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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。. N+ V! A( R& ]9 b2 ~* b
netlogo自带的social science--traffic grid这一例子当中,
# l8 E5 k8 K7 C& D* l. F  A4 |0 Y# Fglobals
& p& P4 R7 ~" g% {7 c" z- O[% S9 x' D) p* K
  grid-x-inc               ;; the amount of patches in between two roads in the x direction% Y* n6 g9 N! u8 ^& {9 \+ A% b/ e
  grid-y-inc               ;; the amount of patches in between two roads in the y direction+ t" X& w4 c3 K* i( ]7 U0 L2 c/ p, ~
  acceleration             ;; the constant that controls how much a car speeds up or slows down by if
9 Y+ n: a4 E+ K/ T+ u- \3 ?7 x# v7 H7 U                           ;; it is to accelerate or decelerate( D% V$ y% W3 A' A8 g" h+ ]
  phase                    ;; keeps track of the phase4 |5 j( d- `: t- [* K- ~' Y
  num-cars-stopped         ;; the number of cars that are stopped during a single pass thru the go procedure7 I* Y4 k9 |& T' z9 H3 \; q1 h
  current-light            ;; the currently selected light
5 p; q! C- b9 l1 d) P; e
- U6 B' _8 y* f  ;; patch agentsets$ A! P, I% B4 t0 |& E( p; s1 U
  intersections ;; agentset containing the patches that are intersections: Q6 N1 J7 C" x7 _* [: Q
  roads         ;; agentset containing the patches that are roads
+ |! t6 e1 q5 J/ W5 i]' s9 `8 L% q' ^$ e9 m2 {
3 b3 x/ h6 [0 G1 U' k- ^! Z
turtles-own$ |( w" G. F" J6 s. ~
[
; m0 f! r" c* j. x  speed     ;; the speed of the turtle
8 V( }1 _+ ?% _& q5 E+ }  up-car?   ;; true if the turtle moves downwards and false if it moves to the right
- u. @, B5 X; J. r: p$ x  wait-time ;; the amount of time since the last time a turtle has moved5 n$ i6 T; ]0 O
]/ F  O9 I5 e/ H' E+ ]: q: _* p1 b- U
- M" |2 P* |  V- b
patches-own
( R8 u& n4 W0 f# ?  l[
0 a$ U" K" D9 q2 |  intersection?   ;; true if the patch is at the intersection of two roads, l! B/ d+ l- p' \& w
  green-light-up? ;; true if the green light is above the intersection.  otherwise, false.
% C. f( U3 [  p( k$ J7 E, _                  ;; false for a non-intersection patches.0 v1 q$ N9 O. Y( c% _. Y
  my-row          ;; the row of the intersection counting from the upper left corner of the- g  g+ T% H8 s7 W9 S, ^
                  ;; world.  -1 for non-intersection patches.- P) Q( s3 c3 t& p! n3 e4 {
  my-column       ;; the column of the intersection counting from the upper left corner of the: a% k, k! Z: F" g5 ?4 }
                  ;; world.  -1 for non-intersection patches.5 H5 E  Q1 g) i1 L& _
  my-phase        ;; the phase for the intersection.  -1 for non-intersection patches.  w3 L" M) d7 q4 r
  auto?           ;; whether or not this intersection will switch automatically.' s4 D% }* [$ D0 I) \- j
                  ;; false for non-intersection patches.
0 U( w# `1 e' F& C: R: t]8 J; ]( b/ G$ j# T& `
$ g: d0 Y& E, a0 B1 ]
6 I- E+ _  T# Y: x4 G! b% [
;;;;;;;;;;;;;;;;;;;;;;/ ?  _) x. c  d- t, |/ z
;; Setup Procedures ;;
: w! W. [8 c2 ?; `;;;;;;;;;;;;;;;;;;;;;;
6 |8 R+ D8 W8 t# \- d+ L# P
5 j$ Y) H2 r( D7 ]2 t;; Initialize the display by giving the global and patch variables initial values.
+ s6 c/ d; K1 [7 r;; Create num-cars of turtles if there are enough road patches for one turtle to
' A  T) T& j8 z0 r2 C! c% v;; be created per road patch. Set up the plots.! P8 C9 @* V9 S& ~1 J) U
to setup% K% r* w# y. P; L0 Q8 C/ V* u
  ca, v. V+ O" t  Q8 b4 D, g
  setup-globals, [# ^5 P2 w& d1 P
+ U3 L6 K$ e4 d7 I4 r! J! D
  ;; First we ask the patches to draw themselves and set up a few variables
: g8 M* D. b4 Q: N/ W% O0 V  setup-patches
, Y: S' |/ @9 m# V6 v  F  make-current one-of intersections; Z5 Z# H% e3 v3 F( \% R
  label-current
) F; u4 B5 G" A8 L1 T( w! T2 }! k+ p
  set-default-shape turtles "car"
0 M) s5 z4 O! \6 i" j9 h5 X- e- L+ z
0 P" g) ?, E% q8 d" y* B( d+ X  if (num-cars > count roads)6 v3 |7 H7 I/ B) H+ u
  [9 t5 F5 O8 M4 M5 Y1 \
    user-message (word "There are too many cars for the amount of "
2 B5 c, Y1 R2 v  a5 I% F                       "road.  Either increase the amount of roads "2 Y4 ^+ o& Z: y7 Z
                       "by increasing the GRID-SIZE-X or "8 B+ P; b6 _' x6 O2 ^
                       "GRID-SIZE-Y sliders, or decrease the "$ E! f, w- ]- `, l1 R9 r
                       "number of cars by lowering the NUMBER slider.\n"+ |; |$ t0 {- }; t( l% A3 O
                       "The setup has stopped.")
! m1 T' R; G0 x, e5 l    stop& T. C! u/ U4 r9 s2 z
  ]
+ A4 ?# A* V% a! b5 a7 t
! Z( R* ^! ?- I2 Q6 p1 d  ;; Now create the turtles and have each created turtle call the functions setup-cars and set-car-color
6 e8 S. R( ?! M4 n2 Z% y) [; _  crt num-cars
* C, |) f8 w/ _9 k7 K  [2 Y7 C, q8 ~0 Z% m
    setup-cars
8 b  E$ V8 B" K1 _  G+ l    set-car-color
  h  t! r6 g7 e7 Y8 C) b    record-data
5 K, n7 V! E8 |5 D+ C  ]; P/ @! `0 o7 ~& [5 v; C

: m) U& s7 e5 m- y$ E  ;; give the turtles an initial speed1 \) w/ r1 r! {/ ~8 W3 @* C2 J
  ask turtles [ set-car-speed ]
7 W* L8 w! I- \, w4 K9 \* P# L
+ g- t2 b2 n4 @$ T# v  C  L  reset-ticks' x! b) }" v% K# |* f
end
& r+ N8 p! N8 s9 O+ T5 K0 \9 ~! V( L' i4 M& B" c
;; Initialize the global variables to appropriate values' I% O7 E6 ]3 y0 X* Z# H
to setup-globals8 F' I# x1 T" j- A  t
  set current-light nobody ;; just for now, since there are no lights yet
* k- b. P) P- ?& x. H5 V  set phase 0% ]  b1 j& v/ a9 E
  set num-cars-stopped 0
& ?& l9 q) I2 w3 R# l$ A8 B  set grid-x-inc world-width / grid-size-x/ [$ Q  \9 b1 w2 T
  set grid-y-inc world-height / grid-size-y
) A2 @3 s) S7 U/ E
) z% W/ T! f0 T. h" v1 U  ;; don't make acceleration 0.1 since we could get a rounding error and end up on a patch boundary
+ u9 V  d: d4 x7 Y3 Y# ?  set acceleration 0.099
, u* z' c! e; t4 \6 ?+ gend
$ h1 V- Y. W" O+ f" @
5 P6 }7 A& U( w( V;; Make the patches have appropriate colors, set up the roads and intersections agentsets,
# ^7 K7 q9 A  D1 B& @9 N5 x0 h;; and initialize the traffic lights to one setting! C( n0 m0 H! c% e
to setup-patches
: E! N# L. \8 k% H: L  ;; initialize the patch-owned variables and color the patches to a base-color
) c" F5 q- p9 m9 i: h' K0 T  ask patches
; P4 g1 E; f: f: U5 L' l3 w  [' e  B) {4 U" @
    set intersection? false
+ m6 \: a# M1 K    set auto? false
! X9 H/ l& C$ |! u1 D, U; N: o) c    set green-light-up? true
& Y# d! r& S8 l2 ~- b    set my-row -1# i$ c+ J8 @. q) v" v
    set my-column -1
+ g( f; s4 f2 t9 M; u9 W% }7 k    set my-phase -1
4 h2 B" W5 R5 L9 p& E, Y" h    set pcolor brown + 3
8 N& Z# A9 b5 J5 i( m/ z; k  ]5 C# L0 L) `# ~" g3 ~
8 m- T! W2 B) s, a1 I' ]8 z
  ;; initialize the global variables that hold patch agentsets
$ q7 q  p- U6 o6 n  set roads patches with
" G1 W7 `% f9 X  n4 _" v; U    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) or3 H! i, |: B/ Y) v$ }9 P) A* }1 G
    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]
) k* e& P; }' X3 l8 v' s  set intersections roads with
( E0 {! J1 n6 L7 U4 k4 s, u# g+ f    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) and  R& j4 F* m+ S8 J  [4 V6 i
    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]9 K( b( P9 j% }' R! X
! [$ Z3 Q  F- X' {% H  M. Y
  ask roads [ set pcolor white ]
& P/ C9 H' ^1 G  K) {6 j    setup-intersections
( ^1 H) E1 u: O  j5 t: kend! W* S# }1 z% n! r% j6 g
其中定义道路的句子,如下所示,是什么意思啊?& X1 v' ?/ z- U$ P2 x5 @8 H" ~
set roads patches with
, K) t4 Z! E3 l: f    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) or9 G9 L. Z! ^# |# r' c. `- W, ~
    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]
1 J. E% }, m/ [8 H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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