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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。# f# _  E( P# k
netlogo自带的social science--traffic grid这一例子当中,; L3 L7 b( ?5 J$ [' D: u! ~, w
globals/ \/ r; a  p# T/ j; A  t8 Q9 ~5 e
[( {- c1 u: i/ F
  grid-x-inc               ;; the amount of patches in between two roads in the x direction
5 w. Z" R* f$ V8 K0 R# V9 n  grid-y-inc               ;; the amount of patches in between two roads in the y direction
( w) r' A% n+ [  z3 [  acceleration             ;; the constant that controls how much a car speeds up or slows down by if) q8 {2 O" `& S( z4 x& ^
                           ;; it is to accelerate or decelerate
# S2 B2 o' }2 X$ A  phase                    ;; keeps track of the phase
/ ?9 g5 _( h% D" G2 i' L$ z4 Q5 ~  num-cars-stopped         ;; the number of cars that are stopped during a single pass thru the go procedure" R5 R/ z: O+ r/ b6 P9 H9 i
  current-light            ;; the currently selected light& I0 v+ t" {2 [+ p5 h3 h- p4 f

# i0 u! _8 @0 h! ^* j  ;; patch agentsets; o$ ]+ w2 ?8 S, t3 x& J# X- S& e
  intersections ;; agentset containing the patches that are intersections
# Y' h  e7 w; \* Y1 u* w  |8 L7 O: S  roads         ;; agentset containing the patches that are roads8 o5 s7 i* D2 e! |1 p
]
( u5 g  _* L% L$ {6 T! U0 N6 ^% ?0 i
turtles-own
2 g( R, X) Q1 r& }: b/ l: E[
, s; C# P9 ^4 Y3 A4 x/ t- _  speed     ;; the speed of the turtle( ~1 i! E% N8 r+ p/ _
  up-car?   ;; true if the turtle moves downwards and false if it moves to the right
. N% B' b, G7 v- w  wait-time ;; the amount of time since the last time a turtle has moved; a* Z. a+ p& O, J* m
]8 f, R0 t; T  y4 m* B5 f" I

# h- D3 z6 k6 ^patches-own
/ X  L6 {" X6 {) c[4 e7 t% X: o& p+ ?
  intersection?   ;; true if the patch is at the intersection of two roads9 j  `( d/ k. z) c3 \0 S
  green-light-up? ;; true if the green light is above the intersection.  otherwise, false.( D7 G* a6 \: z4 [7 e
                  ;; false for a non-intersection patches.
1 S* w% N5 I; B" _% O( N& K% `  my-row          ;; the row of the intersection counting from the upper left corner of the) A- s8 R+ ]7 q5 N9 K
                  ;; world.  -1 for non-intersection patches.. W2 W2 @; J+ @& J
  my-column       ;; the column of the intersection counting from the upper left corner of the
0 g- @+ h1 |: y$ \0 B6 {) K                  ;; world.  -1 for non-intersection patches.
* _4 D4 h1 z; O: K: r5 Q  my-phase        ;; the phase for the intersection.  -1 for non-intersection patches.
% K9 V6 t& Z' \, W7 U. w% `- F$ B  auto?           ;; whether or not this intersection will switch automatically.8 \% x5 I2 G* g. b
                  ;; false for non-intersection patches.5 ?$ C/ w  K$ j% h* B: s7 f! K
]! ~9 @, z2 ~  g9 ?5 V, F
; A$ d3 l. {" A/ y$ d+ S2 G' `
, e$ x7 ~; @/ N" t# I
;;;;;;;;;;;;;;;;;;;;;;; A3 p0 H! A" C9 J+ Z. X' v0 g
;; Setup Procedures ;;
* g; V8 `8 i2 F% @% F4 g;;;;;;;;;;;;;;;;;;;;;;3 y7 F1 F. Y5 i! _, K
8 m, D8 `& x- w4 t' i
;; Initialize the display by giving the global and patch variables initial values.1 v2 S5 J* U& }# X1 Q
;; Create num-cars of turtles if there are enough road patches for one turtle to. T5 ~4 u! F. N# j' B3 M
;; be created per road patch. Set up the plots.3 [, H$ g* u- G) `( _
to setup
% l+ e5 [2 E# m' U2 b- ~  ca1 b* g+ l# K  ^4 [" e1 m; J; ?
  setup-globals
! H' h2 |- z% q9 n" g* G+ Q
* R$ }8 Q5 ~* e+ T5 i2 ^% O  ;; First we ask the patches to draw themselves and set up a few variables# b1 o9 |  y: l4 U
  setup-patches. j* g' c  \9 u8 V6 B
  make-current one-of intersections3 k% _" b7 O# \7 n1 j! g0 B& [
  label-current" {7 o- _* Z: a3 C& ]
) I: o# `( D6 T$ {
  set-default-shape turtles "car"3 A8 v' I7 u% j% X
& ^0 x1 A5 z4 K% `% R/ K
  if (num-cars > count roads)3 `, {2 g: F; c3 X. Q  d
  [
* u/ a/ c1 s! H) B  |: l3 m    user-message (word "There are too many cars for the amount of "
) R" a: S1 C9 K                       "road.  Either increase the amount of roads "
4 \4 w( d$ e( e7 k$ b0 P4 W* Q                       "by increasing the GRID-SIZE-X or "  J6 {# n! l5 N9 t3 c, c- \( N
                       "GRID-SIZE-Y sliders, or decrease the "; z- Y8 n$ C# ?. c( B; h5 _* f
                       "number of cars by lowering the NUMBER slider.\n"* A( a) q  `( y1 d: ^# F+ U
                       "The setup has stopped.")8 b: S, [0 l4 D2 C2 H8 u& s
    stop9 }! P' s0 q# u1 D0 T4 \7 @
  ]0 g) G* k; o/ [6 Q5 N& A! W' C
3 v! `. ^7 }& y1 d
  ;; Now create the turtles and have each created turtle call the functions setup-cars and set-car-color" E/ e0 L- t% P$ x0 P
  crt num-cars& W; Y/ p: c6 ~- K" [
  [3 r9 b% M1 A  v8 h" j
    setup-cars( z3 b. c. ]2 @# `, w- U: i  u; A
    set-car-color
6 y8 Y/ t( t7 I2 m    record-data
3 \# r4 ^  I! ^2 \2 M' X  ]
, q. a( B, c* @3 K* ~% S; H8 x% G( D9 _0 F
  ;; give the turtles an initial speed# Q* B7 y- E  Y9 I
  ask turtles [ set-car-speed ], g1 f. J+ x1 u; @+ `0 O
4 c2 s& Z9 N: m( k; s+ B
  reset-ticks
) d# Y0 y# f! X: V& Tend
% r6 g5 V8 t& m! T5 L$ m8 V" o; r- X* m
;; Initialize the global variables to appropriate values
. Y; m  |6 i5 g3 K5 Jto setup-globals: q) n  \# e3 z5 ~) [+ X
  set current-light nobody ;; just for now, since there are no lights yet
% w  F9 K$ j# p$ K' ~! m  set phase 0
- x. n2 H" l2 c: \6 I; z. K/ O  set num-cars-stopped 0/ n% d9 A0 m6 B3 B7 y5 t4 V
  set grid-x-inc world-width / grid-size-x
  G( a" k& }, T2 S; L) C  set grid-y-inc world-height / grid-size-y
1 l$ q" _" Z( g$ V4 L! g! c7 y. k3 \* m% |. _
  ;; don't make acceleration 0.1 since we could get a rounding error and end up on a patch boundary
3 {4 H9 `' a; r6 H! Y/ I- P8 U$ X9 c  set acceleration 0.099* t6 [8 j6 ~9 B1 D' f0 H
end, k/ ^% o' ^8 M" o# A
0 [& i# ?! A5 B! k& @, N/ }
;; Make the patches have appropriate colors, set up the roads and intersections agentsets,
9 b" X6 u! D4 V* D% a;; and initialize the traffic lights to one setting
$ d5 }+ B9 Y- a7 k; ?5 U/ hto setup-patches
# S- S% Z1 G9 P. x( k  ;; initialize the patch-owned variables and color the patches to a base-color+ L8 x, K6 M' @  O2 V, E
  ask patches
2 m5 D% N2 H+ V3 y& E1 p  [0 S6 s5 u- U! ]- D: S- _) E
    set intersection? false
6 F- ~- O& n+ E. x% h- K    set auto? false, t+ [' N) T5 s" T& z0 K
    set green-light-up? true* a) _' F/ w& M: U) o
    set my-row -1* t- `  n$ m3 M6 |
    set my-column -17 J, I7 J) Q4 i% ^- h# _; P
    set my-phase -1" M) N( S5 Y' Z& ^! P
    set pcolor brown + 3: o6 T8 \7 Z, D' z+ ?
  ]
5 h& x$ l' G# R
; p$ y  R3 o- o. h! [, ~/ w  ;; initialize the global variables that hold patch agentsets2 H; d8 \/ Q5 G- x% f$ u8 R
  set roads patches with) b# i0 c/ s. h
    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) or! \* L; d& _2 r; Q1 O0 ~) I
    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]+ I# N) Y+ ~" B/ I9 J& K. ?
  set intersections roads with
  s/ L% K6 G  e8 {& z    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) and1 R7 B# W5 p" B" h4 _; ~
    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]# b! F9 D( F$ ~6 l$ t9 G, a

* ^  N$ Z. V6 q$ o# t# c  ask roads [ set pcolor white ]
: ?$ }( Q" ]# W4 W/ h    setup-intersections
" e  @4 s; z5 g7 Xend. U# S( S: [- G
其中定义道路的句子,如下所示,是什么意思啊?
) C4 L4 J3 n0 M! ?& m7 o( X1 d set roads patches with
# f, Q0 W* y- P5 \' `; r& I  k5 c/ p    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) or9 _' ~! U- u# j# O
    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]
4 T; v9 E' p1 i% C5 U2 g% ?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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