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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。% C" n/ X3 Q" U  C0 {2 h
netlogo自带的social science--traffic grid这一例子当中,
) a$ i% ~; P3 X. Zglobals
8 J2 D& `- O9 ?1 T0 C  x[: I" b! x% v2 ]& I
  grid-x-inc               ;; the amount of patches in between two roads in the x direction$ Q' x0 K% O* ~5 s1 g
  grid-y-inc               ;; the amount of patches in between two roads in the y direction8 `/ n" \4 D* L0 A+ W$ a
  acceleration             ;; the constant that controls how much a car speeds up or slows down by if
6 j! i8 d; i: i/ u1 C" d' d8 T                           ;; it is to accelerate or decelerate$ h' {' l/ p8 F( R! `6 G. C5 e) z  C
  phase                    ;; keeps track of the phase
* W2 l% u3 \4 B9 `$ b( x  num-cars-stopped         ;; the number of cars that are stopped during a single pass thru the go procedure
. o) V3 h2 M" D3 u  current-light            ;; the currently selected light
4 ]1 V% G+ i4 m" z) }) Q7 E& G* u8 @
  ;; patch agentsets* ?; N, g+ W/ j: `9 C5 X
  intersections ;; agentset containing the patches that are intersections
) a- ~' O2 g* I) B0 D  Z* h  roads         ;; agentset containing the patches that are roads
! A( L8 @- `7 M* e# N]
7 N. J* F7 b: r1 `" g, O- p, h% q6 C2 }  o8 }& W( u& O: y5 _
turtles-own% D; T9 b& ]7 E4 U9 G  J% E
[
& Q9 S8 N9 ^. A" V5 b/ S1 ~  speed     ;; the speed of the turtle$ }9 y$ t! z: @5 A& l
  up-car?   ;; true if the turtle moves downwards and false if it moves to the right7 H! e0 e& V. H5 w9 }# w6 Q
  wait-time ;; the amount of time since the last time a turtle has moved
- a' a3 U8 f/ p4 X$ c4 Y5 D]7 X% |* w6 C! g$ c9 Z2 |- i

* d7 m. \5 T) Y% T  }0 y7 y* zpatches-own
9 L8 X& [6 C( s2 o$ G1 v[4 x% {# I% ~' E/ ~$ E% M
  intersection?   ;; true if the patch is at the intersection of two roads
' k! q: x: h. R7 z* E+ D  W2 F4 g  green-light-up? ;; true if the green light is above the intersection.  otherwise, false.
8 b6 |; L" D1 V& l$ |8 t                  ;; false for a non-intersection patches.3 m/ i# t, S# F6 ^1 o7 n1 H, k
  my-row          ;; the row of the intersection counting from the upper left corner of the$ q8 I; f/ ?8 o' l  M
                  ;; world.  -1 for non-intersection patches.
8 J' |# X* s3 Y( I/ Z5 R* z  my-column       ;; the column of the intersection counting from the upper left corner of the
/ Z$ `2 [6 h$ j! X3 ]! e) W                  ;; world.  -1 for non-intersection patches.
7 ?+ U* I; J$ c/ G. _! ~5 _& @  my-phase        ;; the phase for the intersection.  -1 for non-intersection patches.
. V7 N5 P7 p  _  auto?           ;; whether or not this intersection will switch automatically.
5 {! n4 S$ K! e                  ;; false for non-intersection patches.
- [* d* A6 k& ]4 `6 G/ b]% Y' N3 ]& ]2 O  B- _0 z6 Q) O3 F

. `. H* p$ u! a5 M) L; v& i
8 I& e  T; [" ~;;;;;;;;;;;;;;;;;;;;;;& @( {( m- G" n. b/ H, z
;; Setup Procedures ;;
8 o6 {+ g+ C. x( c" M. D; o;;;;;;;;;;;;;;;;;;;;;;
, j/ V. p( H9 g3 p2 b0 O! @4 w# S7 t: T1 N2 ^( t4 }8 I
;; Initialize the display by giving the global and patch variables initial values.
2 E8 C' z! N) _; o;; Create num-cars of turtles if there are enough road patches for one turtle to* j, W& v. n0 Q2 o0 v- d4 X1 Z
;; be created per road patch. Set up the plots./ t& R( e. f$ ]* m* ^
to setup$ Z% r1 X5 Y/ z1 ?
  ca
; W1 \2 V! G' Q! K  setup-globals
- G. |8 M% U" ~% ~+ i  U! h1 h' H2 [6 F9 E; G% F
  ;; First we ask the patches to draw themselves and set up a few variables& Y. C: g4 |5 |6 n# M
  setup-patches1 S/ p. R0 R" b" q# C
  make-current one-of intersections
, z( S4 B& D9 _- m  label-current
) T$ d' ?! u& C, s2 U  z) h) _6 v) @2 X, Z# @& [# W3 N- k
  set-default-shape turtles "car"% r& U+ w  `7 l& b: H% {0 ^  A, b
2 Z% {/ ~3 _- E9 W7 x# F
  if (num-cars > count roads)
# ]3 O3 f: }, i6 [: r$ d7 h  [
- e7 N. C9 g3 v    user-message (word "There are too many cars for the amount of ", J6 }2 F6 p3 T/ `) O
                       "road.  Either increase the amount of roads "! ^( t. z# L" `
                       "by increasing the GRID-SIZE-X or "
% e! P( C! c( ^! I) p. _                       "GRID-SIZE-Y sliders, or decrease the "6 C1 S2 s. ^* c6 ]1 E) r2 d, q
                       "number of cars by lowering the NUMBER slider.\n": ]: y' c0 s1 I9 q
                       "The setup has stopped.")) u9 k3 z3 C2 i; n( s
    stop
( s6 E$ z1 V- M- l  ]
& {" J5 ^" D& {" v: c) W, p
8 |) L% v  X4 \5 ~6 h8 x0 X  ;; Now create the turtles and have each created turtle call the functions setup-cars and set-car-color
* I: h' S3 C: J5 g; Z  crt num-cars1 y; u% O& G$ T8 l- [+ U
  [* D" r- N! g9 D6 x1 r, S$ C
    setup-cars& @/ q3 w; x( [7 A
    set-car-color
* e$ d. P0 d: S% A2 f    record-data
0 r. ?/ d. [+ v  i1 Y3 h0 \5 I  ]6 G. A/ m$ ~% ~0 y' x

& \: v% e  A5 K3 X  ;; give the turtles an initial speed
& V; [0 }+ M* @- ^2 A  ask turtles [ set-car-speed ]
9 ~3 U2 {9 H$ S6 y4 K5 {+ r% U7 g
  reset-ticks. R; G0 ^4 h: D1 B
end' R* o4 o, Z9 U! Y7 S. o

% v  L5 k* \6 T2 e;; Initialize the global variables to appropriate values3 Y$ R4 T% o4 r- I
to setup-globals
" G5 x! v* l4 h  ]+ v5 @  set current-light nobody ;; just for now, since there are no lights yet
4 o- T2 q6 c/ K  set phase 0; x. X# i; F) ~: L
  set num-cars-stopped 0# k4 [2 ]; C  T: l$ Y% x
  set grid-x-inc world-width / grid-size-x
& R! n4 g: V, t+ p7 v1 g7 N) Y6 u2 Q) E  set grid-y-inc world-height / grid-size-y$ L$ ~( ]9 |4 {+ f: E; c( a6 O  \+ T

' ]3 r! R; r! W) U  ;; don't make acceleration 0.1 since we could get a rounding error and end up on a patch boundary1 I7 C9 }% h4 U& D* d3 J
  set acceleration 0.099
4 c5 K2 X8 F( ^" [end0 A. _, D9 c( o4 A* c
0 Y- X$ e8 ]  _$ l) z' ?
;; Make the patches have appropriate colors, set up the roads and intersections agentsets,
3 }3 C7 b+ E# n4 q1 r# D;; and initialize the traffic lights to one setting
- z% s; v6 g" w/ K) Oto setup-patches+ D& N# S: [' l. D3 d
  ;; initialize the patch-owned variables and color the patches to a base-color2 y2 D& k, U4 R, y3 k1 P' O
  ask patches
' Q0 W0 |, U& P: v! u1 B' n& F  [+ j+ D! B7 I/ l2 F
    set intersection? false9 Z3 v* C/ h- b! ~
    set auto? false! h& o5 ^/ I2 u
    set green-light-up? true8 @7 d' u: j. W1 R8 l( _
    set my-row -1+ k1 A$ m: e- |8 Y: l4 l, s
    set my-column -1
1 c! v! {( K6 h8 l' y    set my-phase -1
/ V6 J) V! n8 ?) n$ q! y    set pcolor brown + 3
3 P5 b1 d1 l4 _! S( a8 x6 C$ h# B  ]- {3 b) \: d) n; F$ f; C

$ k! w- B, m. L: [  ;; initialize the global variables that hold patch agentsets8 A0 T6 A& d! W& E$ i
  set roads patches with
1 U' O$ K: \5 q4 }7 F, K( G    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) or- {/ B. R6 X5 B& V" |# L5 J8 \
    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]& e' _  u% j" O1 g1 ~- ?2 D
  set intersections roads with
* l7 K/ S# [8 Y  @4 G1 X+ q9 z    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) and. p* A! V, c, A4 h
    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]
4 v5 I7 D9 e% S7 q  L: G
) w5 |3 \( P! c  ask roads [ set pcolor white ]0 ~+ z* `% W$ _& d" o
    setup-intersections
) V, v% ~; {5 M+ z1 d; P- C! hend
. m( c+ ?9 g  N# R/ p* F其中定义道路的句子,如下所示,是什么意思啊?
* t& R5 _" X' _9 ` set roads patches with3 W1 v2 r& u1 r. |
    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) or
( Q2 @" Q# L+ h$ _8 g    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]
& Y/ h& o# U- r* c5 }" Z& J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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