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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。9 ~" [8 H: V3 R8 d% g2 a# r% _
netlogo自带的social science--traffic grid这一例子当中,/ U; ^) ~8 B0 |7 e2 n- w
globals
7 `/ [: j# m* A( {* F5 b" o  E* l0 K[; @* h  K9 C& }! L7 ]- t/ [
  grid-x-inc               ;; the amount of patches in between two roads in the x direction
) @9 d* j+ a, I; |# l- A8 `  grid-y-inc               ;; the amount of patches in between two roads in the y direction
# v( U4 @; i: H! k  acceleration             ;; the constant that controls how much a car speeds up or slows down by if9 x9 @; X& N" `9 I; d
                           ;; it is to accelerate or decelerate) R) {1 Z* T  @# @2 i
  phase                    ;; keeps track of the phase) o& ]( q3 P, `# I  M
  num-cars-stopped         ;; the number of cars that are stopped during a single pass thru the go procedure6 {/ M" j& {9 E: B# A# L
  current-light            ;; the currently selected light" \# d0 `6 @( c6 B! m
$ \( h8 ?% b6 L4 y2 u6 m
  ;; patch agentsets
6 k; j, v3 n# z0 }& A  intersections ;; agentset containing the patches that are intersections
' t- r7 d- p0 p) ?" g' T* \2 ^1 H  roads         ;; agentset containing the patches that are roads2 L) Z8 m! O4 n1 z7 y0 s
]2 E' k, e4 V% p, R

1 f* t+ j: `! E+ vturtles-own9 c' `* e  S  b
[
( ]2 }3 z+ Z' I* q  speed     ;; the speed of the turtle/ M! o7 U. D% g+ C0 R# n7 x
  up-car?   ;; true if the turtle moves downwards and false if it moves to the right
6 ?1 L: Q" [3 X. _2 x8 a  wait-time ;; the amount of time since the last time a turtle has moved3 E$ N6 X, f. R& e+ s1 M
]
+ O+ i0 S% ]2 |1 G' M' ]4 O5 m( ]8 b% E- B! t
patches-own+ m3 K; S* H+ f8 x. k' [8 a9 D
[6 X; q" o: O: t6 ~
  intersection?   ;; true if the patch is at the intersection of two roads
5 ?/ P+ n4 L5 i$ T- p$ P' c/ S  green-light-up? ;; true if the green light is above the intersection.  otherwise, false.3 H9 j) u& ^5 k. w
                  ;; false for a non-intersection patches.
, Z0 |* Q! Z! E" A- f! [  my-row          ;; the row of the intersection counting from the upper left corner of the
1 U; F" ~2 ~- W6 u                  ;; world.  -1 for non-intersection patches., k0 H4 W7 t9 F! u, _* o
  my-column       ;; the column of the intersection counting from the upper left corner of the+ I1 D: [7 z/ t* D/ l3 k5 K
                  ;; world.  -1 for non-intersection patches.
% z1 z4 y0 U+ F  my-phase        ;; the phase for the intersection.  -1 for non-intersection patches.7 x9 ~& \+ {# s4 S- Y. M
  auto?           ;; whether or not this intersection will switch automatically.
5 E5 C' [1 k: x; b4 @                  ;; false for non-intersection patches.
. ~/ B4 R1 j1 M]
  H% G- j/ ^( J) Q. |
3 n5 K3 v. A+ _3 i( T  s: w0 ^6 W2 S" I6 O0 ~( A3 i/ v6 O
;;;;;;;;;;;;;;;;;;;;;;
, R9 g+ B$ X3 V' H; M;; Setup Procedures ;;% P/ Z# V% R" \6 Q# H
;;;;;;;;;;;;;;;;;;;;;;% @7 Q$ o. Z+ ~3 y  K- E- i# V; V

2 j9 Y  Z' N, C3 m$ P6 w1 A$ |;; Initialize the display by giving the global and patch variables initial values.
: }8 |8 j1 ]* ];; Create num-cars of turtles if there are enough road patches for one turtle to' ^: d) Y6 S$ V' a/ {% u4 M/ D: O
;; be created per road patch. Set up the plots.$ R+ X1 V4 b7 _# ?
to setup1 N: c1 q5 n  _  K
  ca! m- X: R3 D; Z) w* Q
  setup-globals) y: S5 T( g8 e6 ~' y3 k! Y; d

0 `& D: E7 u1 h6 z- E& s7 H  ;; First we ask the patches to draw themselves and set up a few variables
/ v# \, X4 k4 I7 H* C, s  setup-patches3 Y* z- K  w! H5 B" B5 M
  make-current one-of intersections
7 X: _3 Z( y$ ~% l( n- h' K  label-current7 C7 Q- {+ ]4 E0 V
6 U. m) Y  }/ w& y2 u
  set-default-shape turtles "car"
) }* o7 y" t6 f$ m4 E' b9 c8 \7 e/ I
  if (num-cars > count roads)
, ^% E- z2 V0 H, S0 x( N  [
$ U7 n3 R, k* P( y5 o    user-message (word "There are too many cars for the amount of ": B& j! M2 ?0 _8 y3 L! d
                       "road.  Either increase the amount of roads "
0 o, T: ?8 M+ v& r                       "by increasing the GRID-SIZE-X or ": _! ~+ V: p: H# |& A1 W* B
                       "GRID-SIZE-Y sliders, or decrease the ", S' Q6 t" U. k8 m
                       "number of cars by lowering the NUMBER slider.\n"
6 X4 u5 s" n6 s% D3 I                       "The setup has stopped.")
% V3 W( r# u0 N    stop- ~  s* O! h3 \) i
  ]
  U; C; G  E# S5 t" f  Z, b
- L! s+ q1 T; K  U. o9 {7 _8 D  ;; Now create the turtles and have each created turtle call the functions setup-cars and set-car-color, s8 q2 T1 f- Y" a, K
  crt num-cars% T1 d) g' d7 J% q
  [
  k/ z% w& _& Y& b' Y% \    setup-cars
( O* h: u) e6 Z1 A& E    set-car-color
% t  |3 ]/ G; S3 b# D    record-data  T5 J& i4 C0 ]- h
  ]
1 D- E  u% l6 j/ ]9 E% L# h: s5 m- U" s# U; V; n: D
  ;; give the turtles an initial speed
9 f- q9 k4 a( o  z  ask turtles [ set-car-speed ]
: Z8 X6 W9 w3 H% S# W2 c$ w' K; x5 @0 t
  reset-ticks* x) \, H# t3 X! y3 T1 \
end5 W8 i9 W' C9 k+ z* S  `+ }, V1 ?( e4 P
/ j0 x: a. V$ h, |% b% C2 H' i
;; Initialize the global variables to appropriate values! t3 w' e% \; s3 b+ J5 H/ e) |
to setup-globals
6 t. N! D$ ]4 N4 t# J  set current-light nobody ;; just for now, since there are no lights yet
# H" }6 w: l% o5 D  g% W  set phase 0
0 B# [* M& B6 a& L" \3 |# g6 i  set num-cars-stopped 0
* f6 g6 y4 d. w- r  set grid-x-inc world-width / grid-size-x
7 S; y7 n% z. }- U3 @2 C3 m  set grid-y-inc world-height / grid-size-y  I1 ?, G  z, @$ U

  r9 Q% {  b$ r( e9 n( y  ;; don't make acceleration 0.1 since we could get a rounding error and end up on a patch boundary
+ ^) a, r; V0 O7 q( k7 o6 E- n  set acceleration 0.099# Z3 q) ]' W+ u
end/ Y0 g; F+ B9 {0 m9 g
6 n0 c" Z8 g2 B) j- R: |$ P! A/ z
;; Make the patches have appropriate colors, set up the roads and intersections agentsets,# g1 b& ?, _* A7 Z
;; and initialize the traffic lights to one setting9 G$ t2 Z0 k1 }1 D8 ]
to setup-patches2 `. w5 ?* w" A$ r) n
  ;; initialize the patch-owned variables and color the patches to a base-color. f3 v) }/ h- A% U7 Q0 V. j0 K
  ask patches
0 V  b3 U* D! W3 m  [
  F( i. e. l3 d    set intersection? false2 Z% w9 n2 X6 T- Q( J
    set auto? false
8 w3 g& n  \7 R* ]( P& ]9 H    set green-light-up? true
# p  o2 d+ M3 Q" `    set my-row -1
  ~$ |/ A, w& D' ]5 ]    set my-column -1
! G& ^0 U' \8 O3 E- Z' b- o* P    set my-phase -1! o: f: q7 p; r# K& y
    set pcolor brown + 3
8 T6 C- N. ^; x4 }& @. _  ]1 K# t1 J) f6 X& K3 B( J/ ]
% x5 P4 u  F$ C6 R' n1 E+ Q$ F+ d
  ;; initialize the global variables that hold patch agentsets9 |6 {  c& g/ T  Z6 |7 s7 G
  set roads patches with
, G! B! ]" T) E7 ~4 C  Z8 o9 r+ ]    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) or
& q/ V; l, _9 _# Q( G! b    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]
4 p% Y5 J  z7 X! L8 P  H" b$ W  set intersections roads with
+ R' s$ D0 N3 a. Y; l9 m+ E    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) and
9 p0 F3 ~6 d, x    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]6 h) ~5 G% \" h' s
5 Y1 n  Z  C( a& A
  ask roads [ set pcolor white ]+ N2 }# ]4 x8 z" F
    setup-intersections8 b8 F& u. C, J' }8 |
end
) T) m* {3 U  ]+ E# w4 @其中定义道路的句子,如下所示,是什么意思啊?
# _9 D- T9 G& Y3 A- a* O set roads patches with
- J- E8 I9 m9 u+ q8 w$ n    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) or5 n6 V; R4 g. `* Q, \; _0 {/ n
    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]
* r; u  J/ K, s, q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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