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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 c# T8 @0 h' _6 g- b/ h
netlogo自带的social science--traffic grid这一例子当中,
0 [. m; \1 ^5 c: Oglobals8 g  H2 s2 _) o9 A3 G  F: \5 s
[
/ @& a( k& u8 p- V  grid-x-inc               ;; the amount of patches in between two roads in the x direction
, O3 B5 e+ x( [  grid-y-inc               ;; the amount of patches in between two roads in the y direction
0 ?( ^) Z1 m- P4 r! @  acceleration             ;; the constant that controls how much a car speeds up or slows down by if
1 F' w4 ?8 q: h0 z% p8 \3 V                           ;; it is to accelerate or decelerate5 N- F5 u9 [; l8 Q3 W
  phase                    ;; keeps track of the phase" H: Y# U; W6 T( T1 n' A
  num-cars-stopped         ;; the number of cars that are stopped during a single pass thru the go procedure
# ^3 g7 M4 [, D* H: R2 V/ ]  current-light            ;; the currently selected light  T: o- F3 T; D8 l  H0 H6 x6 ^: E
& U% n6 C3 \# s" y  N
  ;; patch agentsets- B0 _# E2 [( D3 F, S" a
  intersections ;; agentset containing the patches that are intersections; w$ G" I! u$ L" @
  roads         ;; agentset containing the patches that are roads0 g& m; ~- q: t5 l4 K8 w1 C
]
( P: a- W" y: y( |0 L7 X; d8 n0 Q3 s9 d6 F5 e$ W
turtles-own8 I) ?3 A5 u+ ^# P/ n! z+ r
[
7 J# C( ^8 `9 ~8 U5 t% e. ~: b  speed     ;; the speed of the turtle$ Q9 V3 |$ k4 A" O4 \- S: u
  up-car?   ;; true if the turtle moves downwards and false if it moves to the right8 d$ e" c0 K& X3 B2 ~+ n
  wait-time ;; the amount of time since the last time a turtle has moved4 G& J: b" u; ]% {
]
. [) f( w3 W9 `" b3 ]* S; b9 a/ U6 T: S: X. B9 r( T
patches-own
  z3 N9 X. z4 B$ c: S; B% R8 S[
5 M, x9 o% F7 }# ~* t* g  intersection?   ;; true if the patch is at the intersection of two roads
0 O+ n/ `5 }3 t# M; Z  green-light-up? ;; true if the green light is above the intersection.  otherwise, false." |. v' {2 Y# Q3 j
                  ;; false for a non-intersection patches.
- f  D' h& w0 G3 ^; T  my-row          ;; the row of the intersection counting from the upper left corner of the
3 d, c/ T2 U, v4 H. Q$ {& z0 Q4 s                  ;; world.  -1 for non-intersection patches.
6 O) u! P7 F; o' y" U/ W! ^  my-column       ;; the column of the intersection counting from the upper left corner of the
9 ?. E! g4 @' J8 s" t                  ;; world.  -1 for non-intersection patches.
1 E: t0 T) {1 O2 a, l' |& P5 z  my-phase        ;; the phase for the intersection.  -1 for non-intersection patches.: ]/ q2 X# Q$ I9 R
  auto?           ;; whether or not this intersection will switch automatically.6 j# Z: g( {4 D9 ~% p" e
                  ;; false for non-intersection patches.6 s6 U7 c, n) L/ i  Q9 \" k
]
% C1 z) w( Y* O- e, Z  c5 T7 n( |
+ R# f# \2 _5 s+ V. T- S5 `
/ U) }3 h* b5 h$ E7 `) i) @;;;;;;;;;;;;;;;;;;;;;;$ ^+ h; c2 u. W4 F, A
;; Setup Procedures ;;
0 j/ H6 F4 R3 d- X0 z' k;;;;;;;;;;;;;;;;;;;;;;& f/ x( v9 [/ j' F: o: h

: K+ q0 u3 t7 _, d5 s7 p# L;; Initialize the display by giving the global and patch variables initial values.0 p4 J. h' s$ u! N' K  K' b( h
;; Create num-cars of turtles if there are enough road patches for one turtle to
- u7 P( N0 w7 h6 V- [: G;; be created per road patch. Set up the plots.
  r/ x- n9 s: \to setup
$ G$ i/ H: i# g  ca8 s6 `, D: D5 V4 a5 Y, S  ?  h2 V
  setup-globals
/ Q5 `8 _) `2 Q1 l1 S1 y5 M- X6 e' B" I" u1 y  N& Z* E9 F
  ;; First we ask the patches to draw themselves and set up a few variables1 |* I: A" X3 B1 W6 r
  setup-patches
) H. m4 X$ q/ R" ~  make-current one-of intersections2 R" h6 q+ t6 A! u3 x& A
  label-current  P: h9 y) Q+ Q6 c1 S- [

6 K* W9 y( Q9 W7 u  set-default-shape turtles "car"
) m5 M3 H& m2 u. U- K1 o
, P1 G7 g. ^- _. i) N/ W  a! k  if (num-cars > count roads)6 ]# Y; X+ }, @9 [1 Q  e
  [
% y! Q+ m0 V  ]4 ^) {    user-message (word "There are too many cars for the amount of "( p6 \2 r$ v& C6 s6 |
                       "road.  Either increase the amount of roads ": l( r6 N- j9 _2 v* H
                       "by increasing the GRID-SIZE-X or "( h  v% c& q( L6 O; e  M6 U
                       "GRID-SIZE-Y sliders, or decrease the ": g( ~8 |: J' ]4 o/ M
                       "number of cars by lowering the NUMBER slider.\n"$ o- O  J5 A$ f9 H  t# q) l
                       "The setup has stopped.")
& w( s- c; O+ C. k4 D# V    stop
9 P" v, Q: `4 e; f% R$ `  ]
7 g. O, w8 L: Q7 w! v/ J# s1 j( x6 {9 \. n. f2 i
  ;; Now create the turtles and have each created turtle call the functions setup-cars and set-car-color
& x* h3 g* |/ C( J% Z3 G( O' V  crt num-cars& v/ J& p) t( d' N  M( J: b9 d
  [
) z( m6 O" m8 }% I# N    setup-cars
* x" m% e9 y- r+ ]4 o    set-car-color
# o. ~7 q3 C& ?- p$ j/ `% {9 U    record-data
" B/ X) A7 l4 G% n8 ?  ]
, u; _) L, T; }) p4 t- b
- Z4 N3 n" ~6 y) E9 a9 s- b  ;; give the turtles an initial speed5 N& X# W8 ]9 H' ^& P
  ask turtles [ set-car-speed ]( X+ B* o$ j* E9 Y! Q; O, y8 |

5 |& y3 s9 n( K+ }# X2 k  reset-ticks6 C6 |/ P: K7 ]8 L
end4 n5 `, Z2 u6 ^$ `) r5 ?7 a

+ o$ s8 D/ `3 w;; Initialize the global variables to appropriate values
$ \3 s) \' N& R# f, w, b+ d& Q' Oto setup-globals, u+ A5 W5 G! X& z' q3 m0 U) w
  set current-light nobody ;; just for now, since there are no lights yet
. k! R+ v5 B) _# ~; h  set phase 0
: C  k! B0 u2 d* y9 a# r  set num-cars-stopped 0
6 x- Y6 T( _8 R& G8 M. `. Y- a3 ~* E  set grid-x-inc world-width / grid-size-x
& R. ^4 o; ?& J0 `; ]  set grid-y-inc world-height / grid-size-y  z$ d$ w$ U& I& P

7 P4 H5 q- t& z" S' b  ;; don't make acceleration 0.1 since we could get a rounding error and end up on a patch boundary
4 P% Y8 @9 q) Z; h  set acceleration 0.0996 y% @; \9 @9 @8 z; k) d4 b$ k9 T
end, H" I% T9 x% o0 ]

. W$ n! Q0 g0 l  {/ B" K;; Make the patches have appropriate colors, set up the roads and intersections agentsets,5 {' [! n2 _* T: @( }" G. A9 ]
;; and initialize the traffic lights to one setting4 H" `6 ^+ ~$ w8 s
to setup-patches
& |% C- u- F% F+ y4 y: i! R9 y; `  ;; initialize the patch-owned variables and color the patches to a base-color3 P4 S/ [" }: i  U5 l
  ask patches% |( ]8 r) O# X, B* r9 W4 @( d: p
  [5 M8 @* e0 O- X" _  y5 {' i
    set intersection? false
7 y" }# o5 ]& E6 X/ O+ y0 W    set auto? false4 P7 J/ S# i# \2 Q$ f& ?, M2 A9 m
    set green-light-up? true
: Q8 i/ z: H' Y' P    set my-row -14 h8 F& _# [5 w# ~5 O6 Y
    set my-column -1. \) w4 t- v7 V7 c6 m* ^0 ?& A
    set my-phase -11 W9 `6 ?! u! F1 a( h* ]
    set pcolor brown + 3
, j$ r& [" Y6 q6 t( a' o  ]
; j( K8 h$ n2 W" J" \' }7 h3 q; n+ s
  ;; initialize the global variables that hold patch agentsets
# S( i$ L& v3 T' s3 d2 l  set roads patches with
' w! R7 D, X' ?5 P7 N$ L5 v% C    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) or7 y& X( G9 F5 H) O$ H. Y
    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]
8 A8 D' c+ a" I3 ~2 ~5 q+ [8 d  set intersections roads with
+ Q8 z- F* J% u# E- |    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) and1 ?& }5 e4 j: u1 A7 @. ]2 a+ Q2 B6 T
    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]4 D: G" |4 m$ b4 i" s4 G' W9 F: @+ X
) G6 t' O* ^* G
  ask roads [ set pcolor white ]
2 B4 B" w/ i4 V: I    setup-intersections
0 }/ y7 @( d6 W9 j5 f: fend
- r3 I( F4 R3 l1 {其中定义道路的句子,如下所示,是什么意思啊?' o/ Y- l/ u, r' w+ D( N( Q
set roads patches with
  o2 N, L$ K9 K: j    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) or
# ?" U$ J5 q2 Y+ j    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]
  n; p5 N% V7 [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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