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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。
( m& {- M6 ^' h) N0 Dnetlogo自带的social science--traffic grid这一例子当中,
) g+ j: I% K, m+ H5 E: ^- Mglobals
0 f5 P* E2 R: [[
  F5 a* ^6 v/ j- q& ]" j  grid-x-inc               ;; the amount of patches in between two roads in the x direction
+ h: {: y( }8 D! |/ A  grid-y-inc               ;; the amount of patches in between two roads in the y direction( x5 ~# |; @4 f5 F
  acceleration             ;; the constant that controls how much a car speeds up or slows down by if
0 ?0 I- n4 V; e& b$ _) l9 J. h                           ;; it is to accelerate or decelerate
8 Q; b2 \$ a6 |$ o- [  Q  phase                    ;; keeps track of the phase
, y( O. h* ~2 y8 l0 D  D  num-cars-stopped         ;; the number of cars that are stopped during a single pass thru the go procedure
4 ^# {% C7 R8 c$ ~7 J  current-light            ;; the currently selected light
0 C: O1 F+ P3 g& `1 j4 U  W8 }6 j1 _8 \
  ;; patch agentsets  i  @& Q3 `! @' k" [! d
  intersections ;; agentset containing the patches that are intersections
2 |5 f/ W$ m& o  J, {, u4 L0 _8 ~  roads         ;; agentset containing the patches that are roads
0 N$ b6 G6 c% b+ Y]
/ c2 F$ n2 |& D- ]' \' G8 Q0 Y$ d6 |" S5 W
turtles-own, W# p) s) [, F- `
[
9 e/ }& Q+ j4 m6 Z  speed     ;; the speed of the turtle4 Q* _* g1 t3 Y! Z& e6 N9 ~
  up-car?   ;; true if the turtle moves downwards and false if it moves to the right
$ G6 Z( O% I" w" Z& S3 m" G  wait-time ;; the amount of time since the last time a turtle has moved
/ A+ c/ a' F; O! s( ^. x, `& r]
/ O# g+ e/ o$ S1 X4 y: X
* l8 a( S7 J/ U. q2 wpatches-own
6 T; k( O$ Y/ M[
8 F: R! }) {) i0 i) p  H0 r  intersection?   ;; true if the patch is at the intersection of two roads$ n+ q7 R* r1 W. v% S# N
  green-light-up? ;; true if the green light is above the intersection.  otherwise, false.
% k, \# W$ W! q1 s" R, t' Z& @; c                  ;; false for a non-intersection patches.
' R( r: F1 h% ?6 I, q3 b: q" M  my-row          ;; the row of the intersection counting from the upper left corner of the
1 `* R! r) S$ b: _                  ;; world.  -1 for non-intersection patches.) m/ Y& ?- v" g
  my-column       ;; the column of the intersection counting from the upper left corner of the7 g8 Q/ \  o2 F5 B
                  ;; world.  -1 for non-intersection patches.
7 B8 t( u3 S& ~  my-phase        ;; the phase for the intersection.  -1 for non-intersection patches.: p& E* d8 w( g9 V2 G
  auto?           ;; whether or not this intersection will switch automatically./ \- G) e3 S0 B6 J' M4 h
                  ;; false for non-intersection patches.
- z  U& k/ K5 j! H. G/ I" e& J( g" {]9 _9 t  y4 R5 X% D" y: u
1 v: Q) Y6 K/ n5 C2 P8 B: h
$ A  M, D; @* P
;;;;;;;;;;;;;;;;;;;;;;# H6 x& w$ s% E  _
;; Setup Procedures ;;/ U: \" f( {- z1 e5 W
;;;;;;;;;;;;;;;;;;;;;;
& j  D% g6 j" d
! A# Y! y4 P; P5 ]* L% |6 [;; Initialize the display by giving the global and patch variables initial values.' }# w: H' x" y4 T
;; Create num-cars of turtles if there are enough road patches for one turtle to5 u- n0 a) L+ A* _( e: Q3 J
;; be created per road patch. Set up the plots.
* t+ k% Q7 U4 p9 }5 }5 O# ito setup
: K3 _9 m0 u2 Z5 B  ca
8 l! s2 g2 y6 C7 x8 R  setup-globals
, \: C, N/ o- z( U4 A' T' t5 H# ]0 u  A- l. B$ P- j
  ;; First we ask the patches to draw themselves and set up a few variables/ m5 H+ z, X2 r3 W9 S% c8 t
  setup-patches6 y* b- j4 B2 L: c( Y8 v& z, H! t
  make-current one-of intersections" N5 d  S3 H4 k- H" S
  label-current: \0 D3 ?5 Y/ V1 N2 @: V
5 K& D) [, v0 u& E& l, z
  set-default-shape turtles "car"" w8 l! @9 R0 h6 i& x- O
! n7 w4 v' y. g% N! W' _
  if (num-cars > count roads)1 t* Q; \' S9 i, i: J- @
  [& D2 s' M+ B6 j& j- S
    user-message (word "There are too many cars for the amount of "$ `* h6 p  ^0 k0 y
                       "road.  Either increase the amount of roads ". N& b' X9 Q4 v; Q
                       "by increasing the GRID-SIZE-X or "( h* q8 e8 G7 S) r" b% c0 F2 f& n
                       "GRID-SIZE-Y sliders, or decrease the "
6 Z* Z  V" u0 e+ g                       "number of cars by lowering the NUMBER slider.\n"; v' r- c& Y1 i$ \9 q# B3 [( N4 I8 S
                       "The setup has stopped.")2 f2 ]+ G0 j0 X+ E2 L5 `
    stop$ G' c) r+ N& i+ j
  ]
9 b  t8 q/ ^" {" P# m; J# e5 `8 s' ~2 C% ?/ ?5 R
  ;; Now create the turtles and have each created turtle call the functions setup-cars and set-car-color
9 p* [+ u, a. H  crt num-cars
  D, F( y: u# n. L: _9 m8 K( b  [7 X' ~, O$ C8 B5 c! r
    setup-cars
% R/ h! _4 i, F* e    set-car-color
5 G" I) C  Z/ a% s) [+ D3 z    record-data
; s9 S3 p. Z+ g3 c2 k  ]8 f$ h$ m3 t2 m; p* Z

$ j0 F- [4 x( V& G* I4 Y( [1 F  ;; give the turtles an initial speed
/ ^3 w- |) Q# `* E& C( X  ask turtles [ set-car-speed ]# f3 R& Q2 r6 P9 Y( z. C

1 G  N+ v+ }8 C  reset-ticks+ b7 y$ s( D5 k% D
end! N! U; O1 U) M9 k0 m! l
7 [# Z9 K; w' W2 V3 R8 D! C
;; Initialize the global variables to appropriate values
: k% N$ Q9 @; h, b4 B% _% J2 `to setup-globals
; b2 C1 J7 T2 p+ ?1 Z7 d- \* I/ w  set current-light nobody ;; just for now, since there are no lights yet( y! M2 Y4 ?" i1 ]4 ^9 I3 z
  set phase 07 g3 R& r" P# o
  set num-cars-stopped 07 Q+ T0 f9 A0 M- x: E
  set grid-x-inc world-width / grid-size-x
0 E. o! c' v$ h6 K4 j  set grid-y-inc world-height / grid-size-y
! l4 D: D; @4 A# s
. j' s( b2 Q$ B, \6 i: ^% x  ;; don't make acceleration 0.1 since we could get a rounding error and end up on a patch boundary
3 F9 p1 g  p3 Y0 Z; V  \. s  set acceleration 0.099, r+ m. q1 Z9 k; e  D- E
end
1 _, l2 X; j' j) _
, n# X4 [& b4 s! f( M;; Make the patches have appropriate colors, set up the roads and intersections agentsets,
+ N9 P" w+ t  J, y/ `. C: x6 P;; and initialize the traffic lights to one setting
* ^! K  M) C8 N2 C7 S* S0 |2 kto setup-patches
9 s/ x7 n$ Q5 m5 n+ D+ t  ;; initialize the patch-owned variables and color the patches to a base-color- Y( K9 G5 D' l* H  l6 k1 u( |
  ask patches
1 R1 V* P9 F+ ]/ o. Q  [. B- z% }. K$ c; T/ \1 W
    set intersection? false% f' ]; }4 G2 z' W: E
    set auto? false
' E% q# K' {; |7 t" E    set green-light-up? true
) L2 B1 K  O& A; `' H; x- O    set my-row -1; f8 k0 |0 j1 V7 u3 d
    set my-column -1) W1 M( C. N6 }& b  s8 _2 ?* T
    set my-phase -1- S% w/ C, c0 `
    set pcolor brown + 3! A1 D7 `: H6 g8 y" X3 @
  ]3 B& o* X. k" b; q6 K
' O  s9 z3 ^$ q6 d
  ;; initialize the global variables that hold patch agentsets" r$ U' w% g  H" Y+ e5 ~
  set roads patches with
( M$ h. O! F- B4 x; H    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) or
# E: h2 P; S6 I1 l/ h& o, D    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]
& O7 C5 e, X7 X) V+ [  set intersections roads with1 h; C+ ^: q8 L. Q5 D
    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) and5 \8 R" Z+ A$ J6 i
    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]. x9 I2 X4 y" b0 d
7 g% u7 o' V+ C+ L
  ask roads [ set pcolor white ]
/ ~* b. A$ g) r4 E' H& i    setup-intersections1 W% E* B6 c) N5 z
end6 K* ~1 H. Z* N3 ], e
其中定义道路的句子,如下所示,是什么意思啊?1 O/ O5 b7 [! ^+ y
set roads patches with
- ?! c- t; n- U1 @9 d/ {    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) or) `# j9 w7 ^" y3 a% s4 C+ A
    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]
& |- X5 K, f0 w/ K% 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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