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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: |6 A0 w6 l. n' ~9 ^
netlogo自带的social science--traffic grid这一例子当中,: b; u! c. Y9 g- i
globals, x9 X% q& h9 S
[: x$ |6 O( e* Z: F. ?$ Z) r5 M! j
  grid-x-inc               ;; the amount of patches in between two roads in the x direction
  _% K$ s2 H2 H5 P6 i8 B4 m  grid-y-inc               ;; the amount of patches in between two roads in the y direction
1 M! t! b: t, ~  acceleration             ;; the constant that controls how much a car speeds up or slows down by if0 K$ ~* e  }7 a6 f; Y3 @3 y
                           ;; it is to accelerate or decelerate7 H8 F8 U8 o% V' m+ |
  phase                    ;; keeps track of the phase+ S2 l* M6 w7 v+ H/ E
  num-cars-stopped         ;; the number of cars that are stopped during a single pass thru the go procedure
8 i4 O, G* }& N8 R  current-light            ;; the currently selected light
8 B& K" b3 R7 y0 w: ]. Y/ E
, u+ x' `" ^5 x  K2 X  ;; patch agentsets( I# ~  n3 V5 `9 f; C1 y' r
  intersections ;; agentset containing the patches that are intersections8 j1 |- O9 h, h: T* q2 b& F; d
  roads         ;; agentset containing the patches that are roads# w6 m) o' M3 V( @% Z
]
4 o7 X3 z( f/ K7 [" x( `! t6 y) @* w( q# F* e; A/ s
turtles-own" w& v7 D( v' s9 i( e* p3 V
[2 q% @( D7 y* a
  speed     ;; the speed of the turtle
4 ]; K. K1 ~8 Z% Y5 K8 S  up-car?   ;; true if the turtle moves downwards and false if it moves to the right
3 ^$ W* p7 k" ~2 _: i9 W, `  wait-time ;; the amount of time since the last time a turtle has moved: @- P' S$ R0 B1 Y
]
3 G0 M7 z& y5 [: |) A8 M  `+ b: J
" x3 I5 r5 R) }& C7 d/ Wpatches-own* N+ n! G* E0 c- p$ j1 Q7 c! n# l+ ]
[
5 f. s7 \! Y& Z) n" ^/ p& B6 M  D0 A  intersection?   ;; true if the patch is at the intersection of two roads
! U9 R. J/ Z6 Z" R+ S  green-light-up? ;; true if the green light is above the intersection.  otherwise, false.' _7 d$ K* \$ a/ t
                  ;; false for a non-intersection patches.
, `- L6 o. R% r$ m) z1 O* S8 V  my-row          ;; the row of the intersection counting from the upper left corner of the
" F# m6 @) F! m5 K9 |                  ;; world.  -1 for non-intersection patches.
+ k: ~& w  k' W# {* u: [4 V  my-column       ;; the column of the intersection counting from the upper left corner of the; C2 E0 B' a6 y$ q: h  D$ y" @3 A' y
                  ;; world.  -1 for non-intersection patches.$ u3 O/ J7 w7 K* Y
  my-phase        ;; the phase for the intersection.  -1 for non-intersection patches.6 i/ ]- a1 u& `  a& D* T, K: Z
  auto?           ;; whether or not this intersection will switch automatically.. x/ j# E2 }/ W& o
                  ;; false for non-intersection patches.
' o# G* w" q" f1 p, c. W]
7 M6 s* h* ?: z4 N- b3 d
' v$ m5 Z6 _' R: b$ T* j, g( N9 J
6 U4 e; Q5 Z1 i& a5 h) W' _;;;;;;;;;;;;;;;;;;;;;;- S; n: F; k# D- n- t8 |
;; Setup Procedures ;;
) E* _- b1 V! F6 k% f/ b;;;;;;;;;;;;;;;;;;;;;;4 q8 ]0 m) M$ ?7 s, f9 w1 I

" J) s. J) p, F' k( y;; Initialize the display by giving the global and patch variables initial values.4 G7 n+ g5 T9 w& b
;; Create num-cars of turtles if there are enough road patches for one turtle to
; ?3 }# V9 a, [;; be created per road patch. Set up the plots.
6 H. h* f8 y; {1 o5 L$ o1 \to setup0 y6 j' Q. P5 h0 A- ]( [) C( C' ~' l
  ca
9 ^1 a! C) {' I3 F% I3 F4 X  setup-globals
8 Y4 s7 q* u) C# a3 W
2 j5 J% x* b" ]6 c) I& v+ k6 [  ;; First we ask the patches to draw themselves and set up a few variables! B, K; W( Z) |) S+ S( ~7 K8 {
  setup-patches
0 \$ e* F3 T+ K  make-current one-of intersections4 c2 s  Y# R9 {$ h
  label-current5 G! v! u& J2 K5 p# U
- D! x+ I9 L" h6 G8 X1 x' `* [
  set-default-shape turtles "car"
. x5 {0 R! }8 i" C! S5 ^  y% V& E8 ?5 A, t7 R$ F  X( k
  if (num-cars > count roads)0 J3 w2 A% L3 M
  [5 s$ ^1 u4 J1 C* K3 p" j9 z
    user-message (word "There are too many cars for the amount of ". t% x# A' a. t! D! H- g) @' e
                       "road.  Either increase the amount of roads "; o$ X! F0 D' A- M' C! k
                       "by increasing the GRID-SIZE-X or "
! }3 m* n2 G5 a3 Z                       "GRID-SIZE-Y sliders, or decrease the "' c- r1 ^4 O# x/ i3 n
                       "number of cars by lowering the NUMBER slider.\n"9 \( @' Y1 X) j! R3 f
                       "The setup has stopped.")
/ b7 b  J6 B) W% P) o3 \; v6 \- l    stop
: N" s2 Z9 m! g, Q- y( C5 N  ]; Y  d2 R4 g: n0 i5 Y! E

7 K1 F( S( U/ Z. o& `  K  ;; Now create the turtles and have each created turtle call the functions setup-cars and set-car-color
: U$ X/ F) \9 T) y/ b( H  crt num-cars
  N7 u- P- z) I7 q5 L/ g  [
5 N7 x! A2 B4 i# S, W5 ~. }    setup-cars
. E, w% w# _3 r- R# M    set-car-color
9 e/ W3 l4 E& `  _    record-data
3 o9 d) G1 w& M7 d, H4 @2 j  ]
  m2 ]5 I& U0 f: |, _: s& U/ `8 _1 }& N
  ;; give the turtles an initial speed
; z; `3 @) w" h" ~; N  ask turtles [ set-car-speed ]
2 ^4 m1 z4 |; p+ M$ m
: Z# _  Q9 g" S/ x& r4 Z, W+ z; P  reset-ticks. g5 G' y9 i5 ~: C% Q& G
end
5 Z: O9 O, I: b% [) b/ |7 K
1 Z& {" v8 s2 ^, [;; Initialize the global variables to appropriate values
& y. S( z' G3 G5 Ato setup-globals
+ X4 U1 x/ ~( H: r* y) L3 ^4 N  set current-light nobody ;; just for now, since there are no lights yet  M& }% S5 `+ o8 f5 j( g
  set phase 0
- U* v  g# j$ Q5 |, H  C3 L  set num-cars-stopped 02 r/ b2 f2 v1 g5 r, m) k+ ^# {
  set grid-x-inc world-width / grid-size-x$ v. r, x5 G2 `) X$ G
  set grid-y-inc world-height / grid-size-y
# r/ p4 V8 a- S/ J! y. Z' X) J5 X6 Z" M" d. E
  ;; don't make acceleration 0.1 since we could get a rounding error and end up on a patch boundary0 G% ]0 t4 d3 T% T- T) {
  set acceleration 0.099+ o! _$ k& F- E! m3 p" k1 u
end
" K& G  x& }- v+ s
( B8 _# A  V7 p2 Z;; Make the patches have appropriate colors, set up the roads and intersections agentsets,
) Z% g* J5 g" Y4 d$ @;; and initialize the traffic lights to one setting
6 p. P9 }+ R+ V  n- D6 xto setup-patches" }4 E4 L6 N. U7 \1 Y" Q
  ;; initialize the patch-owned variables and color the patches to a base-color
" @; x; C+ D5 [" J( t# |0 k  ask patches: @/ |" |" b: K1 o, U5 M- c! G
  [2 y0 t" g0 U! e0 X. |
    set intersection? false4 i& P$ ]" _! Y# e  C- m0 |
    set auto? false
6 v- }" t; y5 Z5 V* P1 C: m    set green-light-up? true
6 T8 Y5 ?1 o) g$ |. H" @4 f) B    set my-row -1
% \+ p  A( Q0 B: I* ~$ A    set my-column -1
& k1 v8 J/ \  S* ?0 z    set my-phase -12 b' C5 u  {8 U, [6 u
    set pcolor brown + 3; G3 A# n9 K+ W2 a+ L! K/ A. r
  ]
# Q& N5 G% l! F; V- G: I: ~! f+ a4 ~  `0 R% E* l3 V
  ;; initialize the global variables that hold patch agentsets& m0 p3 ?6 T1 n+ _* X$ E
  set roads patches with
: E# m9 ?4 F- A* F    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) or9 b+ j0 s% _% C5 b
    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]
  x9 a4 ?1 G7 }- Z  set intersections roads with
, e& I0 t+ H5 _; h" C8 c$ q/ {    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) and
; \& y/ O7 i) p7 u    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]2 S8 _3 C9 j  L( p+ X0 Q

' d) S" P+ Y4 ?1 {: R0 u  P  ask roads [ set pcolor white ]4 l: P) s( }7 B5 Z9 S8 d
    setup-intersections, y( g4 f8 r* x% r$ _
end
! p1 p, u4 t# h' I, ^其中定义道路的句子,如下所示,是什么意思啊?* s9 d2 f9 \8 z( a& h; y6 `. M0 `
set roads patches with# C5 H+ y, a6 C$ O
    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) or  r+ ~6 K( i+ T9 f' m) v
    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]
% F; O! }2 q  A3 i$ @, |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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