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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。
+ O* t0 f# Z' c8 S. I# h6 |2 _netlogo自带的social science--traffic grid这一例子当中,8 O9 w: X& K' H, U9 X" o
globals: f5 J7 W$ K" c% u, @( c! I( k
[) A$ Z9 f* `, }" C+ L! R% \) T0 C2 }
  grid-x-inc               ;; the amount of patches in between two roads in the x direction
1 _. M0 ^1 \4 e9 J  Z# k+ ^  grid-y-inc               ;; the amount of patches in between two roads in the y direction
$ F$ `+ S# ~! |  acceleration             ;; the constant that controls how much a car speeds up or slows down by if1 u' h, Z: b4 ^- N% s
                           ;; it is to accelerate or decelerate  m4 O! ~4 C* {' N
  phase                    ;; keeps track of the phase
) C  ^" e" P* i2 z) \' A  num-cars-stopped         ;; the number of cars that are stopped during a single pass thru the go procedure
1 d3 X0 q( R  o9 P; B: t  current-light            ;; the currently selected light
  N$ Y' G2 D) R' M' u$ D
( T$ |( \& e  ?3 Y. d. @0 b0 H  ;; patch agentsets
& ]7 B& U. K& [& @  intersections ;; agentset containing the patches that are intersections
: Z5 H. M, ]# C5 M0 e  roads         ;; agentset containing the patches that are roads
; N$ l6 V  d2 u' E]! p& q  |3 L6 N6 m; V' ]1 ~9 ?
+ H, p2 N2 m$ t2 U
turtles-own3 `, g. ?8 [9 w7 q) x4 x% C
[6 v1 h* p2 ]/ U( j9 H/ p' `/ d
  speed     ;; the speed of the turtle( y) t. n+ n# S3 K7 y. G
  up-car?   ;; true if the turtle moves downwards and false if it moves to the right
3 M* a/ f' x9 {; o" Y' u& Y  wait-time ;; the amount of time since the last time a turtle has moved- m& Q3 }$ u0 b6 K' J. [! ^# Y2 r. N
]$ L8 S! o  L( a+ w: N8 `# d

5 n% D- v/ R4 \* X  zpatches-own
* ^" Y) S5 c% x" k5 u$ l, p6 f[% m9 q5 P. V- j$ f- g# n, F
  intersection?   ;; true if the patch is at the intersection of two roads5 D3 |; ~# @; V1 K8 V
  green-light-up? ;; true if the green light is above the intersection.  otherwise, false.% J5 y3 }+ M) X, H1 ]
                  ;; false for a non-intersection patches.3 b; X( P3 W5 T
  my-row          ;; the row of the intersection counting from the upper left corner of the9 s2 _. t3 _1 }! |$ M( a+ V
                  ;; world.  -1 for non-intersection patches.
6 A7 x+ q! j# c. {1 Z: T& c/ L# X  my-column       ;; the column of the intersection counting from the upper left corner of the6 N$ C! j1 [/ X( B( `1 l
                  ;; world.  -1 for non-intersection patches.
- M4 c' J/ a4 S# z3 `: \7 N  my-phase        ;; the phase for the intersection.  -1 for non-intersection patches.. k* B1 y& O9 I3 U8 j1 P% i
  auto?           ;; whether or not this intersection will switch automatically.8 Z3 W5 Q1 W  m
                  ;; false for non-intersection patches.
+ ^& E, d  O  e, c. B]7 O& {; X0 y% R+ o& `
/ v3 b! a( n! G3 Y

$ M" T* D, {% Z: {! F( T;;;;;;;;;;;;;;;;;;;;;;
; i. t0 ^/ o) |' C" L3 |- j;; Setup Procedures ;;1 B) z6 a* E9 ^6 k
;;;;;;;;;;;;;;;;;;;;;;
. ^: i( }+ W! ~% _7 j$ K  x: T! k2 w# ~$ E. s
;; Initialize the display by giving the global and patch variables initial values.4 d: X3 o; A" v& r
;; Create num-cars of turtles if there are enough road patches for one turtle to
: f' y0 C) t% |. M4 e;; be created per road patch. Set up the plots.
- [6 k. d% d) T3 k  A  sto setup+ v& x" ]; K. [) n) ]
  ca
9 o( h6 \7 @, S* b  setup-globals
' ^  |& R" w) {: _8 Y' s+ r* F
/ m; a  ]+ h, w! t# o  ;; First we ask the patches to draw themselves and set up a few variables
. V8 Y4 b* s* U  setup-patches# ?3 f, M; P* d8 N) _8 l
  make-current one-of intersections
8 t2 Z; ?, P, e9 n  label-current
/ }* T  W( K2 X
$ C- l0 ^# q4 f: b' n0 Z  set-default-shape turtles "car"* j# T) R! |5 O3 d# |
0 @2 D6 i1 X; B+ j4 {
  if (num-cars > count roads)% L) {' N; C  J% v/ A
  [  R% r7 S, N/ X
    user-message (word "There are too many cars for the amount of "8 |# s: u# c+ F0 }" Q4 D1 p+ E' A* A
                       "road.  Either increase the amount of roads "
$ G8 X8 h7 c* ^+ ]' A6 A% e  _1 }" _6 B                       "by increasing the GRID-SIZE-X or "
" a, z; `! a, T, r0 S                       "GRID-SIZE-Y sliders, or decrease the "/ d1 u9 b# D7 y) ]& P; R9 u7 S
                       "number of cars by lowering the NUMBER slider.\n"* M! o' \. p0 B6 n! n$ O( V
                       "The setup has stopped.")
: G+ M3 p$ i9 c1 d& H4 e    stop2 F7 @, {! w$ s. [5 p" Z" X
  ]
/ m" M% C' R+ w* J, L) U2 K/ n. o( x
% w3 }' m4 e& ~( B8 Q* o  ;; Now create the turtles and have each created turtle call the functions setup-cars and set-car-color
- \; ~, k8 D) }2 c' t  crt num-cars
3 h* K, v# _% \/ D( p, V9 u  [
- R2 g  L$ S- ~5 G    setup-cars1 s8 n7 X& P/ a; |. j2 [( @+ F
    set-car-color
$ g9 P" V/ c( T; [    record-data1 E1 y0 Y/ \. e# V. |
  ]
7 f7 `2 A$ `7 S# J9 H" t0 V  T* H  e) Y7 X& F2 k, K
  ;; give the turtles an initial speed
( N0 l: x$ H9 y, X) E  C  ask turtles [ set-car-speed ]3 p; j' w) {, E$ K- D2 s
+ H9 W- W% O) c4 J
  reset-ticks
, E7 o7 _) N( _1 Y- O3 Cend
8 d7 ^6 \" D- j  _' x
$ v+ f$ A" O0 L3 e;; Initialize the global variables to appropriate values2 o4 [% x$ s4 k; I
to setup-globals8 y+ Q' t0 j; l2 o- _( }9 @; w( U; Y
  set current-light nobody ;; just for now, since there are no lights yet
8 Z' h- P  c8 o; \  set phase 0
1 d$ W, f. s% P# [  set num-cars-stopped 0
& n( k& ]8 l+ H& |. i  set grid-x-inc world-width / grid-size-x
3 p- _9 c  R& Y" v. n% L7 h  G9 t  set grid-y-inc world-height / grid-size-y; _) M0 W5 V* s& Z# ~

% P8 r9 B2 m3 }& P  ;; don't make acceleration 0.1 since we could get a rounding error and end up on a patch boundary( y4 u$ Y/ b# U/ P8 ?  P6 W
  set acceleration 0.099
5 h9 l) A% k' V. wend
( v, ~4 P3 b% q$ }" ]  }! r; k" @  Q! o: i7 \" F$ p
;; Make the patches have appropriate colors, set up the roads and intersections agentsets,
$ C1 s7 e1 u- T+ Y+ G;; and initialize the traffic lights to one setting
" m# u7 W- c6 B& e! A: kto setup-patches
  h% I0 u  u! K" A; p; A  ;; initialize the patch-owned variables and color the patches to a base-color$ S' T- r$ k( B
  ask patches" b+ l# C5 W- x/ q! p
  [/ p  l% |3 F, w* o8 I* z
    set intersection? false
. m: J. X6 N2 I* {5 w% h1 l! D    set auto? false! a, k' w9 l. n  e9 @
    set green-light-up? true3 E/ z  n$ ?( J. a9 @
    set my-row -1$ k- \! N/ K# N7 G
    set my-column -1
5 n% k+ M6 x  z- r/ J$ [    set my-phase -1
9 [- Q# O% z/ {3 _4 b# \$ B    set pcolor brown + 3* t; H4 w. x6 H: M$ q
  ]
( {  j6 E: d$ n& w! _
2 P& K) I' C( a0 k  ;; initialize the global variables that hold patch agentsets2 [$ G6 K4 e. _% R
  set roads patches with# h# ~7 B- {2 d1 G. l0 w
    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) or
, a- u' \6 ?4 a7 p3 z    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]
& A9 c' k3 t; @+ g( s  set intersections roads with& N  k9 e" W3 {0 m; ?) K$ Y
    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) and; E9 |( u. D1 U. [
    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]
$ s5 Y/ `' v3 q: V" D
$ P$ k: e9 b* k* z# G/ M+ e! v  ask roads [ set pcolor white ]5 h& I8 H; f2 \& Y5 b
    setup-intersections
5 }8 G7 s1 B4 ]* ]5 @3 x5 eend: ]1 D8 L2 e4 y9 p
其中定义道路的句子,如下所示,是什么意思啊?3 B  d4 J# B  Y! w+ s
set roads patches with
9 I" n5 f9 z! y! P  i    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) or
/ K/ U7 V: u* }- V# P( s( q    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]& y- m) N/ V0 S5 q/ O$ K
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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