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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。5 q- L- B  f9 Y6 J% ~0 ~; O
netlogo自带的social science--traffic grid这一例子当中,
4 C& @  J9 ~3 d: E: X) t8 Oglobals
% e: p; \& n# L. h" L7 z7 g+ t[
* y6 O$ K- m! f( q" l# ~3 f: h  grid-x-inc               ;; the amount of patches in between two roads in the x direction% Q5 w2 l+ g( S2 E7 o0 y
  grid-y-inc               ;; the amount of patches in between two roads in the y direction
4 h( f" e( ?4 ^  acceleration             ;; the constant that controls how much a car speeds up or slows down by if
+ A0 R" [1 L! W( D$ c                           ;; it is to accelerate or decelerate2 E4 a4 u1 Q8 b( K  L6 K
  phase                    ;; keeps track of the phase- s. X) N3 |. Z+ W; j
  num-cars-stopped         ;; the number of cars that are stopped during a single pass thru the go procedure( ?! q" s/ J3 b# a3 L
  current-light            ;; the currently selected light; N1 i) G; U, t+ X' v6 q- T

$ z) \1 L1 g% X3 Z  ;; patch agentsets
  x3 h$ j' p( ~# R% L  intersections ;; agentset containing the patches that are intersections
$ [5 C- k: F) O  roads         ;; agentset containing the patches that are roads2 ?& C8 i! V5 P7 t* C/ o
]9 }' z0 w0 x) H$ @, U7 E; @

) \8 G5 V" u/ c, M% F* V3 ~2 B! Gturtles-own
% P0 o% @! E" L! c' v/ o+ ^[/ P7 u2 l3 [+ L) @
  speed     ;; the speed of the turtle; O8 W  V; J/ j& L( w
  up-car?   ;; true if the turtle moves downwards and false if it moves to the right
" a% Q3 U* c. V1 W  wait-time ;; the amount of time since the last time a turtle has moved
1 a- H% }8 l2 |4 N5 R: B% h]  u( a, b) B* x" M. o9 ^3 m$ G

2 e; D$ H( f0 J1 Vpatches-own
+ L' Q! X$ G# i* y. ~[- N  K: x6 d! u5 Z
  intersection?   ;; true if the patch is at the intersection of two roads
- Y/ u% E# i' v: G0 E  green-light-up? ;; true if the green light is above the intersection.  otherwise, false.3 q. Y! y4 H1 d6 {# m  @7 y
                  ;; false for a non-intersection patches.; ^2 X8 W$ X9 t0 b4 O% Z4 M
  my-row          ;; the row of the intersection counting from the upper left corner of the
+ ]# R5 ?1 r9 p( _" g0 O7 W- s  k                  ;; world.  -1 for non-intersection patches.
/ y; q$ j6 X& ~  my-column       ;; the column of the intersection counting from the upper left corner of the# F6 o* c2 `4 C9 }# A5 w" f
                  ;; world.  -1 for non-intersection patches." C1 }# y* ~( n6 U
  my-phase        ;; the phase for the intersection.  -1 for non-intersection patches.& x4 V- C8 w3 ~# {; D! z
  auto?           ;; whether or not this intersection will switch automatically.
5 o5 j- @& ~& p# V                  ;; false for non-intersection patches.
# M+ \/ B  p0 e- K, y. O/ S]
5 |9 M/ k8 R8 w0 a. [7 d
$ }4 q+ g& f; Z5 d9 O5 {
7 \9 {* g8 B; W# P3 ]" ^4 _;;;;;;;;;;;;;;;;;;;;;;
' J! T% X- `3 T' j; A0 h;; Setup Procedures ;;' J# P$ ?; N6 `2 g4 D
;;;;;;;;;;;;;;;;;;;;;;
: g# E: N/ _, H1 m7 Y% x! c* ]4 ~( M/ z) I1 Z- B
;; Initialize the display by giving the global and patch variables initial values.
( ~! s+ Q7 ?& P  U;; Create num-cars of turtles if there are enough road patches for one turtle to8 P8 I$ [2 I3 d
;; be created per road patch. Set up the plots.
, S, l$ P' H% g# Tto setup  a6 n2 X. H" k
  ca5 ^% f' q$ e7 g( k7 K' l
  setup-globals3 _. i4 v1 q+ e/ w( h3 H

# t: J* q7 |% F# Q7 o  ;; First we ask the patches to draw themselves and set up a few variables
4 f+ m* v0 x5 h* I( z  setup-patches: z6 c$ i# @+ }5 Y- I' q
  make-current one-of intersections
- z% a7 `  {" ]/ x9 e# T- Q  label-current
1 D: F, i/ p- s: `. n% W: f% ~% S: F
+ u8 O+ A: J4 m/ C- K  set-default-shape turtles "car"
: O4 e3 D6 a& \( S4 v4 Z" T# q7 g% k' O/ ?9 C) ~
  if (num-cars > count roads)( W# Z2 p$ `3 g7 W6 P" u0 |
  [
6 R8 A0 L: O! |+ w0 g    user-message (word "There are too many cars for the amount of "
5 _3 }+ w% {) T" b3 l( k0 y                       "road.  Either increase the amount of roads "
3 E  q5 n& a: u' P% g                       "by increasing the GRID-SIZE-X or ". o, ]8 S1 ]  }+ z
                       "GRID-SIZE-Y sliders, or decrease the "% I0 P7 A% @! {; G$ q% `) o/ [! d
                       "number of cars by lowering the NUMBER slider.\n". G% M0 x" b( ~0 W- y4 m
                       "The setup has stopped.")* b) y/ f" w* t- e: A8 b
    stop
$ W2 S; S8 N: p  ]
6 w1 b2 ~: c- q# U6 d7 M+ |* h
* A( g! N. s( I/ {  ;; Now create the turtles and have each created turtle call the functions setup-cars and set-car-color
5 `$ e+ p5 c& D" Q( C* o( S' v  crt num-cars
4 I7 K$ u: Z# V  [1 I2 V' n. j7 o. R5 m# K
    setup-cars4 W5 h: b2 _/ `/ p
    set-car-color
" D+ z' E/ r6 P, `# `    record-data
) C2 A- \5 m- ^' e. p5 ?' C3 W  ]# M) ~9 S( S9 g+ x
. @( F3 a; X/ ?7 u/ w+ w/ T
  ;; give the turtles an initial speed8 Z. G7 T" L/ x9 J. ]! T- \
  ask turtles [ set-car-speed ]% t7 L/ o5 B. \3 L

: N9 @' b3 g9 W- K  reset-ticks" T% ]5 ^" ]9 [' @# c( X
end
. l: }! |" ^* E0 N$ `
+ U* M# d* y; _- V; K. X; @5 C) e;; Initialize the global variables to appropriate values0 U1 G# O6 w& d" ^8 c6 g
to setup-globals
8 E; ~' ~+ U6 ~# }  n  set current-light nobody ;; just for now, since there are no lights yet& j% S, p  J6 d9 ]6 m
  set phase 0
: t, ]' f7 G# v+ _8 ?  set num-cars-stopped 0  ^& J, F. J0 h) e
  set grid-x-inc world-width / grid-size-x
+ A9 I8 X1 @1 j: M4 p$ z- E  set grid-y-inc world-height / grid-size-y# ~2 F1 a* Q: A1 \
9 w) {' P5 w  E8 [6 s5 M7 L5 Y
  ;; don't make acceleration 0.1 since we could get a rounding error and end up on a patch boundary3 v/ h: u' k* C( y
  set acceleration 0.099. e$ @' W7 ?5 c8 B4 X# t7 R' R
end$ r4 r, B* A1 R! H! c- G3 P
( a9 ]& A- |( f/ x. g
;; Make the patches have appropriate colors, set up the roads and intersections agentsets,
" E2 Z5 @6 R0 T* }9 [! X3 A;; and initialize the traffic lights to one setting; p' t6 O$ a! I3 s9 _
to setup-patches  _& c2 i* ^- ^% L
  ;; initialize the patch-owned variables and color the patches to a base-color
0 w& p5 y2 t7 o: Y) z/ C/ U  ask patches5 ]- U" e1 t0 v$ y& H
  [
( S$ d) z* K* V) e8 k    set intersection? false7 G1 [1 I9 X. @5 j, z% n3 @
    set auto? false
" k. m; O5 h5 ~' E. q    set green-light-up? true) W9 ~% G3 h/ w  p9 y
    set my-row -1& J* ~* P; d$ }7 [) i3 y6 v
    set my-column -14 R4 [' A7 ], G( T; Y
    set my-phase -1
; t& S. r/ g6 y! {/ V7 J    set pcolor brown + 3" G5 q$ K0 l# Y" A' N
  ]1 Q( _( g# D. O4 C

1 z- o7 B/ f: W' q5 E+ L  ;; initialize the global variables that hold patch agentsets( A: v# s! {6 a- P0 D
  set roads patches with( E+ R0 x, d4 a5 H  k  x
    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) or3 S' N6 }: N) P5 Z8 |
    (floor((pycor + max-pycor) mod grid-y-inc) = 0)], Z; G) K/ G% p: `6 ]% i
  set intersections roads with
4 g+ q; ^7 H. w6 [( a3 b7 U    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) and
/ F8 _  h" j5 T& O& S5 c    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]7 I) {( ], F; }7 T3 s
  e6 ^: R6 ^/ \
  ask roads [ set pcolor white ]
" \! L1 X  |+ f  }& ^7 o    setup-intersections
" y8 L2 X6 g: bend
4 Y! L" z; U6 d( `其中定义道路的句子,如下所示,是什么意思啊?$ z% |+ I+ Z8 ?5 H# b
set roads patches with
1 ?) y( s, r. q% t5 @- F    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) or
" d2 n5 \5 D7 d7 _, o    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]
8 Q- v' _& {) O' }( T. Z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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