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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。& r! x2 U, Y$ o
netlogo自带的social science--traffic grid这一例子当中,' \- d" j# \. c/ ]
globals
% I+ a' |- d! V[7 ]( C; p/ i' c) l
  grid-x-inc               ;; the amount of patches in between two roads in the x direction. `: ^: S- ]3 F# J2 L* j5 b- I
  grid-y-inc               ;; the amount of patches in between two roads in the y direction# r: I. a- {( c9 A1 P8 q
  acceleration             ;; the constant that controls how much a car speeds up or slows down by if) U7 P, t9 L, E2 r, I  L  a
                           ;; it is to accelerate or decelerate
) q3 l5 `! i$ @# l, H2 I  phase                    ;; keeps track of the phase
3 a6 t8 x. e+ d% ]2 A  num-cars-stopped         ;; the number of cars that are stopped during a single pass thru the go procedure$ z7 c% v) L6 `( A4 E4 i
  current-light            ;; the currently selected light
3 `8 E: H, H. |
4 `: |4 R' i* s" U- Y5 R1 l! H  ;; patch agentsets; O, ?) A4 n- X  T1 a) |
  intersections ;; agentset containing the patches that are intersections$ b6 \# }4 }  m
  roads         ;; agentset containing the patches that are roads
9 I# o2 T; t, M# n]
0 ?: n: r$ [5 {) o" a" P6 x: \1 Z6 R( O  U9 e
turtles-own& q3 U1 C; F* f+ x" z
[
- a5 A5 i% T% d" s2 k  speed     ;; the speed of the turtle
1 \4 F& l% p0 z  up-car?   ;; true if the turtle moves downwards and false if it moves to the right
. O3 C7 E& Q& O6 o) `" W, s  wait-time ;; the amount of time since the last time a turtle has moved
+ D1 l# k6 a* C4 |4 G- Q]
8 H% \+ Q# A: O! M  v  h3 g9 h/ d8 v  O1 ?' L4 B
patches-own
9 R9 _. g- K& ~[% m% v% I' k% @3 c1 H
  intersection?   ;; true if the patch is at the intersection of two roads) Q, _2 F* ?! |
  green-light-up? ;; true if the green light is above the intersection.  otherwise, false.) }& }2 E0 J2 d) j: ~8 i3 w
                  ;; false for a non-intersection patches.
- G- H/ ~8 @$ y2 Z# d0 E# Y% ~  my-row          ;; the row of the intersection counting from the upper left corner of the
8 d0 @9 i! A! u$ i4 y% u8 h7 V                  ;; world.  -1 for non-intersection patches.+ K" m5 y5 b: ]/ t7 _; f) |6 L
  my-column       ;; the column of the intersection counting from the upper left corner of the6 a, Y! L  b0 l* M& E* c. Y
                  ;; world.  -1 for non-intersection patches.4 {9 c& v3 F2 x* k& n3 c
  my-phase        ;; the phase for the intersection.  -1 for non-intersection patches.
7 B% T6 u+ o, g  auto?           ;; whether or not this intersection will switch automatically.9 y# L  g$ h& q( f3 Y! m
                  ;; false for non-intersection patches.' Y9 }- q$ q/ f* M+ `% |6 P9 b
]6 Z- W0 G( }4 M3 b
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+ ^  H& j9 K% @( D, n9 r( {. V
;;;;;;;;;;;;;;;;;;;;;;
9 F; @" E/ A* \! d/ ~. R' v5 X;; Setup Procedures ;;
' m# N0 Z2 b. B7 v;;;;;;;;;;;;;;;;;;;;;;% M4 b- K. T# f7 M9 w5 k$ i
0 }9 u0 l8 `( z8 y0 n1 Z
;; Initialize the display by giving the global and patch variables initial values.
/ X4 ], S! V. p- K;; Create num-cars of turtles if there are enough road patches for one turtle to* `/ Y, A0 c) o3 U) @
;; be created per road patch. Set up the plots., W# `4 y7 X; S! S  x. g
to setup; ]9 f: D- i- i
  ca
. u' g* a0 Y5 c  setup-globals6 o  s; _8 G0 f

0 r6 Y0 p' Y$ ]" B  ;; First we ask the patches to draw themselves and set up a few variables5 h+ o+ y2 U  t& n! b' g
  setup-patches
3 i" e# m7 \  \: v% j& o  make-current one-of intersections% c4 j6 G- V3 L) G) u2 y& F+ n
  label-current
* c* e: Q3 A& R  u: h
; ]+ i+ h4 ?  A/ f1 F& |  set-default-shape turtles "car"
! y* ^" M+ g3 a: c" t$ [  ^. ]' |) ^0 i6 n. _& n7 I
  if (num-cars > count roads)
3 G3 W; d5 q( `% b- Z# g  [, O% \$ U1 d* ]$ E) r  {, C
    user-message (word "There are too many cars for the amount of "
0 P; e) A  Y( D* _3 N                       "road.  Either increase the amount of roads "2 R+ x$ {3 x$ @0 f& d' l$ q
                       "by increasing the GRID-SIZE-X or "4 Y2 }9 m$ o% ]9 }1 F
                       "GRID-SIZE-Y sliders, or decrease the "# g, r% F  c9 j# {  p6 P4 h
                       "number of cars by lowering the NUMBER slider.\n"
- n  k/ [9 @8 w3 q% L% [. g                       "The setup has stopped.")% x! R$ ^9 \# [  W4 |
    stop5 I0 q1 x. ^  A0 u+ u% V; z
  ]* V$ c. R0 f, Z  V

+ e+ n8 W# f  P& ]; s& z  ;; Now create the turtles and have each created turtle call the functions setup-cars and set-car-color: x/ S  t. T3 V/ j, m* U
  crt num-cars
& L# Z0 {: |& @0 b  [
. b7 E) T2 ^+ }    setup-cars
" A7 @  z; `! d+ U6 v    set-car-color" `9 e9 Y1 k# n: b7 c/ o
    record-data8 z4 i5 ?; N0 O
  ]4 t" X. l1 y; h1 P: ]

5 A& Q2 \8 P; Y8 j7 [6 k  ;; give the turtles an initial speed4 c3 }, ~0 j( j7 h7 f7 w9 V/ ]1 w
  ask turtles [ set-car-speed ]& L4 _# C8 @9 B: m" U* P. e
( ]6 j* a3 y) D* m: V
  reset-ticks
* v/ {4 {. i! H# }3 W$ Y) mend# m1 l& b' F7 x9 S4 d- ]. i: i

2 q2 G2 [* k" I0 E;; Initialize the global variables to appropriate values
( B) o# r0 h& E& `8 eto setup-globals8 d; q9 L4 @1 g
  set current-light nobody ;; just for now, since there are no lights yet
- D6 f# O& ^: e  set phase 0
/ q8 O0 C6 z, `! x  set num-cars-stopped 0
- R) @) {: _: Y4 d( c- r  set grid-x-inc world-width / grid-size-x" L1 ^% J8 K" s  p1 R+ G. H
  set grid-y-inc world-height / grid-size-y
6 p- O8 L8 d+ V$ _7 L& K4 F2 Y
% J0 Q& P3 o  w/ P% s7 P  ;; don't make acceleration 0.1 since we could get a rounding error and end up on a patch boundary
& G4 z, h5 w. O1 d3 j) D  set acceleration 0.099
3 u$ q! R0 R" H( R* b+ ?" tend
! |2 A0 O' d$ v3 e: d
' q- B; z0 W1 i; P;; Make the patches have appropriate colors, set up the roads and intersections agentsets,
) y7 v. ^0 K. i;; and initialize the traffic lights to one setting
& [- k" M; t, w6 l  K  ^* p4 F2 O3 f  jto setup-patches9 f. h) i' c( l) @5 Z5 m
  ;; initialize the patch-owned variables and color the patches to a base-color$ u' B" d7 W0 k/ ]6 Y* r1 S' Z/ x: u
  ask patches# ?. K* c# I* k# I9 a5 j" E
  [) g2 i0 ^' `! [" o: y$ j
    set intersection? false
* U/ `5 z# T; y; b. t    set auto? false7 ^7 g. y6 ~0 D8 W* M. a
    set green-light-up? true& @2 U+ t9 o2 P; @
    set my-row -1( p5 J7 H+ Z* L8 D
    set my-column -14 w" d- C' U: v. g4 v' k: b
    set my-phase -14 q( }2 [4 C$ y( S! u* J9 i& y
    set pcolor brown + 3* e7 S. @: l7 {+ C  U7 j
  ]
, D1 K# i, |6 Z4 z# _3 b6 n
) z: x1 ~; K0 c* V  ;; initialize the global variables that hold patch agentsets
. k1 D! r+ {" p5 y. D, T3 w  set roads patches with
3 Z  j; V8 T0 I" e/ r% S    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) or
1 b. L  D& r- b- O& [    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]
- V' ~; B  b+ R6 m( H; G  set intersections roads with
. o: ^% i. \; L) D6 y0 z% u7 W    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) and
: S; j7 p' h1 K! X6 l/ L) X; W$ p3 @    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]
/ q/ C) R: y( a: p6 w5 S: G! q- Y; Y$ f
  ask roads [ set pcolor white ]$ {$ S( c5 T+ K5 H
    setup-intersections
; ?  I; O; P4 U' kend
" N* H1 m  K4 U" j1 K其中定义道路的句子,如下所示,是什么意思啊?
6 P5 ^7 S5 o3 `1 i# ^7 H. h set roads patches with
2 O+ V9 C, V  i+ S& J+ K' a    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) or
4 O9 i# n$ d9 }5 t' l$ K4 Y$ u    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]
& J) ~$ a7 S$ 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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