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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。, s$ C: U- w; L0 S; T& V1 H4 ^4 d1 }( H
netlogo自带的social science--traffic grid这一例子当中,
& [4 s' _3 k3 p; y: g7 aglobals
0 S8 q/ L; `+ J0 O8 F0 f3 @: Q[
9 t$ j) e, O: T  v. t4 v7 i  grid-x-inc               ;; the amount of patches in between two roads in the x direction
- J9 y' o7 t+ k+ D; `" Q  grid-y-inc               ;; the amount of patches in between two roads in the y direction
9 @+ X+ s% a9 F4 C! a: ^  acceleration             ;; the constant that controls how much a car speeds up or slows down by if
, u- u, l* p; n8 i2 H6 x$ P0 F                           ;; it is to accelerate or decelerate
* _- D7 }( `  I  phase                    ;; keeps track of the phase
' n% j2 c" b$ a: R4 q; s; Y" T  num-cars-stopped         ;; the number of cars that are stopped during a single pass thru the go procedure
7 n, {5 S& o; E) q( t, w  current-light            ;; the currently selected light
7 J$ p0 c8 K2 o
0 r! I" n$ H$ W* `/ u0 ?  ;; patch agentsets- k9 D2 C% S  {! m4 F) [# e3 B4 h
  intersections ;; agentset containing the patches that are intersections
& ]) X+ O$ J* t/ H; S- L( q7 W1 t! }  roads         ;; agentset containing the patches that are roads
) }) q: |. v/ Z. y) N; []
' F- ?8 w* s. a" Z" ?
7 Y9 R# v- ?3 v  b! u- r0 Nturtles-own
, f$ _+ g2 t# ?3 |( B7 `9 S[4 T7 Z$ n7 @$ v4 V" `3 P
  speed     ;; the speed of the turtle
3 C* u9 F, P. \  up-car?   ;; true if the turtle moves downwards and false if it moves to the right
2 q5 C3 X) R7 P, f  wait-time ;; the amount of time since the last time a turtle has moved
1 m0 D( g& P5 h  v' i! Y, ^]. n( k0 x. ]9 `+ B. _$ W# T( r3 l; |
! I+ Y8 P$ F) y  V' |& ]0 J7 g
patches-own
8 I* j2 g& n+ F" p) ]  v[% U& `8 w: p6 e6 w( b
  intersection?   ;; true if the patch is at the intersection of two roads
  y" \# N8 W' I( J* l9 O. `+ H  green-light-up? ;; true if the green light is above the intersection.  otherwise, false.3 G" q; ]# o! {# @: T( s2 W' O- m
                  ;; false for a non-intersection patches.
7 W# M' P& @# z5 f8 a% |/ ~  my-row          ;; the row of the intersection counting from the upper left corner of the* u9 |, T$ P# c! O" @
                  ;; world.  -1 for non-intersection patches., Y! K. k6 a: m* ?
  my-column       ;; the column of the intersection counting from the upper left corner of the& G9 l( z  h# C. U/ I* t. I
                  ;; world.  -1 for non-intersection patches.
& D  B5 B6 d& Y/ o  my-phase        ;; the phase for the intersection.  -1 for non-intersection patches.9 s9 d8 f/ D2 Z! e
  auto?           ;; whether or not this intersection will switch automatically.
; D, C4 O3 {! H                  ;; false for non-intersection patches.
" |( \: P3 y3 X$ _& s* E6 B* o]
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4 y+ q9 o! |' G- {! }; Z& J! _/ x
- J# I, f: l5 s7 ?;;;;;;;;;;;;;;;;;;;;;;
5 o7 N+ ], }) C2 Z$ |;; Setup Procedures ;;
# u% ^# i' a5 f5 K% l) i;;;;;;;;;;;;;;;;;;;;;;+ S- E* w8 y1 C- q1 \+ C
5 l7 r/ J6 b+ f& s& i/ T. Z
;; Initialize the display by giving the global and patch variables initial values.
, M# k. {2 r! C/ Y( z+ J;; Create num-cars of turtles if there are enough road patches for one turtle to
; ~) \9 s0 G  _0 ^3 l, [6 G;; be created per road patch. Set up the plots.. J% O' ~- B2 \- v
to setup
1 B2 p. Y" T0 r  ca; P5 G" P8 _* D7 x& I. {
  setup-globals
; w. r. k; n7 b% S" `$ ?3 `" r! O5 L$ r
; T; D1 S0 h8 o9 }6 Z  ;; First we ask the patches to draw themselves and set up a few variables
/ d* x0 T6 @' A. }. h, r9 r  setup-patches6 H" D! R5 v+ c: a) T
  make-current one-of intersections
& B" i0 O. E" U- ^  label-current% O. l$ Y2 L$ ~
: ^, A' ]# ~& x) Y: l, O" b
  set-default-shape turtles "car"5 y$ e9 X" P3 _+ _# u8 N3 y
1 X  Q# N0 B  w3 A' z& Q- r
  if (num-cars > count roads)
5 h; L! X3 T; U* Y' l7 M  [
' p9 \0 ~/ N, j: Y% Y    user-message (word "There are too many cars for the amount of "  c* ~3 \5 R8 k6 S* p
                       "road.  Either increase the amount of roads ", n: H9 X  j0 t  }  l
                       "by increasing the GRID-SIZE-X or "$ N, {8 h0 Q2 e! _$ ^# `
                       "GRID-SIZE-Y sliders, or decrease the "# E% o1 G" H3 K6 z2 A2 g
                       "number of cars by lowering the NUMBER slider.\n") G- n: K7 B2 F: Z. d+ T: g, I; i" L
                       "The setup has stopped.")
  R3 {2 @5 S" d& w    stop
3 ]/ O/ Y, Q6 Q% |8 E6 Y  ]
- v' h6 x7 ]/ a/ ]$ n8 W( [) L+ N! N+ S9 u, k: q5 ^
  ;; Now create the turtles and have each created turtle call the functions setup-cars and set-car-color4 k  E  a: |7 z6 B/ W
  crt num-cars! T) R4 }( R  O. p% s( J3 \# b
  [2 k0 g0 a6 f( ]. t8 k7 \
    setup-cars/ V0 K- i; s: C+ L" y1 @
    set-car-color5 X, ^) @, D9 |8 t- S1 P
    record-data# {, p4 Y7 z5 [  t
  ]  c! e( _# P* `, t: E1 T

7 R( `- ~& D. h- f% d  m, V5 o  ;; give the turtles an initial speed
% [; m- @- d* N7 K2 v$ Y" g3 x" d9 h0 A; _  ask turtles [ set-car-speed ]
, U+ `4 _0 H- X8 G' o* H- ~+ i7 i3 O
% Z( F( ?: E: d) Q) v, b4 z3 w" h  reset-ticks
4 o, g& L4 I9 X+ s& b) `: ^' qend% q  Z1 N& E! B5 m0 R3 d6 {  H/ ]4 d

- M9 z: p* |; r/ B& B;; Initialize the global variables to appropriate values! @* w6 V+ p; @" ]' w
to setup-globals
0 s- o* \/ i' Q  set current-light nobody ;; just for now, since there are no lights yet
' N  ?9 T, I' z* z7 }  set phase 0
  q! S2 r* V* c, P! P  set num-cars-stopped 0- Q0 I: W; Q; P' @% R" p& s. y
  set grid-x-inc world-width / grid-size-x8 B4 D( _8 F. M' e
  set grid-y-inc world-height / grid-size-y6 \7 x4 M. m1 r! J# [* u- e2 `. t
" ~/ x/ S- W5 Z8 x# Q2 z- l5 J3 T" F8 L
  ;; don't make acceleration 0.1 since we could get a rounding error and end up on a patch boundary
, d# D2 L5 T% q% M' ~  set acceleration 0.0991 f( l& \5 I* q  }# A5 X
end  s" }7 [+ K) m) K

9 u" n1 m/ C# r; s! U;; Make the patches have appropriate colors, set up the roads and intersections agentsets,
, v& r. e2 ^, m7 P' W( e8 z, A; c;; and initialize the traffic lights to one setting
1 v0 Z  f' q/ j8 _: K6 `( U4 ito setup-patches
; R: R+ b: |; R' V( G* U: k  ;; initialize the patch-owned variables and color the patches to a base-color
6 z, U8 q; b, K8 l2 m. r  ask patches, F/ V  S# \" O- e, z
  [
1 Z5 b8 t' h7 V3 a    set intersection? false
/ @  s4 _$ b, U! `    set auto? false
+ r$ V: m* j7 J; Z: _! f8 i    set green-light-up? true: Z# ~  q" \/ _
    set my-row -1
* u4 M* _7 Z) i5 y" r    set my-column -1" N5 u7 j, e6 F3 {( I" F& H0 m
    set my-phase -10 k5 w0 M6 t7 t
    set pcolor brown + 3' j$ W! `1 F0 M, x
  ]$ g! O5 o: w- o  D; `
6 }) M, ^+ _; P$ }& j1 j3 ^6 [9 b
  ;; initialize the global variables that hold patch agentsets/ h1 ?) Q, U. O% _
  set roads patches with
* V9 Q  h$ G7 k8 M' t& J; h9 W    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) or
( m$ Q/ w/ ~+ f9 d    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]/ w! q1 r- e0 K0 e3 }
  set intersections roads with
" K+ K7 v! `& G6 B: W    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) and8 `* T3 Z# }  U9 w, y; C4 D0 m1 @
    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]2 w, g" }7 C3 E6 N
. [+ J7 S* a% P- j* x* |" s! T
  ask roads [ set pcolor white ]+ N2 w. X$ ?, \$ @/ d- A' ?
    setup-intersections
% n' s$ ?4 V& n1 A( \4 Z# Xend
" v) g' {1 G  Y; t8 s4 J" ^其中定义道路的句子,如下所示,是什么意思啊?& l' |5 ]) V4 P/ F
set roads patches with/ H1 C% W2 a: v; x
    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) or
* I& q, k+ B4 }3 S, ]! B( m2 y& K    (floor((pycor + max-pycor) mod grid-y-inc) = 0)], L- T0 j: l6 y6 S
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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