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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。8 g9 ^0 h  G4 o2 G2 y
netlogo自带的social science--traffic grid这一例子当中,
5 Z/ l' B; S9 r8 Sglobals4 M- Y. f4 ]4 }1 L) w* H0 h
[
1 ?5 Q6 z* D* N- U! X  grid-x-inc               ;; the amount of patches in between two roads in the x direction
; ^3 i3 Y8 V% f9 p# ?  grid-y-inc               ;; the amount of patches in between two roads in the y direction' p  @8 w3 P9 y( W* l
  acceleration             ;; the constant that controls how much a car speeds up or slows down by if
' J& @  @* N3 z8 C. \! c6 j                           ;; it is to accelerate or decelerate  {2 l8 ^& g) V8 D
  phase                    ;; keeps track of the phase* v/ }2 i+ i, ^& {1 F
  num-cars-stopped         ;; the number of cars that are stopped during a single pass thru the go procedure
0 y1 s/ w/ X( v  Y$ ]  current-light            ;; the currently selected light. N6 ^/ {2 p) H  w

2 W9 q/ h8 M# Q6 R6 _  ;; patch agentsets1 ]9 S0 }, ~4 s' h
  intersections ;; agentset containing the patches that are intersections
& y% [6 h5 b4 R# o  roads         ;; agentset containing the patches that are roads) g, U) |% L8 k* z  @
]
5 a" Y; \+ O" u1 D% ?* `
  P) J! P8 T. {( Zturtles-own
/ U/ K0 c' n- k1 X# a, ^[
/ w$ A6 V6 A* \4 q7 c2 D9 F, O7 p& }4 @+ i  speed     ;; the speed of the turtle4 H2 e: n$ m  x6 I5 W
  up-car?   ;; true if the turtle moves downwards and false if it moves to the right5 \% \8 l) G5 ~0 H
  wait-time ;; the amount of time since the last time a turtle has moved
( l9 z+ C* ^+ l" c]
' |: F6 Y/ F' S( W8 P1 N6 L, }0 k* U# o( m2 |+ o( Q9 j
patches-own& t( Q4 w: H; h8 \% \% |
[: V2 j, k. i) [6 Y. z* B
  intersection?   ;; true if the patch is at the intersection of two roads
4 ]: L3 \. O# G  h- F+ J3 V7 w  green-light-up? ;; true if the green light is above the intersection.  otherwise, false.# x# U% ]! O; \2 D  A
                  ;; false for a non-intersection patches.- L, M8 P2 W# _+ d
  my-row          ;; the row of the intersection counting from the upper left corner of the
2 D( |5 t' F' H" ]5 D( U- I                  ;; world.  -1 for non-intersection patches.) _2 P1 M; f1 G
  my-column       ;; the column of the intersection counting from the upper left corner of the% l$ G" ~' P$ U- {! G: G, g* L
                  ;; world.  -1 for non-intersection patches.
, Z, k+ x2 b+ C3 h  my-phase        ;; the phase for the intersection.  -1 for non-intersection patches.
7 U- _. H) f% Y5 r4 T  j3 O  auto?           ;; whether or not this intersection will switch automatically.5 V! o: _" i) [1 ~# ]( f! t
                  ;; false for non-intersection patches.
4 `% u( K3 i6 y# y0 T]
/ `# R1 @2 j0 T
6 z4 }5 M) b0 @" y
% S$ U+ ^6 X. ~) H% i8 B9 O4 I9 o. f;;;;;;;;;;;;;;;;;;;;;;3 E1 t1 e! J9 ?' y+ w# h4 M& }7 f. B
;; Setup Procedures ;;
- @9 F' C, r  G' {# X; D;;;;;;;;;;;;;;;;;;;;;;2 H. i" s& z) H! [; L; U8 W7 B
% m- p' _; u8 |9 I  b
;; Initialize the display by giving the global and patch variables initial values.
) M1 J7 D! |% K. m: V1 ^;; Create num-cars of turtles if there are enough road patches for one turtle to
' E7 g3 R+ ?6 P0 Q. t;; be created per road patch. Set up the plots." |1 e% \0 _! c( y4 p% h$ p
to setup
: e6 U7 u; `8 h4 j4 ^  ca
& R% Y) o2 s  ?0 [2 i+ F: |  setup-globals
; N/ g- u% F( c1 [' d$ [; f& U: Y' U2 X
  ;; First we ask the patches to draw themselves and set up a few variables
2 g4 x' `7 B4 F3 A) v0 C' `  setup-patches
( X& u, T' ?) H( J/ Y2 _; {  make-current one-of intersections4 ^: m5 c6 f% L; Q
  label-current
# a9 _, X! s- d, y6 w1 u# x$ ~- ]( ~. H# H
  set-default-shape turtles "car", x1 S( U) d" I( N$ x
) z6 _! J" t* M/ C9 W0 l8 d; j
  if (num-cars > count roads)
* n) x: \% i9 Z1 U2 d% T3 o# R% ^  [
  _" a4 n* G, D4 S# [5 u    user-message (word "There are too many cars for the amount of ") e! J4 }* k0 x
                       "road.  Either increase the amount of roads "5 p6 {3 V/ g$ p$ ]3 a& p
                       "by increasing the GRID-SIZE-X or "8 s; _* h! t3 [; w! y
                       "GRID-SIZE-Y sliders, or decrease the "4 |/ v* t9 w+ K% C
                       "number of cars by lowering the NUMBER slider.\n"
+ g1 Q% K# d, \6 g0 N$ p% v                       "The setup has stopped.")
% o1 N  Z, L3 U% ~3 I# V    stop4 \2 _1 O  I6 k- o2 v
  ]: `/ Q7 [$ y9 X- x
& C, i, C( M, B1 ^( n" e( l
  ;; Now create the turtles and have each created turtle call the functions setup-cars and set-car-color
7 Y: q& r2 ~  G* J! F& h" l  crt num-cars, S, P9 G, h! S9 M% b
  [
" J1 _6 F" A7 v9 ?. C  s/ _    setup-cars
; i: f% m) V9 j* ?. J+ P: i$ P+ a    set-car-color. T! L5 y0 \1 h, P
    record-data
0 p- M5 w& T% ~- i' t7 ~( ?  ]" l9 S+ o" w: Y7 p6 x

' }. ?% ?( k8 u  I) G  M( V4 u  ;; give the turtles an initial speed
6 ]) J6 z5 k8 j; e  ask turtles [ set-car-speed ]. S+ |6 d. Q: A0 y2 `, n
+ r: e: e( P( \1 z
  reset-ticks
: y( C' ?, r5 `  u  vend
  x! `8 c& m" H0 ]$ }% x1 x2 j8 s/ o) c" N
;; Initialize the global variables to appropriate values
. P, O) b& I/ b+ V) Sto setup-globals
3 C( A; R6 v. t/ H: f$ R  set current-light nobody ;; just for now, since there are no lights yet
8 ]6 t6 K9 X0 j# S: O$ ]  set phase 0
; Q' {& p: T" {( U* J; N  set num-cars-stopped 0
3 c$ Y- L1 Z9 L% `. e& P$ T" q- Y  set grid-x-inc world-width / grid-size-x
- }9 h; A4 Y% y4 W' v4 E  set grid-y-inc world-height / grid-size-y, m5 d+ a  a. Y2 ^4 n% ]2 H
7 e/ F& \" h0 u3 F
  ;; don't make acceleration 0.1 since we could get a rounding error and end up on a patch boundary
& e+ t& u5 c$ {6 e" d  set acceleration 0.099+ y, `5 Z3 K/ Z
end' Q8 ]3 E. b5 y& `

0 z0 E$ N  Z# j+ H  o. [* {;; Make the patches have appropriate colors, set up the roads and intersections agentsets,
% b- j  g3 n& {- n;; and initialize the traffic lights to one setting
1 D+ |2 q3 m8 G+ p) o, C' o' Oto setup-patches
+ k8 z- ^8 P- }# ?0 @. H- H8 @! {  ;; initialize the patch-owned variables and color the patches to a base-color0 f; W/ W8 T8 R$ S- A) U, Y
  ask patches
2 Z- b; K! P8 X) ]/ T" a! Y2 |. E  [6 W3 _% b1 m, `4 S
    set intersection? false
# _- x9 O4 E2 b; k( }' G8 x% B    set auto? false7 y' g2 Y5 x% f( g, M& G
    set green-light-up? true% L" G' {9 B7 t2 e/ A! `0 c
    set my-row -1
2 v( E- q: \! Z4 [6 s    set my-column -1
) e; C" Z" N! H! H" r    set my-phase -1
7 h$ ^, c7 T7 x6 J5 {& r8 ?9 r0 _    set pcolor brown + 3" m1 ]- m; q& l: e0 h+ I  r
  ]9 L5 W6 ]) [3 {

: w, t  ?" p6 e6 L0 n* F  ;; initialize the global variables that hold patch agentsets6 C% F2 L4 B& r8 Y$ d
  set roads patches with1 j' f, r- e' B. q0 M
    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) or$ v4 W9 x* }, X9 P& Y% e# g
    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]
; h8 m1 \8 T7 K* F; e) j/ K  set intersections roads with: H9 k; i& i* x) J: T- ?6 B
    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) and$ h3 E# l8 q/ G" V
    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]
7 `% Z1 _  p& G( m/ `, b- x  a  J7 V- z3 e
  ask roads [ set pcolor white ]
" ~9 h) y" u) y+ C    setup-intersections
3 J; ~: `+ p+ _: {$ E' wend  x9 f5 }7 g* h% L. F2 ?
其中定义道路的句子,如下所示,是什么意思啊?0 F8 c* ~! N5 A  z6 Q1 j
set roads patches with$ o, R6 n  t! L6 h- X9 J
    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) or
7 V; e. w* j8 c7 `+ V+ w& p    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]
  p* O5 S( s5 N" `* ^7 Y( Y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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