' X4 E' Y- W, ^. L6 D
end/ q" a* M9 d4 ^/ q

3 O/ x0 v; N6 g# E0 J+ u) b5 p;; Initialize the global variables to appropriate values- h) E* s, E$ s
to setup-globals- n; X4 v2 S* F" c' ~
  set current-light nobody ;; just for now, since there are no lights yet" I6 `2 c& W/ b6 ^# Y% Z
  set phase 0
2 t" S% ?* [5 a+ B; d  set num-cars-stopped 08 i- D2 A7 l7 W$ o
  set grid-x-inc world-width / grid-size-x
  ]* o4 k6 r+ z% l1 e2 C" T( P  set grid-y-inc world-height / grid-size-y
9 w* J* G6 b2 W% r6 n0 B8 \
- l- ~1 S& S/ L4 S- `  ;; don't make acceleration 0.1 since we could get a rounding error and end up on a patch boundary. p" K5 X+ [2 c5 m( ?; m
  set acceleration 0.099
9 t. l" `0 M6 Y3 eend
  b- w  c5 j1 S$ C, r! Z
2 w7 z6 V% [7 b6 P- D;; Make the patches have appropriate colors, set up the roads and intersections agentsets,
+ V, Y' R" Q* }8 r;; and initialize the traffic lights to one setting  C; W/ ~8 H1 ~2 m4 @! i; x
to setup-patches$ Y7 U3 P/ i; Z- F
  ;; initialize the patch-owned variables and color the patches to a base-color
+ R1 Q3 F6 }- r4 Z" A  ask patches1 q- o, J$ z  r
  [
; s5 r/ c% P6 S, }& D    set intersection? false
* C# d' W& X( }; W    set auto? false
' ]# j" m# \% d4 c    set green-light-up? true
8 @  O( f) L. h% X, K3 p    set my-row -1. W) O6 f, ^  v$ v. @4 ]7 J
    set my-column -1: p: R! z: ~; s
    set my-phase -17 x9 Y4 }2 Z* l# l9 d
    set pcolor brown + 3
- k# ?5 a+ F: H) U# u  ]& n/ S; s2 s: O

: n! O& h$ c9 B9 n2 t. T  ;; initialize the global variables that hold patch agentsets/ y. w1 P4 i0 P% d" q0 J! {
  set roads patches with/ T+ U( z* h: \6 N
    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) or% s% r& Y% D6 K8 Q: Q% a
    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]
! C8 U$ E1 S; R) a  set intersections roads with# T! N' O( R. E/ k7 K
    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) and
. ?: O" R3 C5 r; Y8 W  b0 t    (floor((pycor + max-pycor) mod grid-y-inc) = 0)], [1 _$ g5 E' {9 _/ G' V& u

9 l; {( s  y, T0 n5 ^; T% u  ask roads [ set pcolor white ]
5 {0 u/ C, F: ~& S    setup-intersections
/ _; }, Z- E) R2 ^) T1 bend
) t0 `; e& g; R9 C" y其中定义道路的句子,如下所示,是什么意思啊?7 K/ R: l$ ~+ N* m
set roads patches with
" ]' ?- Y. ?3 i5 X3 s. h    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) or
) C$ I" O' n6 G4 E' t/ T$ D    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]4 B) z# N% m2 q2 p2 f
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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