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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。6 n) _+ ^2 s) o) G+ u
netlogo自带的social science--traffic grid这一例子当中,
: L$ [7 J9 z% jglobals
8 u' B- ?8 U; Z5 c[5 |4 h& X) d/ J" G; S$ ?
  grid-x-inc               ;; the amount of patches in between two roads in the x direction
. j' J+ l  N* c3 q& i- \  grid-y-inc               ;; the amount of patches in between two roads in the y direction
; D. T, T. }- I$ N0 b  acceleration             ;; the constant that controls how much a car speeds up or slows down by if8 d! c, d# |* l2 ~6 B- B
                           ;; it is to accelerate or decelerate
+ O% t, f. `2 U* R) ]  phase                    ;; keeps track of the phase
9 E' k: Q  ?! B9 U  num-cars-stopped         ;; the number of cars that are stopped during a single pass thru the go procedure
* v; L0 t9 Q, u, `1 S  current-light            ;; the currently selected light
$ m" j$ s" W: m/ {+ ~* g  W, [4 Y- Q, X5 N8 b3 {
  ;; patch agentsets
7 |! J0 H- m7 ?# {9 S  intersections ;; agentset containing the patches that are intersections
- b  L2 x7 Z) L$ Z5 [, l: y- j% e: }  roads         ;; agentset containing the patches that are roads
' O4 J+ P  N" [! g]
$ @1 d- F  R7 c9 o) ]# T4 v, S1 H( D* R
turtles-own
1 j- R8 f" E& z8 |[
0 w& L2 y  V  z7 q+ ~( r  speed     ;; the speed of the turtle6 X3 w8 h/ v3 P) V
  up-car?   ;; true if the turtle moves downwards and false if it moves to the right
! I0 Z; u3 \8 O$ R% R: \" z" @; f; v  wait-time ;; the amount of time since the last time a turtle has moved
$ f" I' T; B7 A9 a2 i! ]]4 S& r  l( o3 ^3 y1 e

/ D, P0 a% y4 W. ?$ @patches-own
% I; X/ \1 t4 H# k! e9 ~, X. L[
0 _3 R, I" i+ m  intersection?   ;; true if the patch is at the intersection of two roads4 [% u, g7 o* J$ X& w
  green-light-up? ;; true if the green light is above the intersection.  otherwise, false.
' H* j4 A- g+ X" T2 z: r4 O: W                  ;; false for a non-intersection patches.
5 b) s+ T6 t0 c% A. m  my-row          ;; the row of the intersection counting from the upper left corner of the
9 Z9 @* f8 z0 y( r# Q3 F: V                  ;; world.  -1 for non-intersection patches.: W1 B7 x, _3 Y4 Q  ?
  my-column       ;; the column of the intersection counting from the upper left corner of the
: p% g3 k. w2 ~" J8 l& a/ R$ {                  ;; world.  -1 for non-intersection patches.
# X; }) o1 c! Y7 \1 L6 @( _  my-phase        ;; the phase for the intersection.  -1 for non-intersection patches.% _- H! X8 e+ n) F. l, R( E
  auto?           ;; whether or not this intersection will switch automatically.
- S; l/ k6 {& Z' f) P, c                  ;; false for non-intersection patches.
9 R4 Z8 g* K: d]
4 \# h7 X/ U; v
5 H* c9 F$ Z) u9 u" h; A' u" s" h7 H+ ^8 n# V- T: \
;;;;;;;;;;;;;;;;;;;;;;
3 F5 m7 ~* k, c) @; J$ F" H;; Setup Procedures ;;
, D0 o# f* R, p- u;;;;;;;;;;;;;;;;;;;;;;
$ ^% \  X) v# }! u6 ~! Z/ e# b9 T6 Q6 F1 Z
;; Initialize the display by giving the global and patch variables initial values.
; \2 w2 Q/ q* G;; Create num-cars of turtles if there are enough road patches for one turtle to" O* h9 ]2 q! D6 O4 z! G# X7 Z
;; be created per road patch. Set up the plots.
! d  J3 S0 [3 h4 Yto setup- D# j3 Y! p- i4 E8 C& e4 b6 ~! X
  ca; Y; i6 t# i" H2 F9 p% b& o
  setup-globals- t6 ^' S% n. F3 ?

; \+ o. g8 Y; R: e6 R% {  ;; First we ask the patches to draw themselves and set up a few variables
9 b/ C0 d( E1 J) D: [  setup-patches' F" l' b  v# Z0 i6 H
  make-current one-of intersections/ n- V) l7 n* O' ?4 |+ T9 g  I
  label-current
% p  K9 u- w( L4 r. Z; }( g3 [$ z  N* j& j$ e6 U
  set-default-shape turtles "car"$ k) R- j# V2 X4 |+ Q  @( p

! [) u' M! c- g  v4 D% O  if (num-cars > count roads)
/ i/ P) E; y0 B" N! i9 g2 @7 l  [; E7 W8 k* L, Z; }" h
    user-message (word "There are too many cars for the amount of "" G6 A* o1 ^% ~* {- p- N
                       "road.  Either increase the amount of roads "
! ^  Z" P1 r: h4 Q+ S                       "by increasing the GRID-SIZE-X or "# W6 X) n- x. B& N0 _% c
                       "GRID-SIZE-Y sliders, or decrease the "
" E. n7 k" \  N' ^, X- f                       "number of cars by lowering the NUMBER slider.\n"
+ O) h4 T' ?4 V( C9 J  T; }- O                       "The setup has stopped.")
3 k* r' }# L# j    stop3 _1 |6 @4 E7 \5 Q0 I
  ]  a, ]& U( z/ i5 ?& _+ u8 ]9 i

8 Z$ @) _0 b# J% i, T$ M3 O3 C  ;; Now create the turtles and have each created turtle call the functions setup-cars and set-car-color" ?+ E5 r) v) T) j
  crt num-cars) K$ `2 J/ A! F  |) q% V' F" L
  [
; e8 h6 F4 C4 [- C    setup-cars" L- r( e( T4 m: P: d6 p( V
    set-car-color
9 Q/ m! S& S; Z* D7 U! _    record-data0 Z' q" o$ @2 s1 p3 x
  ]* D  @$ K3 J  X  g7 B
+ h% S. ]9 I* {# a3 s4 M. y
  ;; give the turtles an initial speed
& w/ \9 r4 z2 L& }( K# C  ask turtles [ set-car-speed ]( i' x7 b4 X4 \& A7 L: t

7 O2 w' T9 I: g: L( X  reset-ticks
3 B6 J: J: m+ d  y/ w3 t- t4 Bend3 n7 s3 w) k( S. X2 S

; h3 P" u# d% u8 {;; Initialize the global variables to appropriate values* S( z" U6 T" ]1 n& X1 }
to setup-globals, |% N; |6 E6 l& @# [
  set current-light nobody ;; just for now, since there are no lights yet4 f% M7 ?; V& m. j' |+ Y8 I
  set phase 09 O' L8 Z; q8 i) Q8 t# L2 W
  set num-cars-stopped 02 K% H% |+ e' o* \7 I& X! E: o* Y. d
  set grid-x-inc world-width / grid-size-x
4 k: f( W2 ~- G/ [  set grid-y-inc world-height / grid-size-y' C7 t6 c+ h# I
9 [' ?# t- z/ t2 e6 a$ U
  ;; don't make acceleration 0.1 since we could get a rounding error and end up on a patch boundary. V" m( s' r+ h9 U
  set acceleration 0.099
" C' z8 c' ?0 k( u( x! d9 T1 Dend
$ J. P3 u0 D" ]+ ~, c+ L2 [6 L* \0 O
;; Make the patches have appropriate colors, set up the roads and intersections agentsets,
5 P2 z5 T9 @; `8 G! b: F;; and initialize the traffic lights to one setting
+ R( ?# ^# d- ?8 b4 n& [to setup-patches
. a" Y0 {- m! R8 D: o9 Z' d7 i3 [/ E  ;; initialize the patch-owned variables and color the patches to a base-color
& h  ^! {4 l1 G' @6 V3 I  ask patches& s- w( e# G2 ^
  [
: e" ^' `  j) {& g    set intersection? false
0 `9 X8 D2 {. Y    set auto? false
7 s0 D6 I) S% g- }8 a) ~* H9 c    set green-light-up? true+ {2 {/ [7 `0 \& z9 y$ f( h2 p
    set my-row -1
) M+ a: L9 x! h# ]2 T7 D$ m, g; ^4 R    set my-column -1, c& [, }3 g7 ~; Y
    set my-phase -1, X/ w$ S- O9 `; t" w
    set pcolor brown + 3* Q; h0 c% b4 X
  ], s, ~: p8 j4 ^+ U4 }

' D; h' f& k9 \* r  ;; initialize the global variables that hold patch agentsets: L2 y; _! N7 W- w
  set roads patches with$ P, t$ Y# Q- V9 u4 K1 x. p) v
    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) or( S. O* G% l( B) N7 ]5 H
    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]3 y% i2 `7 I$ |, b3 W
  set intersections roads with
; W) Z8 m+ Y$ o: i! q    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) and" o$ F/ \! _  |0 @  V0 n
    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]& _: l% P1 r4 t( C

. M  b$ T' i5 c5 j3 }  ask roads [ set pcolor white ]% K& g2 R3 T: A
    setup-intersections/ K+ ~$ d2 k& u. {3 F8 n; J- d
end
& l+ l/ U: X3 ]# }其中定义道路的句子,如下所示,是什么意思啊?- t0 ~6 d) s# F6 }8 \+ ?+ ~
set roads patches with( w! s6 D/ _# `7 {8 V
    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) or2 z1 H1 H! J5 `9 d5 J& F  m0 L+ A
    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]- J& i6 S8 l: q# p8 M
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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