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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。) {' U. e, ]1 M* R, z6 m
netlogo自带的social science--traffic grid这一例子当中,# J% ?* T1 U$ X. K
globals0 |+ y* M) ~1 u9 f; q) l
[
& s6 Y+ h, o% T9 \, V/ d8 q  grid-x-inc               ;; the amount of patches in between two roads in the x direction- X2 q- I% j3 n
  grid-y-inc               ;; the amount of patches in between two roads in the y direction1 q2 m8 ]6 Y9 d: N4 h4 H# i
  acceleration             ;; the constant that controls how much a car speeds up or slows down by if8 k/ j) R& H/ M" {
                           ;; it is to accelerate or decelerate
% o5 K9 K3 B8 R4 o  G  phase                    ;; keeps track of the phase
) p: G  o% b/ `. @6 q+ [  num-cars-stopped         ;; the number of cars that are stopped during a single pass thru the go procedure" O2 S. ~$ u5 V! Y
  current-light            ;; the currently selected light3 V, r8 G- ?4 n3 m+ Z

3 s: t! c* h7 d7 E  s: X  ;; patch agentsets
4 ]# ?9 t( w7 R2 ^! i9 F( c1 h/ t- i  intersections ;; agentset containing the patches that are intersections! W6 R$ T  \7 \, }4 H
  roads         ;; agentset containing the patches that are roads
6 j0 i! q2 E' @]
2 Z1 ~, n" |. ?) Q% J
, Q$ K6 g. }& g$ ]: d! X- bturtles-own% P! L9 T" U, h1 F
[
1 Q5 J& ^4 ]3 h4 I0 C  speed     ;; the speed of the turtle
8 b% E( o$ e: u: T; N; v, c  up-car?   ;; true if the turtle moves downwards and false if it moves to the right
1 n- d- N% ]  n  wait-time ;; the amount of time since the last time a turtle has moved
7 x, x: p0 k- F8 t) T/ e* h6 U) K]
+ L5 o' `: f* h7 s( u6 l" @6 n* P8 t
patches-own/ T% K4 L1 R5 i
[7 {2 L. L/ o. z  ~
  intersection?   ;; true if the patch is at the intersection of two roads
7 K  }. Y+ F( ]/ |- G% O  green-light-up? ;; true if the green light is above the intersection.  otherwise, false.
% ]" a* g* U7 b/ J1 y) q                  ;; false for a non-intersection patches., R6 w/ R# Z/ o
  my-row          ;; the row of the intersection counting from the upper left corner of the
9 {0 @! z! [( b7 f$ v, J2 Y, I0 ?                  ;; world.  -1 for non-intersection patches.; Z0 b* {: `4 F) i6 b% E
  my-column       ;; the column of the intersection counting from the upper left corner of the
  P& W! k# p" G+ F4 e# f                  ;; world.  -1 for non-intersection patches.
4 o) D' f/ ^6 m4 E3 P  my-phase        ;; the phase for the intersection.  -1 for non-intersection patches.
' x. X" U7 w( s% F# I: H& G/ A: p  auto?           ;; whether or not this intersection will switch automatically.2 f0 ~4 T7 L. Q9 f# A9 s
                  ;; false for non-intersection patches.
* q# S5 N8 M, V6 D]
6 c* `/ `( c* D- V& a0 u
3 O# ]" V+ d, e2 Z5 x  e2 X6 g: j% R4 [2 t- `
;;;;;;;;;;;;;;;;;;;;;;9 i1 y( l/ b) U/ A
;; Setup Procedures ;;) O+ n( |% d1 {3 r% p! F
;;;;;;;;;;;;;;;;;;;;;;& u3 ?. ]' A% N9 ?- ^$ _
& `4 g) |6 `1 G: J! }" t4 j- u* o7 l
;; Initialize the display by giving the global and patch variables initial values.
% b5 M' r$ \  C  ^, ^3 S) }: O& Q) f;; Create num-cars of turtles if there are enough road patches for one turtle to/ R7 u/ O, ?& {; k, e
;; be created per road patch. Set up the plots.( g4 }1 [( Z8 J: L' K  h1 W; R. P* \3 ^
to setup
7 B4 w3 w" O  P5 ^  ca
- q/ L2 o, i+ w( U  setup-globals8 v; T! U2 Z: V8 v% w* p; S, N1 b3 O

+ U- u. y8 ]. C' g) `* W  ;; First we ask the patches to draw themselves and set up a few variables
3 W" m+ ]6 p+ x/ k- d+ l: e- `! i  setup-patches
3 q! m7 j4 f' u' Q; O4 [  make-current one-of intersections- Z6 F$ z7 u/ N3 K* q2 a
  label-current& e- Z4 S. ~/ K1 \
, F2 F/ z) D2 s% r( O
  set-default-shape turtles "car"* i8 |( Z8 E/ ]" g/ B7 M: {# B

% g$ }6 b. z! \* @# N+ B4 v7 U" O  A  if (num-cars > count roads)/ c; L# d8 J/ g/ C. |/ P
  [8 p- }- _# e! ^
    user-message (word "There are too many cars for the amount of "
7 H. s+ i9 a' c( I* e& {6 Z. f                       "road.  Either increase the amount of roads "
. u' y! H! ]+ H: b                       "by increasing the GRID-SIZE-X or ". }0 ^9 {* j5 v" v4 c7 ?4 ^
                       "GRID-SIZE-Y sliders, or decrease the "3 m( t' u5 P7 h5 g' [' e: h
                       "number of cars by lowering the NUMBER slider.\n", Y) K: k6 J3 @
                       "The setup has stopped.")
" p( W" x, k7 a, X. ]& s& h! N( ]    stop1 N6 |) S) P& s) G1 }8 F4 Q& I- r  Z
  ]2 g1 r+ V" y" y! s2 n

1 _4 a1 K$ t- H$ d. t. i; m  ;; Now create the turtles and have each created turtle call the functions setup-cars and set-car-color
6 X8 s; o4 V, p3 c  crt num-cars' F" E( A8 i6 l; r
  [, }$ r% X, |$ f* ]
    setup-cars3 [) ]( W* i- Q7 |
    set-car-color
) w( Q( \( t3 X* ~    record-data
  {& x& @$ l8 }2 A, S2 {  ]' V( l7 d1 ^& {3 ^, D: d

1 d, x* N! @& \/ M  ;; give the turtles an initial speed& p: u3 F* b% h: t
  ask turtles [ set-car-speed ]
- X7 O. H) b4 \+ A( w! D# h/ R/ }6 c5 m' _; s
  reset-ticks2 l6 }/ l. p/ e/ q( K
end) G0 q- N, w( M

+ k0 @- o/ J5 o- `' q  b! g;; Initialize the global variables to appropriate values
' S* V0 i  c" t6 F5 h4 Bto setup-globals- C% L5 z. y* [% ~) E
  set current-light nobody ;; just for now, since there are no lights yet
3 S+ ?2 U& [  K7 c9 h9 E5 p$ u0 a  set phase 0
# k6 n* W- F2 [# H) [  set num-cars-stopped 0, [9 A% i6 y6 _) N9 A
  set grid-x-inc world-width / grid-size-x
! R& ]8 i# n# R+ f5 k- t  set grid-y-inc world-height / grid-size-y
. F4 J  \3 x- _4 l% r0 e  g, T: g$ w: p- [0 v3 @$ B6 M; a
  ;; don't make acceleration 0.1 since we could get a rounding error and end up on a patch boundary  D2 u6 s5 g6 d  M5 Z) R4 E
  set acceleration 0.099. q5 @) `; y4 h& B* j
end3 |/ f  O: h# d
; ^8 N# g# Q; ?" U8 S/ r2 A/ Y9 C
;; Make the patches have appropriate colors, set up the roads and intersections agentsets,
2 w3 Q9 d# z' Y8 f;; and initialize the traffic lights to one setting
% Y0 `" ~+ J+ E0 d) oto setup-patches
4 z2 w0 X2 S$ \9 r- J! v1 v  ;; initialize the patch-owned variables and color the patches to a base-color
  d6 |! Z$ s$ J5 |6 Z  ask patches: _- ?: [* W" v9 V& W0 N
  [7 M/ u+ I6 C6 f2 ^. \
    set intersection? false4 |2 O* _7 s) S
    set auto? false; S# x& Q0 [3 L1 e2 F8 L
    set green-light-up? true
* G) B$ G- ?& q. y    set my-row -1
! z% o6 s  C# s* m6 G    set my-column -1: v% k' q2 f1 Q4 d
    set my-phase -1$ H1 F" Q. D' ]" i( p
    set pcolor brown + 3: _  f3 c" }; X
  ]
( j! q$ k  W8 {4 R5 N, C
- D6 H5 X9 C1 F0 ^4 q  ;; initialize the global variables that hold patch agentsets
+ Y0 @/ O" Y! }( t  set roads patches with: B0 K2 r  S6 E
    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) or
* l1 |' X0 Q  u1 b  J6 n5 g    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]
+ [) Y+ L4 V& Y2 g  set intersections roads with7 Y2 W3 B$ C* ~/ B* S
    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) and
3 a: `# c5 h) A. j    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]
: p- n0 s& Z0 D2 Y" ~
& @7 y' z2 b2 t3 c" N1 G  ask roads [ set pcolor white ]
, X  P. I( O9 _    setup-intersections6 m& K0 R( `* K$ d" m
end2 u7 w1 X5 r& Y# y+ D% b
其中定义道路的句子,如下所示,是什么意思啊?+ H8 D3 n0 d0 I
set roads patches with  ~' L. F$ {# a# t8 w: _5 _9 C
    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) or2 r: @1 C! ?. K2 p0 v
    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]
% n: j& ~' F% D9 h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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