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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。. b1 y0 b5 ~! h$ s! _9 G
netlogo自带的social science--traffic grid这一例子当中,! F* D3 [# v; J, n1 _) T
globals* @! a$ {) X9 J9 r8 ?
[
4 a  I- p- K% u* o6 S/ ^  grid-x-inc               ;; the amount of patches in between two roads in the x direction
- c) }1 c8 ^4 \7 d8 s9 c) I+ k  grid-y-inc               ;; the amount of patches in between two roads in the y direction1 n. r# Q, f/ g: S2 w8 b- v. {
  acceleration             ;; the constant that controls how much a car speeds up or slows down by if
; }# Z) a8 T  T- l                           ;; it is to accelerate or decelerate% p( O  m0 W/ T; L
  phase                    ;; keeps track of the phase( Z, ]6 L: V- {5 {/ D
  num-cars-stopped         ;; the number of cars that are stopped during a single pass thru the go procedure+ x9 M! ^! ?  [: w
  current-light            ;; the currently selected light
& r2 r, N* ?. l0 H# \
! D9 e: F9 @1 B2 Z' G  ;; patch agentsets
% [1 R1 C* N2 h& d7 c  intersections ;; agentset containing the patches that are intersections+ C! o, K, v  l
  roads         ;; agentset containing the patches that are roads
9 H. m/ r+ O; r9 a1 q]
4 K2 G! r1 N, h$ f( [! |& e' R, I5 V6 I/ V9 ?! {$ X
turtles-own) O2 W% [# N! L# ?0 D
[
9 {( Z: _9 X& P9 K! w- f3 o5 L2 K  speed     ;; the speed of the turtle* k8 F8 h+ @$ c1 U, [; v
  up-car?   ;; true if the turtle moves downwards and false if it moves to the right
  h  w, {; e3 {. u% Z) |/ B  wait-time ;; the amount of time since the last time a turtle has moved# X% l# A, G# V& D& e" S
]; e2 l5 o( N) ]% W" h
, X6 m" n+ z- [$ [
patches-own  u7 g& y. R) ^
[1 w( P' c  Q; P0 D- M# ?
  intersection?   ;; true if the patch is at the intersection of two roads# f, c8 D" x- [7 M  e0 v
  green-light-up? ;; true if the green light is above the intersection.  otherwise, false.
7 Z/ N2 ?3 R3 Y2 v, K$ e" U0 J7 ?                  ;; false for a non-intersection patches.& o% ~( m% i% J) @
  my-row          ;; the row of the intersection counting from the upper left corner of the* K6 z7 e/ H; {# `, z- W' v
                  ;; world.  -1 for non-intersection patches.
& r6 e5 \/ h8 v& r3 O  my-column       ;; the column of the intersection counting from the upper left corner of the
0 D% u( j0 a/ U                  ;; world.  -1 for non-intersection patches.
6 i$ x1 l# Y2 J( V  my-phase        ;; the phase for the intersection.  -1 for non-intersection patches.
( k2 Z8 T( r/ ^# @5 z* ^  auto?           ;; whether or not this intersection will switch automatically.
& S( m5 I0 g4 w0 i6 H                  ;; false for non-intersection patches.
" \2 f$ G7 V' q' s: i! G]# N4 d" M7 |( P: R1 B9 s! I
8 G: h# W8 u, i/ @+ ^2 m( |' l

" \: A9 ^% c/ C;;;;;;;;;;;;;;;;;;;;;;
4 K( i/ `+ ~1 L4 E4 ?/ B) w+ _4 t;; Setup Procedures ;;
6 D( L$ _0 k! J! Z9 w, _3 T6 y;;;;;;;;;;;;;;;;;;;;;;
9 t' N  w! F: |
, D' o- [7 Z% A9 `0 T;; Initialize the display by giving the global and patch variables initial values.
- g8 v. |% q- \0 L/ o;; Create num-cars of turtles if there are enough road patches for one turtle to
% e' D+ u) w  ]6 T6 b. _: \! u4 j;; be created per road patch. Set up the plots.; r# W% H" ?5 h- E" L
to setup4 G0 Y  `4 P! h. m" x$ |6 B% C/ }
  ca6 s# I7 A. x6 Z- b% v7 \; Y  @
  setup-globals
/ S4 _. F% j- ^+ `, }- ^( A8 M- c8 ~9 {
  ;; First we ask the patches to draw themselves and set up a few variables
( v) Y  q8 u( i" F% c. b% e  setup-patches
3 ~6 f& K1 P, l, \4 w3 n* [  make-current one-of intersections
8 e# j( n% Y$ L. \. \  label-current# n% i! n- j7 T' z) Q. Q
% `$ Y3 a9 |2 I
  set-default-shape turtles "car"
$ {. B1 }2 h" o& h% Z/ N/ V, J: C! J5 s
  if (num-cars > count roads)
5 F( |" ]% V$ D  J0 {1 b' |  [
) ?5 }: n9 q$ V8 W& Y, e0 B$ g$ c+ ?    user-message (word "There are too many cars for the amount of "5 a3 o4 K5 G" Y! {+ B' m
                       "road.  Either increase the amount of roads "
, h) @6 d' U$ a! U2 T+ N                       "by increasing the GRID-SIZE-X or "* `/ |* [) @5 g. {* m
                       "GRID-SIZE-Y sliders, or decrease the "
1 k3 e. }* R: g: N7 R; F! B                       "number of cars by lowering the NUMBER slider.\n"
2 x/ U& m/ c' c0 T7 \                       "The setup has stopped.")# m9 M8 T/ g7 F) X3 ]/ o4 G. K
    stop
  L/ i4 a8 A7 ?: a0 g- X, I  ]/ b' e2 ~, t& h3 S$ t0 K0 ~
% D! E7 b5 L9 ^: R
  ;; Now create the turtles and have each created turtle call the functions setup-cars and set-car-color
6 F( [/ B/ h# y2 u' u$ m" d  crt num-cars( ~$ N2 Y' P9 z/ l& a+ {- \+ e+ j7 f
  [
& z# Q1 j4 N7 K& J1 T: z7 f    setup-cars
- w. T( t& j; r$ j; z# c+ P$ }    set-car-color
6 y: m3 l9 z$ F; p1 w5 p! A" ?    record-data
, l( i: k. ]( [3 l- h  ]
+ n+ F9 f! `2 r  c7 y; y, f; V8 ]& y4 \" \
  ;; give the turtles an initial speed" X& V5 [  o, h& u3 |4 ?9 J
  ask turtles [ set-car-speed ]
1 y4 i/ p# @( o0 F; {: X  q) B3 w# v) l7 h, U. f# B2 g% |
  reset-ticks
' \7 o# J! h* B3 _# b  y- p6 iend
: S) e  W) d: h7 L
" W+ U0 p1 \/ Z;; Initialize the global variables to appropriate values
' e/ l0 q  \7 Z) M9 sto setup-globals: A4 @3 ^, r8 }# }7 Z; ^1 d
  set current-light nobody ;; just for now, since there are no lights yet
$ c: k9 A6 H& d2 s  set phase 04 e# j4 x; L8 t& {: ^6 l) O# ?
  set num-cars-stopped 0
3 I  Y; ^) H9 Q! Z. y  set grid-x-inc world-width / grid-size-x
# E( T. n3 G" `- m. i# ?9 p  set grid-y-inc world-height / grid-size-y  m- q/ H3 r5 I
. x  p# }# ^* T2 g9 X
  ;; don't make acceleration 0.1 since we could get a rounding error and end up on a patch boundary
" B! s' l" X) Y# Y/ D0 D3 ]  set acceleration 0.099
; p: Z. Z# `* p: Y/ f* Uend
# l/ U" M' ~% ^* T, B* |; k' }( K# Z4 C2 g
;; Make the patches have appropriate colors, set up the roads and intersections agentsets,, X  G4 i% o; K# j
;; and initialize the traffic lights to one setting" T7 I( d) L2 T! Y0 E
to setup-patches8 Q3 i7 Z5 ?% d: ^' I1 W6 h- ?
  ;; initialize the patch-owned variables and color the patches to a base-color" B- q3 J* C! ?  C" _
  ask patches
- ^* V2 N$ n' y; [3 c  [- C/ i/ O- g/ Z1 ]* d# m# ]: n
    set intersection? false1 p( s# [5 J& n7 @3 ]
    set auto? false
, g: B* Y" X% d6 P0 e    set green-light-up? true9 ]) `/ n; m4 \: f6 X8 j# g  D
    set my-row -1
& W3 |/ O( R9 }$ W, h, E' P" z  O3 w    set my-column -1
8 u2 e& V6 d5 S- l    set my-phase -1) v) n2 u5 W" v! E8 e, X, h7 x
    set pcolor brown + 3) s. K# T. A/ o, v# L
  ]
$ ~9 y* h/ g0 d; {: k* R# }/ z% R6 O' I5 Z
  ;; initialize the global variables that hold patch agentsets! h2 w6 `$ J* q$ y5 N4 i
  set roads patches with% R8 c9 v! d9 G; ]  n
    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) or/ p1 O# ?0 c! a
    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]
0 l, L& ?7 z& h' P2 x0 T  set intersections roads with
8 }) f4 O4 C2 I3 p+ n$ P    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) and
. E/ U' j4 J* n% y3 R  {7 `  g9 f    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]
$ f2 l( q! Y2 k! I/ m" Y# r0 N7 Y: x) D9 N5 h/ C6 O, A" L- g
  ask roads [ set pcolor white ]
$ }. _  T2 P" b    setup-intersections4 g5 M2 P" P/ X3 w
end
$ ]3 W$ f3 \. ~" H# a' P其中定义道路的句子,如下所示,是什么意思啊?
' j1 I* D0 g/ W! @" i. w set roads patches with
$ e* E' G) r0 Y/ T: C* t  z- ?" N9 \4 m    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) or
7 b$ t# g* L% i5 d/ C    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]) q+ @% c$ E2 q- q/ Q
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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