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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。
! ?3 l9 q8 |& v% f6 V5 `netlogo自带的social science--traffic grid这一例子当中,6 m5 f- G+ ^  e
globals
$ T8 f8 e; p! V% a[
# [: }) G8 a3 }1 J, I" D# w  grid-x-inc               ;; the amount of patches in between two roads in the x direction
/ L5 x1 w/ _+ `4 s, ?( T1 j8 m1 T  grid-y-inc               ;; the amount of patches in between two roads in the y direction
, |0 j8 M6 ]5 a# U$ o  acceleration             ;; the constant that controls how much a car speeds up or slows down by if
( q6 b' b. c1 {                           ;; it is to accelerate or decelerate* j/ E4 ?" X5 z5 m& ~; m* _
  phase                    ;; keeps track of the phase+ r6 i+ d* ^) n2 D
  num-cars-stopped         ;; the number of cars that are stopped during a single pass thru the go procedure
/ Z; [  H5 w) N: k9 @7 [  current-light            ;; the currently selected light* U9 ?7 V' V2 u  d0 S! `: h( M

# w) G" W+ ^9 X" F  ;; patch agentsets9 B  e1 N5 j# e
  intersections ;; agentset containing the patches that are intersections
& d( M; A, k& I, {6 |  roads         ;; agentset containing the patches that are roads
% n0 d* ?0 k- V, P- |], h, V/ Y9 b6 @- p* A0 |7 a

9 h# j0 H  d7 v0 @0 Mturtles-own* e+ x+ e6 d0 Y' j. S( w
[
( I; H+ N8 G  w- Z! B3 V# @  speed     ;; the speed of the turtle
1 [7 }$ V  e" g. ^. i4 q  up-car?   ;; true if the turtle moves downwards and false if it moves to the right" i4 c+ [) J7 m* X7 Y
  wait-time ;; the amount of time since the last time a turtle has moved
$ [  I. q# a& z$ q- T9 Y]6 t- z% |0 V* l9 W6 F9 J
+ ?! w5 p5 c6 W1 X9 g9 t
patches-own) U+ j& Y- {4 C9 O% b/ ~
[
& D  z+ O* }  r5 ~9 ?  intersection?   ;; true if the patch is at the intersection of two roads
  P! O1 H; c' {; j! p9 @. _  green-light-up? ;; true if the green light is above the intersection.  otherwise, false.
1 [- [3 x) Y) C4 R2 H& N! h/ E                  ;; false for a non-intersection patches./ d- f) p9 R8 w) B- x
  my-row          ;; the row of the intersection counting from the upper left corner of the
) g: p, R7 x) Q; v! K. [                  ;; world.  -1 for non-intersection patches.+ Y" G7 a7 s/ u! e# L1 ^+ C: M
  my-column       ;; the column of the intersection counting from the upper left corner of the
. F' w5 \  i( F4 ^8 J& S0 Y/ i. Z                  ;; world.  -1 for non-intersection patches.5 s' p4 V* s7 k7 {" e4 v7 ?5 e/ _
  my-phase        ;; the phase for the intersection.  -1 for non-intersection patches.% ?, s+ O8 b) I3 Q' V8 M+ r
  auto?           ;; whether or not this intersection will switch automatically.
  ?# y% }" o, S- n% I; o; s                  ;; false for non-intersection patches.
& m. W+ V4 u3 Q4 s3 P% B' Y]
2 k0 `' \4 q' P: n9 [. U: P
7 e0 G0 l( m- y/ A% B" S- c* F9 i. T9 E- ~& f# c
;;;;;;;;;;;;;;;;;;;;;;
+ J  ?2 `1 W! H* I6 s& ~, j;; Setup Procedures ;;
  a" J1 R; L3 c8 ]; };;;;;;;;;;;;;;;;;;;;;;
* Q0 u; @# h8 ~, w; [  D; I* X3 T; A7 m, Z: b! f8 I+ \  e) q
;; Initialize the display by giving the global and patch variables initial values.: w% [8 Q* Y7 r* l& u. K
;; Create num-cars of turtles if there are enough road patches for one turtle to1 }8 g7 k& m  M" p$ d; R5 O; V
;; be created per road patch. Set up the plots.
( S* O8 c2 ]) nto setup
& t6 B  H  ?' V% P; T  P% R. R5 u  ca
3 z$ ]6 G6 o' L5 b6 F8 n  setup-globals5 A; ]% H5 m& V% C
- ]* M7 i+ x% V* W. v) _0 s  S# U
  ;; First we ask the patches to draw themselves and set up a few variables, m/ o( ^- }; H* V% y
  setup-patches+ N/ I% v$ J: h
  make-current one-of intersections6 R& J) s9 H, {' \2 ~# _' G  J
  label-current
/ s! p, B' Y( h1 V; }2 o5 x; m
9 e7 i" ?- |9 l  set-default-shape turtles "car"
6 p( E1 P6 U. \; Z3 E  m5 f$ v# c) m* h; k
  if (num-cars > count roads)! }6 B# }1 D  P7 q
  [
2 R9 ^( L0 _$ M9 S+ s9 J    user-message (word "There are too many cars for the amount of "6 w, X+ @' C0 Z' P
                       "road.  Either increase the amount of roads "" a/ ^6 ~+ V) C/ g! b1 g8 x" c) j% ?- I
                       "by increasing the GRID-SIZE-X or "% J9 i, S1 _9 B4 \8 r
                       "GRID-SIZE-Y sliders, or decrease the "7 \3 e: {5 n1 ~6 T" [% L
                       "number of cars by lowering the NUMBER slider.\n"1 x+ L3 V7 t4 g4 F/ N
                       "The setup has stopped.")6 j2 U5 n8 b7 d5 g# p
    stop4 b$ U8 ?/ t: O' e
  ]" y4 o. ]( [6 X

1 i6 I8 l6 ~9 L8 E) h  ;; Now create the turtles and have each created turtle call the functions setup-cars and set-car-color2 @* f  H" t; l0 A8 F; W6 y
  crt num-cars
( Z# m( Z- A4 p, ]2 s' k, O  [6 c" z( ^# E9 S
    setup-cars9 ?; E3 M8 t* H' x
    set-car-color7 W; V# E. H8 s  j3 r: g" G0 \
    record-data
+ `  r3 p) }; c9 p  M8 d. N  ]
2 @% x# L, t/ x  E
" t) e4 q3 h/ c) |/ l0 h  ;; give the turtles an initial speed
( S3 j$ b2 }( J- M2 f- b  ask turtles [ set-car-speed ]. w$ D: [5 c2 s* D+ U  o0 q# s6 _

: w! V7 @! p& ~. n) F6 U0 Y8 N+ |  reset-ticks
' N! N% o8 A; @, Uend
* M) n5 M- T* d) x# E3 h9 w
* M* n2 V7 Q( M+ X% ]  P% J;; Initialize the global variables to appropriate values9 e) T+ Q& u! ]
to setup-globals8 }. Y, o7 ?' M9 D: S
  set current-light nobody ;; just for now, since there are no lights yet
# i4 J. @" T$ d- N; u  set phase 0
& V, w4 e" F% ]/ M( s5 C% @3 \4 C  set num-cars-stopped 0% g; X: i( ~4 \) b0 l6 u' J, c- u  U
  set grid-x-inc world-width / grid-size-x5 g  z1 Q, a% V( G% P
  set grid-y-inc world-height / grid-size-y
: c& z+ O+ P. H9 R2 V: o: `# v4 I+ |$ C
  ;; don't make acceleration 0.1 since we could get a rounding error and end up on a patch boundary; t, Q. Q% `  t$ y/ Y
  set acceleration 0.099- K! l6 E5 r0 D
end: M! K. Z! J- D9 I& T7 R- Q
6 b$ W, j6 N" }, f3 o
;; Make the patches have appropriate colors, set up the roads and intersections agentsets,9 l0 K+ L9 Z7 b/ W
;; and initialize the traffic lights to one setting
- I% S  Q6 `2 qto setup-patches+ ~* N) q, `$ ^' Y* o
  ;; initialize the patch-owned variables and color the patches to a base-color7 z2 V& D; F, r0 t0 q
  ask patches
/ z( R* M" ^2 Z9 ?" U  [! J% I4 r5 r6 |+ X  ~  H: B0 Z$ v, ]
    set intersection? false
! ?" m4 K& U. l) ?4 H( |" Q, }0 k    set auto? false4 S$ C/ M  H/ C- b( A0 \! R
    set green-light-up? true
, M& {9 c0 a- g0 |0 q    set my-row -1
( d0 Q$ X3 F; c; O/ P  j( t! k    set my-column -10 g$ Y: \( X' }$ g
    set my-phase -1; F  ~, e1 F7 s7 K4 C
    set pcolor brown + 3
" [  @! ~% ~0 ^' Z  ]+ T6 u+ T3 {' T, U6 c/ q/ j

7 J8 I% i8 D8 E# i5 A  ;; initialize the global variables that hold patch agentsets
" v( U" L$ [/ L" I- a  set roads patches with
% g! d( X' \: a    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) or/ G# S+ {1 E* K: |! ^$ q" y& i4 n
    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]
* c; L  B) L9 J! ?, T  set intersections roads with
% j6 E2 F& Y0 U' ]" m9 b/ j8 ?! Y    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) and  r& E  |% y; l: Y
    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]
5 z8 A* J6 C$ q0 l' E/ ]4 \* ?; I- R8 {
  ask roads [ set pcolor white ]! r% l* v6 o, B; g
    setup-intersections
. G+ O7 O( X1 g3 D( _( \end
8 }7 q' n' e8 N其中定义道路的句子,如下所示,是什么意思啊?
2 w6 {: h3 k$ t% S" I1 H set roads patches with& W+ E  s: G8 w  n
    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) or
* Z5 v- ?0 x: B: t- \5 c+ B    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]! r/ ]. k, Z  e0 O
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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