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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。9 h& F  f7 s8 G2 D% i
netlogo自带的social science--traffic grid这一例子当中,! p1 p5 ^" P! Q. e* y  T
globals
, d$ ^# n5 X3 O$ {[
7 B$ J* R8 K6 @! q9 L& x  grid-x-inc               ;; the amount of patches in between two roads in the x direction
0 j7 E& a7 l; m! g6 v% @  l" }- K  grid-y-inc               ;; the amount of patches in between two roads in the y direction# W" C2 q6 o5 h5 @6 M2 m3 v
  acceleration             ;; the constant that controls how much a car speeds up or slows down by if( c( p; `; q6 @0 h+ W" Y2 t$ h# R
                           ;; it is to accelerate or decelerate% e, Y, K  k! i* {
  phase                    ;; keeps track of the phase
, z: e. e1 t1 v  ]4 `  E3 M# P  num-cars-stopped         ;; the number of cars that are stopped during a single pass thru the go procedure2 A& P/ @# t: l1 C( o& @4 l
  current-light            ;; the currently selected light
( x; F9 L4 U1 e* r+ Y6 U
* b8 y) I8 m9 i- N  ;; patch agentsets
3 l2 F1 M6 [2 I8 D- ^1 L  intersections ;; agentset containing the patches that are intersections9 c+ N- v% _2 X1 _  v! A! z9 c
  roads         ;; agentset containing the patches that are roads  J$ y2 V5 ]& f
]
  w' ?! O  h8 `: ~- |+ ?7 x3 r0 I0 Z5 b+ I5 h4 G4 q7 U5 a8 Y& P
turtles-own- C0 l7 v6 m/ `% G2 n2 E
[; a; M* y- a1 R$ w$ t4 E9 M- \
  speed     ;; the speed of the turtle
! g! D3 s5 C  [# f* I  up-car?   ;; true if the turtle moves downwards and false if it moves to the right9 [% _5 J/ n1 n4 i- ?$ d
  wait-time ;; the amount of time since the last time a turtle has moved
7 J+ c" e* B& M: v& X$ |]
& o0 U5 `; u( M! L* X' D9 U4 o2 p4 l, j4 \. }
patches-own
* h! |! A4 b8 @( S[
! \6 H0 E: `: }, z  intersection?   ;; true if the patch is at the intersection of two roads1 f* M) ^5 l" X+ q
  green-light-up? ;; true if the green light is above the intersection.  otherwise, false.
% b! D" x  n" J% z( e; C                  ;; false for a non-intersection patches.. T3 G: ]7 k# h1 s' Y5 S
  my-row          ;; the row of the intersection counting from the upper left corner of the
/ ~5 Y9 u) z0 t' c2 I6 e                  ;; world.  -1 for non-intersection patches.
4 a( L, S$ i! t8 J( G0 }  my-column       ;; the column of the intersection counting from the upper left corner of the
# R& a3 R* O# ]5 W! i% O1 F" F                  ;; world.  -1 for non-intersection patches.
9 E4 t. |0 `. L; n  my-phase        ;; the phase for the intersection.  -1 for non-intersection patches.
2 d& H& m8 \( y8 q  auto?           ;; whether or not this intersection will switch automatically.
: {: `7 j& N* V0 m                  ;; false for non-intersection patches.' N6 v/ v9 ]4 Y9 l/ |( ]+ I
]9 f& e3 r9 B. t

9 _; [9 J7 h( W9 T% j$ Z5 h7 Z% |: a% \) w3 m
;;;;;;;;;;;;;;;;;;;;;;
8 u- O# x0 X( p$ C3 w, P6 h9 T- ~;; Setup Procedures ;;
$ c1 j2 E) @+ w5 N: G' z8 E;;;;;;;;;;;;;;;;;;;;;;& y3 v* s' J" `' u5 e

. U+ W: X' {" O2 H" W;; Initialize the display by giving the global and patch variables initial values.
6 l. R6 k1 S8 v# o, C& w;; Create num-cars of turtles if there are enough road patches for one turtle to3 w* G/ T( S. _7 J! s
;; be created per road patch. Set up the plots.
) F, t" C/ q4 ]: u7 Eto setup
  |5 `8 c% w/ n  ca# Q0 ~* @  x- W7 r1 ?' j3 E* R
  setup-globals
6 @3 D& n0 P8 |6 t" H" v( q9 Z' i0 I9 n2 ]1 P) U/ ]
  ;; First we ask the patches to draw themselves and set up a few variables- u! J7 L& ]( R% C8 c  Y
  setup-patches
8 x$ k/ t, T5 h  make-current one-of intersections
: {; o9 M/ T& r& q  label-current" m5 K$ [" o" p2 @) N

& Y. j0 \8 e( o! v+ k  set-default-shape turtles "car"  D  c2 X# Z  T- e& ^+ b
  a2 |5 T, ~; x
  if (num-cars > count roads)
7 d( k* r- {1 t- I1 \  [
0 w: ?2 v- c' G    user-message (word "There are too many cars for the amount of "
1 `- d4 {+ k+ d# p3 z                       "road.  Either increase the amount of roads "0 G1 t* B( }; F% v; }
                       "by increasing the GRID-SIZE-X or "5 @: A" E4 p4 v
                       "GRID-SIZE-Y sliders, or decrease the "
/ t* w, s- Z0 ?. w  p; ^# m+ Q( y                       "number of cars by lowering the NUMBER slider.\n"
4 R' d& s, m( E                       "The setup has stopped.")1 w; z" x* O" O
    stop
: a2 [0 d9 l8 E5 X& q$ {* E5 V/ \  ]; c3 g# d# Q2 {6 T5 ]' u* [% Q
. ?  q  E4 D' M
  ;; Now create the turtles and have each created turtle call the functions setup-cars and set-car-color
2 i, l" S% }7 G  e) o1 z6 O: A2 f  crt num-cars
1 e# d( Z! X9 F+ W/ _7 j( X* ~# T  [" }* ?( t; _( f$ X# v+ s- T/ Y
    setup-cars0 u8 y8 X; n# o% E/ w
    set-car-color
8 o* ^2 \4 \8 J, G3 _' B$ J    record-data
( [4 M) ^# a1 P; C$ C9 x' O. z( o  ]
' Y- \/ j/ z& a3 ^2 i, z# H* W- j: Z5 p& c! K# o) e6 r
  ;; give the turtles an initial speed
6 m" B2 c% U3 \# U" ~8 [( a  ask turtles [ set-car-speed ]8 C! [1 A( o) W
) ^, a7 N0 ^5 y* S* R
  reset-ticks
' e3 X' O# T3 x9 w- K8 kend! R2 j# J( i; i$ t
1 o/ y: r* V% M1 C
;; Initialize the global variables to appropriate values9 ]' L2 [# c5 @1 I" b3 n3 o$ M" D! l
to setup-globals' f6 n0 S% D2 I* H! p
  set current-light nobody ;; just for now, since there are no lights yet. ?0 }. J; [! M
  set phase 0
( _" z& i# \- Q5 V( A  ?2 }% z  set num-cars-stopped 0
! `6 `0 r' t* E1 v% U3 D3 u  set grid-x-inc world-width / grid-size-x
1 V3 |& O4 V* q9 h' M  set grid-y-inc world-height / grid-size-y
& z- ]; C  f8 e7 h
$ X: }0 }: b8 O( s; y) |  ;; don't make acceleration 0.1 since we could get a rounding error and end up on a patch boundary
: \. `+ w% f) W5 E7 Q. ~* V) A: Q  set acceleration 0.099$ H2 Z' B: g) `
end7 ?! r& @/ a2 J# e3 k( J

/ u) W$ B6 G# U1 y8 M;; Make the patches have appropriate colors, set up the roads and intersections agentsets,
* Z3 X; i) @3 y) _4 X9 R;; and initialize the traffic lights to one setting, b& Y8 U6 |9 H2 f; p' B
to setup-patches
3 v+ M! F; q, u5 \/ ]  ;; initialize the patch-owned variables and color the patches to a base-color/ q: C& d( Q3 Q+ H+ y6 R
  ask patches# D. O% J! M  i6 p7 }  e+ M- U
  [
6 O2 K+ J- A5 A* q/ W' L- n    set intersection? false7 U7 ~# J* x# B' q2 g
    set auto? false
% `  C0 ~5 d9 k( {    set green-light-up? true
/ e' G. h/ V5 V: }: d5 N    set my-row -19 ^+ J  N- U/ S) i9 X
    set my-column -1
- m- }2 g' W% I# ~    set my-phase -12 {  K! {1 d& O* ~, g& k; V
    set pcolor brown + 3" ]2 `+ i2 u% i4 B/ q
  ]
2 |' J# Y: x' y$ E- W; M5 Y1 T% |" d8 e" a$ S6 ]
  ;; initialize the global variables that hold patch agentsets
. t+ j3 g+ `. A1 s; z  set roads patches with
  w- n0 I# R' B# J; \+ T; q    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) or
+ G8 ]  u9 I' ?3 U6 Q" Z$ W+ V+ n    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]
1 \! R, s- }( R( `  set intersections roads with5 I) R) K7 i4 B; x2 L* |1 N) l! x, _
    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) and3 P6 c- N$ ]- b/ @! ^- r# A
    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]& P; W0 y: N7 H

0 H( @3 s; C% F  Y  ask roads [ set pcolor white ]
% s" H" Q% e* j& e    setup-intersections( w4 M# D6 B, `5 i, F
end
$ v; @7 j& x- Z% S其中定义道路的句子,如下所示,是什么意思啊?
% K9 l  Q; s4 U( A set roads patches with" e& Q. S. I/ D( h' ^
    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) or, {* s0 P4 b# B$ |
    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]1 O0 N5 V6 \5 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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