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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。
. c0 ]1 ?0 }2 o$ ~6 Hnetlogo自带的social science--traffic grid这一例子当中,
+ ?% O" v, T  h7 @  F: S: `  U7 N. bglobals% T, ^$ h0 i& g6 k
[
& e7 H: \7 y1 G6 @  grid-x-inc               ;; the amount of patches in between two roads in the x direction
& E% q* _) V" o: Y# _6 m  grid-y-inc               ;; the amount of patches in between two roads in the y direction6 t, `7 k, |* A* N! a. X8 H; r
  acceleration             ;; the constant that controls how much a car speeds up or slows down by if- V0 `( ^" w, U% Q3 e( n/ `; H
                           ;; it is to accelerate or decelerate9 w, P) n1 f$ }
  phase                    ;; keeps track of the phase
$ u1 I- |5 O9 {9 O9 {* c3 J  num-cars-stopped         ;; the number of cars that are stopped during a single pass thru the go procedure
2 R% C; a  N! i2 n- a  current-light            ;; the currently selected light
, V" s  L0 o! E& {! F2 {5 P+ K- a
8 R; R$ h3 A* e0 u4 e2 \! w  ;; patch agentsets4 }7 z2 R% i% V$ z: g9 N
  intersections ;; agentset containing the patches that are intersections5 ~! ^& j- f0 o: U  c0 ^
  roads         ;; agentset containing the patches that are roads
) P7 L" |& B. W, u, A( ?3 t]
  K0 @1 i  p# @( c! B/ z
, S1 J7 H5 i8 H, `turtles-own: w% ?' _1 a7 P# T- T3 q" x" ^
[
- L4 j/ @* k9 m  speed     ;; the speed of the turtle
* j% i0 F. @. ~6 n+ A$ }$ g$ B' z  up-car?   ;; true if the turtle moves downwards and false if it moves to the right
% {+ E. ^7 A& i3 j8 G  wait-time ;; the amount of time since the last time a turtle has moved
! [! o1 S0 n1 }# ^& _]  a: Q) m$ ?# g! y+ O

  N. S8 p) F9 J* A" O; Apatches-own4 p) R! n: b2 j, g4 u
[
9 j2 \# Q+ o* Y4 L9 G  intersection?   ;; true if the patch is at the intersection of two roads: J5 `, y- y3 ^) B3 r5 v' J
  green-light-up? ;; true if the green light is above the intersection.  otherwise, false." w( _8 J/ ^6 K( P# o
                  ;; false for a non-intersection patches.6 i" w( c$ Y% V7 r2 e
  my-row          ;; the row of the intersection counting from the upper left corner of the
- J3 K- P6 a9 J! T3 S0 K                  ;; world.  -1 for non-intersection patches.1 E2 Y& l( M% P3 v
  my-column       ;; the column of the intersection counting from the upper left corner of the% T8 Y6 _  ]7 X
                  ;; world.  -1 for non-intersection patches.
/ w1 s. A$ |- T5 r/ K: i  my-phase        ;; the phase for the intersection.  -1 for non-intersection patches.
+ e  W; S+ _1 _% |; F1 O6 g  auto?           ;; whether or not this intersection will switch automatically.
/ @) Y/ g: `* r5 M                  ;; false for non-intersection patches.
9 ^. p; T  Z% K]
5 S# B1 L( A# a
. ^2 L  |% E+ O" v0 H% Z. T# C& C. u
2 e8 a% L% ]1 B+ V+ D' u;;;;;;;;;;;;;;;;;;;;;;
- J# ?9 W; `1 }. D& E+ Z. u. B. [6 D;; Setup Procedures ;;
4 D8 V) A; P, f2 [& l# V$ n# ?3 z' l;;;;;;;;;;;;;;;;;;;;;;
5 K# D* U) M( `$ N: Z/ H# Q: G  @9 R+ \4 u+ y
;; Initialize the display by giving the global and patch variables initial values.+ ]( h+ s- k' O7 J& v! n9 i
;; Create num-cars of turtles if there are enough road patches for one turtle to
9 K2 K  t& N9 f5 ^;; be created per road patch. Set up the plots.
( A3 {6 G, _6 X7 M; D5 E, F  ?) l0 _' {' ito setup
9 g- L7 s/ _( l* b" z  ca' A: ?( b: I; V" r, W
  setup-globals$ j+ P  N( f+ V, U

3 G) N2 P/ M( T) e* Q  ;; First we ask the patches to draw themselves and set up a few variables* b! |6 C5 Y- N: [% P" L/ t
  setup-patches
/ _5 t- }6 b) n3 B; L+ b" k( ]  make-current one-of intersections' O; h, B  S8 |4 T, W
  label-current
- n  I% s# g9 d( L: U
% j4 C; _; t, L2 O  set-default-shape turtles "car"4 O9 j( m: w! C# w9 |0 a1 L

  i9 Q' B- S+ E  if (num-cars > count roads)
: O/ z; n* U, o4 K* ?  [; |' q! `/ p$ s) G( D4 B2 p
    user-message (word "There are too many cars for the amount of "
7 Q, F3 u. s& f2 R( v0 b7 g4 ^                       "road.  Either increase the amount of roads "
( x4 R5 A- Z0 P* `5 p& {( O; A- I                       "by increasing the GRID-SIZE-X or "& z' {3 A" ~3 v; X, D& a
                       "GRID-SIZE-Y sliders, or decrease the "
7 f4 k& Z! q1 k$ r: l                       "number of cars by lowering the NUMBER slider.\n"
$ v3 k  G5 T* U6 k6 h: p$ s; Z- J                       "The setup has stopped.")
9 h2 o: I& r* `" K6 Y9 ?. |    stop7 }. M  J& J* L$ O" ]; F# V
  ]6 D0 P( _' z/ m% e

- R7 R9 r. W$ |- W; e  ;; Now create the turtles and have each created turtle call the functions setup-cars and set-car-color
1 R5 o" Q$ K; D0 ~7 L  crt num-cars
; y" C% x5 A8 q1 z  p4 E* ?  [- e/ O9 {! z/ A' z% W1 o$ A% z3 W/ y
    setup-cars
* E( J) y3 E3 [! r+ [7 S    set-car-color9 L; f- V/ l5 X* u6 D0 q$ m1 h1 ]
    record-data
5 t$ Z; |  w! V, k  A  ]
+ S8 W2 n8 E. T( c
- p+ Z1 j6 S9 R$ r% P8 y  ;; give the turtles an initial speed, e6 T& @8 G+ l: E, I; `
  ask turtles [ set-car-speed ]. `  X" k+ i7 [
& |+ I  \$ k0 Q5 j9 ^
  reset-ticks3 N, x: e3 D- L1 R' {! \
end% H1 A& A  E; `
# V+ @$ |7 T9 x3 o1 L
;; Initialize the global variables to appropriate values
! `, `9 a" I+ ^1 L$ }1 N. E. Z/ Kto setup-globals
" c9 Q. \/ L2 H: ?- E  set current-light nobody ;; just for now, since there are no lights yet' q$ k; [( m; U" d5 J( f
  set phase 0
7 c5 ~2 h8 a7 z7 u$ C  set num-cars-stopped 0
$ n& D/ d5 \0 b. Y+ j. j! r  set grid-x-inc world-width / grid-size-x' [0 Z, F' l( D; y8 }
  set grid-y-inc world-height / grid-size-y. g& S/ b7 y  }4 g, r6 l& j
6 g. O2 s9 h9 X0 m/ W- E0 [
  ;; don't make acceleration 0.1 since we could get a rounding error and end up on a patch boundary  i2 i8 i$ ?9 `  Q0 p
  set acceleration 0.099
2 N; F# n1 H4 W& bend
3 ?1 V# i; |+ y. I. \5 A" N  _2 O
0 u; k# \2 X6 Y9 b6 p;; Make the patches have appropriate colors, set up the roads and intersections agentsets,1 P0 H" I% S' y+ V# [
;; and initialize the traffic lights to one setting
  t( H# w& S; T1 `0 c: u- ~% H( Rto setup-patches* Y$ q5 O1 r  U
  ;; initialize the patch-owned variables and color the patches to a base-color
* B6 M! {+ I, f4 _7 l7 l& I  ask patches4 B4 C+ |2 @3 }5 n0 o( V& ~! B
  [/ W" b2 t2 @# _& m2 L5 X; E
    set intersection? false- x4 M! J+ L4 k8 O8 Q# h
    set auto? false* Z  ~8 L9 W1 a, l4 p! \
    set green-light-up? true# H+ E! I: h- Z4 C5 p
    set my-row -1
$ S& n7 _# g8 O9 Q# f  v    set my-column -1- ^& L6 N/ B" T2 z
    set my-phase -1+ x- ~+ K7 _9 |6 m6 ?
    set pcolor brown + 3
, f4 D8 _1 [/ u, w/ K  ]- [) D7 x8 z& S4 M; y
. h) g$ I$ v; y3 {
  ;; initialize the global variables that hold patch agentsets
4 M1 k' s" H0 g% i) p* a  set roads patches with% Y% ~. W, q/ @9 Q: \. T
    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) or! Z, r  `5 s9 n6 `! y( c
    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]
% J$ {3 f. C# d: h# l) G- @  set intersections roads with+ W, _3 }4 o$ |
    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) and
. t0 j4 ^" o! r1 C2 B    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]  O4 S9 M* Q, b# c/ t* W

% m/ ~9 h  {+ d2 b% ]' H/ A  ask roads [ set pcolor white ]# S$ M! }9 ]: b* L- c$ J
    setup-intersections, D7 V/ ^. Y% H; b! M8 u
end
3 C0 A5 _- B1 J. s其中定义道路的句子,如下所示,是什么意思啊?
- |5 n- x& D% ]/ @- U8 l* z* ] set roads patches with; J2 Z2 l/ k9 q8 @5 W
    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) or8 \1 a/ H: @. d0 w( H
    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]
5 z; m9 I7 K4 Y' \  g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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