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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。; x& v2 Q4 u7 F4 t  t
netlogo自带的social science--traffic grid这一例子当中,; G4 K# H8 [- i# B  l# o0 O/ M( _" r
globals/ e1 S$ i' s9 s. l0 `4 P! k8 ?7 {* b$ x
[
% {: v- q2 f5 _8 \( K( v# y  grid-x-inc               ;; the amount of patches in between two roads in the x direction
0 F% |5 G. U8 R  x" @  grid-y-inc               ;; the amount of patches in between two roads in the y direction. F) V! g6 ~1 \# |( R. A
  acceleration             ;; the constant that controls how much a car speeds up or slows down by if) T  @3 F6 S+ j% C1 w3 B  w8 W) Q
                           ;; it is to accelerate or decelerate+ m& I. h9 c0 u0 W+ s! B
  phase                    ;; keeps track of the phase1 P" I, @# l; ~8 f3 G
  num-cars-stopped         ;; the number of cars that are stopped during a single pass thru the go procedure
/ h, c1 `$ m7 l) P) D  W/ h# x  current-light            ;; the currently selected light0 f- i: C8 {1 W) a' c
$ e# {4 v& o* \: J% N9 g
  ;; patch agentsets6 M: _2 F% S  {4 p3 v& x9 F  Q( _" q$ D
  intersections ;; agentset containing the patches that are intersections* I) p, m+ ~' T, @
  roads         ;; agentset containing the patches that are roads
  y- V; N' i" _. {. d) H8 I]
7 h/ Z( w1 z# S  b
9 ^8 T8 z' R6 V+ h- R. k8 W! dturtles-own4 x# j! ]3 t- q/ L/ @& \
[9 k: G$ F3 X) ]6 V( u4 p  N& l
  speed     ;; the speed of the turtle' a  ^2 Y, o: L4 l
  up-car?   ;; true if the turtle moves downwards and false if it moves to the right" W* E4 c( u: B$ ]# [+ J6 V7 S% v
  wait-time ;; the amount of time since the last time a turtle has moved+ @, a  {" Z- q  J* W* R- |
]- H% Q8 R$ w5 |* b" }* z/ C: ^! Y

, m$ \- t  q& B4 D# s6 Q% kpatches-own
6 O4 E8 a! T- {, g5 e[
* T/ f' U0 i' |- d  intersection?   ;; true if the patch is at the intersection of two roads! i9 v% P+ I  N
  green-light-up? ;; true if the green light is above the intersection.  otherwise, false./ \0 F& ^, j2 M+ y/ Q+ ~
                  ;; false for a non-intersection patches.
7 K% C1 d  ^6 @" `- [  my-row          ;; the row of the intersection counting from the upper left corner of the4 O8 c: k* }- _5 u# v  A$ y; g
                  ;; world.  -1 for non-intersection patches.
7 r( e* Y. o: K/ p5 j7 C1 g- r  my-column       ;; the column of the intersection counting from the upper left corner of the
  s6 ?$ _9 e3 H  U                  ;; world.  -1 for non-intersection patches.6 C! I, A$ _8 \# t; j2 g8 q& i2 ^
  my-phase        ;; the phase for the intersection.  -1 for non-intersection patches.
( v& |6 _$ b0 R9 h3 b  auto?           ;; whether or not this intersection will switch automatically.
: O) X. P& I+ h* w0 x/ m1 B! M                  ;; false for non-intersection patches.
! V) ^5 f$ l5 I]; }/ a0 E- u, @5 Q
* `  c' r4 t' C) p8 O2 V
, B7 ^! a7 ~" o. s
;;;;;;;;;;;;;;;;;;;;;;
% Z6 k2 a) g- F. v;; Setup Procedures ;;) B# J" x4 ?+ V5 K( l( Y5 R! r/ Q
;;;;;;;;;;;;;;;;;;;;;;- z/ a! X" ]) U

0 S8 D, \5 o, A/ c6 _+ H;; Initialize the display by giving the global and patch variables initial values.. y3 H: _; p% O3 `+ F( R
;; Create num-cars of turtles if there are enough road patches for one turtle to4 q% O( [* ~# s, q1 p+ X
;; be created per road patch. Set up the plots.* t: W  }  n- w
to setup
7 O1 Q1 j* r! Q$ Y5 q7 B5 u" V  ca
6 ~* |) b3 b5 S* X; n! X$ p  setup-globals/ g' B1 y4 J; v1 Y
* \, W1 u8 `1 d* v
  ;; First we ask the patches to draw themselves and set up a few variables* @8 q& Y% o! C4 y6 O- |
  setup-patches9 T5 f% e& a2 J, A9 d
  make-current one-of intersections
6 V+ h; S3 U" }' D6 r- B  label-current
4 {  s9 [# E. {6 r6 u  W- _; [$ m- A9 N- S, l  s: }; m
  set-default-shape turtles "car"
2 w7 y! }0 H/ l4 J& t6 i
  Y, y/ h" R! ~/ n) ~  [" v  if (num-cars > count roads)2 m9 o1 C! B( }% l  P6 u9 m
  [
6 O% v* e% ?# P; t1 \& B    user-message (word "There are too many cars for the amount of "
/ j. e. B6 }& e2 c                       "road.  Either increase the amount of roads "
! \% T8 A# d, X# T                       "by increasing the GRID-SIZE-X or "
+ `, {6 y: Q5 X  m0 X                       "GRID-SIZE-Y sliders, or decrease the "
# p7 Q  A+ j$ U; H% A$ y  P                       "number of cars by lowering the NUMBER slider.\n"" w1 X8 F* E: [1 r1 K0 V
                       "The setup has stopped.")
2 `! x  m  x5 W* m8 ]) V! N    stop" r* S& w) p$ @! ]& H' {
  ]/ W' _2 V* w- b' e
, t7 Q- K0 ~! x9 j
  ;; Now create the turtles and have each created turtle call the functions setup-cars and set-car-color# e4 d+ B$ c- A" {2 P! S8 k
  crt num-cars
: f( e- r* Y5 {! f) O% T- O  [
+ e* F- n, w/ r5 Y. Z$ [6 |9 I! D    setup-cars/ m0 S! a! B$ _. g" B8 Z/ ^1 M
    set-car-color* b# ]  H5 |8 }, x
    record-data
+ v9 r, A+ I8 |7 l( H  ]" W4 ~" a9 d4 v" I2 }, K

' W7 p/ L7 L" ^5 `+ ?5 S  ;; give the turtles an initial speed
% k! p8 J5 C* c5 `3 b  ask turtles [ set-car-speed ]- @- m3 b+ S, d# m2 C& k, z
( b) ?9 E* ?9 X# ?/ I1 b+ x! [$ L
  reset-ticks
! l, ^' l# _; @3 A: V/ Jend
7 Z2 |7 Y2 ?% r9 z: I: C/ _
$ q) d) V; p0 S% n2 E4 R% i;; Initialize the global variables to appropriate values+ H9 _+ c$ s: y0 |  F
to setup-globals
1 @5 K, n4 v- x: d  set current-light nobody ;; just for now, since there are no lights yet
* R7 W, h4 q: F4 U# T  set phase 01 g- a% K- M' r# Y
  set num-cars-stopped 0( w" \- Z* _, m
  set grid-x-inc world-width / grid-size-x
6 z. K) \  d% R( F8 O% G  set grid-y-inc world-height / grid-size-y7 |3 z% d; z+ s/ p) o

1 j+ T; z& t% K" a' E2 K  ;; don't make acceleration 0.1 since we could get a rounding error and end up on a patch boundary
% L4 l/ Q+ c4 V1 O# e9 k) y1 u  set acceleration 0.0991 U* }4 z& h) X
end$ R, o4 j' [/ Q! b2 U
, L; J& m) F* C( D5 k
;; Make the patches have appropriate colors, set up the roads and intersections agentsets,% k2 k) @  L: |, k) f4 A" B  K
;; and initialize the traffic lights to one setting
9 J: E+ _+ m0 k% }# tto setup-patches
- K& B8 B, ~" {) u+ g( J  ;; initialize the patch-owned variables and color the patches to a base-color
5 a6 s. ~  E" Y, P; S6 ~  ask patches+ f- H0 e9 M: l9 V# p6 v
  [" P' ]& N3 w  A1 s
    set intersection? false
# q: \& C; S5 Q7 u. a3 i    set auto? false9 O3 `6 T* s' A' m' a% O) [
    set green-light-up? true
6 }) I, ?2 |" g    set my-row -1& W0 t% w& d5 t" \; K+ T/ f/ {
    set my-column -1
% I; b7 G5 k# N7 }- }    set my-phase -1$ T1 A  v4 S4 \2 T. L
    set pcolor brown + 3
2 R6 ~( _$ [: ~, X  ]& x% j; O9 V1 ^& P# \5 I

6 b  u7 i# }  C6 q2 r  ?  ;; initialize the global variables that hold patch agentsets$ {* Z" b3 _: L+ c- B7 e+ B, C! h
  set roads patches with, _- Q7 r1 s" y% ?7 }9 u
    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) or9 v2 C0 Y( M/ B2 t) S* ~1 q# B' e6 [
    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]
+ z& D) Z* W7 L" f* ?  set intersections roads with
% ?! U/ B. K5 N9 ~4 ?) F    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) and
! w# p# j7 c" M* m2 `+ j    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]
. c# n; }* \0 G& w% i4 }' c" E+ p% D7 S. f
  ask roads [ set pcolor white ]
* r( v" y4 c+ V    setup-intersections
, w7 ?) m  {( S$ Q8 Lend
% D, U# f" ~. @其中定义道路的句子,如下所示,是什么意思啊?4 ^# q- V  X7 Y" X1 N
set roads patches with. o; ~7 _/ U2 _1 }) E
    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) or: p8 L+ H: s2 d$ T: i" @
    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]
, {2 g1 i2 [  q3 X3 @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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