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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  s! G# w% X( M4 `
netlogo自带的social science--traffic grid这一例子当中,+ m9 P2 a0 {, |  b
globals
  h" I. c' N( Y5 O6 F7 s0 b[
9 v6 o5 t$ d8 r- q- J1 Z# V  grid-x-inc               ;; the amount of patches in between two roads in the x direction' t! e* n  g/ d8 R! t/ `( X) Y; L+ I
  grid-y-inc               ;; the amount of patches in between two roads in the y direction1 y8 U) p) J3 l* r( h
  acceleration             ;; the constant that controls how much a car speeds up or slows down by if- M: [% b' o  U0 Z$ d: g
                           ;; it is to accelerate or decelerate
, L+ g& U. M6 w  phase                    ;; keeps track of the phase
# [, U. S) f6 |, o  num-cars-stopped         ;; the number of cars that are stopped during a single pass thru the go procedure
, j' G) X+ _# o: p. T  current-light            ;; the currently selected light' o1 f- x$ J: V! e5 \0 d$ ^& @
% V9 z, _: S+ J! I
  ;; patch agentsets
' \5 O5 t2 l" M! k  intersections ;; agentset containing the patches that are intersections
; H3 V( ]. I% ^8 E- t; W% x2 ?9 M- X" ^  roads         ;; agentset containing the patches that are roads' f# V4 [& \. B2 \) m1 b
]
9 `: c9 T& v, _
$ K5 ^: E1 h/ H- u+ Lturtles-own
( T( J4 E2 l6 o5 ], \/ i[: ~* t9 ]- k9 t
  speed     ;; the speed of the turtle
0 D) j- z0 }. x" [4 v; ^" F& k4 t+ Z  up-car?   ;; true if the turtle moves downwards and false if it moves to the right
9 g. s5 L( o) R; {, G# Z  wait-time ;; the amount of time since the last time a turtle has moved
; z, w1 \) n6 e]2 q5 ?9 F; W- s! Q# @9 K+ _

! W8 P3 S6 B( p* f6 Cpatches-own7 b" f5 I9 n0 _8 u7 J
[) y* r$ N6 L# B
  intersection?   ;; true if the patch is at the intersection of two roads8 a8 t! L! s0 e8 L
  green-light-up? ;; true if the green light is above the intersection.  otherwise, false.
% r& `' w9 b7 d0 d' x! v4 @                  ;; false for a non-intersection patches.
9 m' h1 }+ Z) Z3 _  my-row          ;; the row of the intersection counting from the upper left corner of the$ J7 L3 d; v* A3 q2 R7 L# I
                  ;; world.  -1 for non-intersection patches.1 a, S; S# Y" L- R
  my-column       ;; the column of the intersection counting from the upper left corner of the/ l' w( T0 t; N1 B! m! b; r
                  ;; world.  -1 for non-intersection patches.% K/ M8 M: g" B) [. q
  my-phase        ;; the phase for the intersection.  -1 for non-intersection patches." g2 ?$ m: F! ]- q
  auto?           ;; whether or not this intersection will switch automatically.
4 H$ U" N+ T" u                  ;; false for non-intersection patches.
1 @* Z* @" ?4 u& n" L3 O8 z]2 O) F% I( b/ V; @- C
8 E& N2 @- @, S4 G* }$ J. T
5 T# q- e+ o5 r- L
;;;;;;;;;;;;;;;;;;;;;;' \: Y5 Q3 ]4 h0 W3 C, V* `& D# f
;; Setup Procedures ;;
' L: y+ M. R6 _: r. {5 T;;;;;;;;;;;;;;;;;;;;;;
3 @+ w4 K- d, V1 p' J; A' \& y; |* Y& V) i* k1 }6 i/ _9 L
;; Initialize the display by giving the global and patch variables initial values., f% a# y: t8 Y3 @+ z4 S
;; Create num-cars of turtles if there are enough road patches for one turtle to/ j6 P6 Z% }$ Q6 J, ^  ~
;; be created per road patch. Set up the plots.* s% A; J+ R7 y, \/ z5 R
to setup
  Q. A% T7 \% W" B* ~  ca
( ~, }$ A# O$ f( E- D6 [, @  setup-globals& a1 J0 P6 l; t) k* A' Q: n! D

$ q' X9 H: K, U  ;; First we ask the patches to draw themselves and set up a few variables
1 _: w5 b  R' K- e& |/ F* J/ y  setup-patches
6 Z% p$ D, p5 K/ ]  make-current one-of intersections
7 f3 x+ p9 t% m* t) J) T8 T  label-current8 O) P  R% X) e7 }

5 ~" X7 {- v9 w9 O0 S. k  set-default-shape turtles "car"2 m* v0 j# R4 i) @9 H1 G+ w

; N# @; c9 Z1 l  if (num-cars > count roads)+ i+ v: u: m: @2 d( t
  [
" p4 r0 @' f0 L2 Z    user-message (word "There are too many cars for the amount of "  M, p- H, Y9 G2 \
                       "road.  Either increase the amount of roads "
" E/ l5 U- v( G# W% _  m' {$ B                       "by increasing the GRID-SIZE-X or "2 }9 ^& }& D1 T0 Y9 X; L* \$ z
                       "GRID-SIZE-Y sliders, or decrease the "
1 Z. m& N7 z3 `1 p3 [% I9 M$ B* `                       "number of cars by lowering the NUMBER slider.\n"
/ k2 U* |) z" t                       "The setup has stopped.")) `; T6 W7 B+ G  z1 U
    stop
8 H: N, ^4 D% B4 P! l  \  y  ]; X8 |6 b) N7 E" z" W- p1 w

4 o2 L2 e- F2 g1 Y  ;; Now create the turtles and have each created turtle call the functions setup-cars and set-car-color
7 ^# f! J' g5 ~4 q1 m- h  crt num-cars& e( h! U8 U8 @" e* S% U
  [
7 S" z$ ^4 J1 z3 w) ~' ?    setup-cars
  x( N; ~$ m! Q) L, c    set-car-color
/ l$ a) t; [* I& M6 G    record-data
3 @$ s$ n0 I: K# D  ]
" E6 P( q5 g- ]( H5 [/ O
7 x8 E1 X- b8 y/ q3 [# ?  ;; give the turtles an initial speed
6 O" n' Q- w! E. T  ask turtles [ set-car-speed ]
% C. w% Z  C8 u( g% p% t$ r) Z$ T% I, V! i- U4 ~
  reset-ticks
$ s( S- R/ D0 i/ s3 Qend
, a8 a: C! n# d# O! E
. w, r: \& A+ e! w;; Initialize the global variables to appropriate values$ {2 D" \3 D& g+ H
to setup-globals- e- m- |  }) j6 ^% Z- b
  set current-light nobody ;; just for now, since there are no lights yet
' _8 d9 U6 n/ K3 q% [) d  set phase 0
6 Z! T  F3 v) _$ x% R  set num-cars-stopped 06 c  v6 I) G  c+ o
  set grid-x-inc world-width / grid-size-x, o8 O5 x5 F5 y% N  L
  set grid-y-inc world-height / grid-size-y$ Z8 C, }) O1 F
9 [7 e2 h; O; K/ \; Q8 |, U
  ;; don't make acceleration 0.1 since we could get a rounding error and end up on a patch boundary
: Y  n# b6 D; r" B1 b- H  set acceleration 0.099/ a8 T$ R- |* I. ^1 J8 g
end
$ |( G- U# L( M/ M+ ^- R* V
# Z, U- |; [0 m) b/ j0 ~;; Make the patches have appropriate colors, set up the roads and intersections agentsets,
, v3 `$ r# r- O% Z* d0 x9 U# y* Y;; and initialize the traffic lights to one setting. P+ T1 y3 Z% u
to setup-patches! ]% }8 Z, }& \7 M+ P/ a' ]7 A) C
  ;; initialize the patch-owned variables and color the patches to a base-color
& U+ K: O1 l7 N- w+ D- O$ s  ask patches
8 b0 G! z; v/ z2 S  [
( W4 e8 z+ L3 U" G- i) _    set intersection? false% ~! a& b( J+ h' Z$ E
    set auto? false
* x0 e& x) J# ?& d! c; ?    set green-light-up? true
8 y1 X+ u  G8 m    set my-row -14 B8 J$ M& C% A( T% @. P4 F1 W+ E4 g9 s
    set my-column -1
' l9 `' @5 G  b+ y) B    set my-phase -1
: I9 w( V! g3 u8 @' a5 m' Y: H    set pcolor brown + 3' }2 ^, Q& \! c0 g- A6 J; [1 H0 @
  ]+ {* _! }0 {  l+ P) \6 D

8 t" \" [) ]" u" I& o) B0 O# G  ;; initialize the global variables that hold patch agentsets
1 y  i( P! @2 }# _( u; \- n7 k  set roads patches with* V6 @! G4 ~" ?# _! l( q
    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) or
/ ~! H# e$ S7 A0 j& U) Y2 V9 X    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]$ Y. S/ }2 Q9 T' \- J
  set intersections roads with
6 S4 k/ j  F8 L  u( G5 l+ F, s' b( k    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) and
9 o5 x9 V8 `  C0 s8 n4 }    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]: N% V2 Y3 z. |4 \& `5 C1 E$ e+ s
. i2 B& W$ ]* Y" X! p. ?
  ask roads [ set pcolor white ]
9 G7 z% ^5 R7 w; {7 q    setup-intersections
1 ?' c& ~) U7 v' y3 \- m( jend4 D& M: c: p  A2 ]- V4 Q" }# A3 A
其中定义道路的句子,如下所示,是什么意思啊?
5 v1 F7 H/ V- b( Y  w( I- p set roads patches with
6 l# g+ a( f: H1 Q    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) or* o, Z* j3 u1 W. }# y/ {
    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]1 r- B9 u% Q# }" ^: D+ y* [' {  P9 q
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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