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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+ q) a3 n' enetlogo自带的social science--traffic grid这一例子当中,% F0 N4 W9 a) t# L" N  L3 ], S8 _
globals
8 J$ ^4 e, `, M5 Q; q+ c[
- [: e1 x2 m- ?. n) I* C7 ?. Z. y  grid-x-inc               ;; the amount of patches in between two roads in the x direction
6 h, b1 ?' P# H% I8 f9 S& w$ F  grid-y-inc               ;; the amount of patches in between two roads in the y direction
; T) i  \. u9 s( w1 B3 y  acceleration             ;; the constant that controls how much a car speeds up or slows down by if
" A) i; l% D6 v6 b4 _. q1 Y                           ;; it is to accelerate or decelerate
3 Q3 B' D& I- N( H& [+ H) J7 d% X  phase                    ;; keeps track of the phase
" B6 w6 `9 b  W9 b+ F4 ?  num-cars-stopped         ;; the number of cars that are stopped during a single pass thru the go procedure
% n" t! |8 |# A3 K5 N. V, X' ^  current-light            ;; the currently selected light9 S9 U# h, [8 b& y' R
  ]; ]1 `, {: i
  ;; patch agentsets
7 K3 n- H" p+ b/ ~2 `4 N  intersections ;; agentset containing the patches that are intersections6 q# {9 v  D/ k8 T/ o" s
  roads         ;; agentset containing the patches that are roads: I: B  N8 T3 G, ?1 q2 }4 s
]
5 c1 v3 y; s" V4 H9 S: h0 L- l# k6 y# @4 _4 C
turtles-own; k3 ?8 d5 j( @6 ^: w% S& ^! i' t
[# Y9 z( q" q% f1 B. k4 r
  speed     ;; the speed of the turtle5 j+ A& {, A5 P+ C; x% [( D
  up-car?   ;; true if the turtle moves downwards and false if it moves to the right* _& m: ]1 V* B& t% n
  wait-time ;; the amount of time since the last time a turtle has moved
3 V( ]. c3 A! _- E3 @3 l  B]
1 n% M; S- I/ x; g% t( M; ]( u+ ?( p- Q4 v4 `9 k  |- X
patches-own
1 z6 p' s0 U4 c  |[6 C+ K* u7 f8 _% L6 c3 P- v
  intersection?   ;; true if the patch is at the intersection of two roads, `' s) s. F; u" o: f
  green-light-up? ;; true if the green light is above the intersection.  otherwise, false.( d/ |; M$ [- B! z+ U' \* N, |
                  ;; false for a non-intersection patches.
  v( L: F0 p0 J" j, e: s/ M  my-row          ;; the row of the intersection counting from the upper left corner of the
6 X1 \# C1 a2 ^* C: v' l                  ;; world.  -1 for non-intersection patches.4 k; {' }- ~( P0 F
  my-column       ;; the column of the intersection counting from the upper left corner of the
4 d4 ]9 [; D' h  E& m5 |0 O                  ;; world.  -1 for non-intersection patches.9 l: y) R/ Z, {% S1 C( Y
  my-phase        ;; the phase for the intersection.  -1 for non-intersection patches.
& V; R' a4 ~5 P+ ~8 g+ F( z  auto?           ;; whether or not this intersection will switch automatically.
6 }3 ?" X3 C- M7 E( w                  ;; false for non-intersection patches.5 a6 ?' y7 \) B$ X3 S! t- O  Z; v
]3 b1 l! J" @; ]
6 L4 {: b6 \. D/ B; u( D

: d3 F4 c; i  h3 R6 i( T;;;;;;;;;;;;;;;;;;;;;;5 {( U1 y3 T- h  P6 C* f$ N
;; Setup Procedures ;;7 j/ N# ^" S1 p' }
;;;;;;;;;;;;;;;;;;;;;;
% Y3 E) v) O9 H) y" c( i1 ?5 _/ y' C* U% u2 `/ k
;; Initialize the display by giving the global and patch variables initial values.
) w' H" }4 f$ K3 g! d0 d( C;; Create num-cars of turtles if there are enough road patches for one turtle to5 W5 T; w$ y- z6 _8 Z* ~) M- f
;; be created per road patch. Set up the plots.
  J6 @$ |7 T7 Sto setup
4 z  b4 D% f8 C2 K  ca; Q( I) j, K2 w8 \$ p
  setup-globals& S% {5 ^' N. }* ^

, ~0 v" z% b; T  ;; First we ask the patches to draw themselves and set up a few variables
) Z4 C: K# m8 L. ]$ o. ^+ r6 s/ d4 a  setup-patches9 \. M6 D* h1 ^. \; a6 |
  make-current one-of intersections
" c& ^$ v' T& s  label-current
9 c. z9 p" Y5 j0 m, _" p0 R
" m8 q" [1 Q* S  set-default-shape turtles "car"5 I- u" L6 e5 S% H# t' g/ G
7 Q  a3 j8 {$ b0 A9 C
  if (num-cars > count roads)
+ s& j: G  d1 C& m  [) Q* i4 X7 `; d9 z. f* j0 V
    user-message (word "There are too many cars for the amount of "5 `" W' w" U) R6 f! W! X! k
                       "road.  Either increase the amount of roads "
) z) K6 I7 w+ S+ V$ j, K: s                       "by increasing the GRID-SIZE-X or "2 O0 R" W  `7 m7 Q) U& v  t
                       "GRID-SIZE-Y sliders, or decrease the "& u4 B" r8 ]9 p+ Z/ C: \* [' ?
                       "number of cars by lowering the NUMBER slider.\n"
$ `+ Y5 R% a' U+ J3 Y- T. W% U                       "The setup has stopped.")& G$ @, i: Z& r
    stop
! p3 k8 j( x' R  ]
. L& e# h4 K; \! e) T# l5 b2 ^# I8 z8 H' S* K& u; _' k& A
  ;; Now create the turtles and have each created turtle call the functions setup-cars and set-car-color
! b0 i3 S; S/ i1 u+ q; H/ H  crt num-cars5 [* ?) m, Z1 I% Y% G5 e
  [  d$ w$ A" [: \6 ~1 U
    setup-cars$ Y* W$ {: m8 h2 }# F+ v
    set-car-color. c0 B2 _  F+ s3 Q2 Z7 n* D
    record-data- j. }8 s' G2 ?; N# Q) m7 e6 G  r
  ]
# b" |2 ^$ g, i2 @% v. t; u' W+ u
: J8 J& ?5 v( ~4 G, m+ d  ;; give the turtles an initial speed$ J) u' v  K; _, T% @0 M2 Z8 {$ @
  ask turtles [ set-car-speed ]
; k9 |. T$ Q& d7 p2 T) v0 ]' t
3 y$ M8 s' @  s8 K& Y1 W* C  reset-ticks
* r! R7 N  b8 v' P5 ^end
$ ~  s0 {. t; {" z' j; J7 d
& O. D) Z* G( `, l;; Initialize the global variables to appropriate values
! g9 h1 b+ z6 N$ Rto setup-globals8 O2 _+ X- O1 a' I
  set current-light nobody ;; just for now, since there are no lights yet
( ~6 I# V6 K! [) _: F3 v  set phase 0
3 j4 J( M( o* P! c1 z  set num-cars-stopped 0# g4 I: [/ Z& F  X! [( I2 C
  set grid-x-inc world-width / grid-size-x% J* ~; G# ?  F5 q0 I7 V
  set grid-y-inc world-height / grid-size-y
+ G3 F4 ]3 }7 `$ K7 j; S$ [: x5 h: K1 A8 D5 n
  ;; don't make acceleration 0.1 since we could get a rounding error and end up on a patch boundary+ G  I; P3 T( _, M7 m3 M
  set acceleration 0.099
/ |- f8 q. b" ^) i. e  wend
, J) V0 b) ~; W+ e2 h
& s0 a$ y7 W# G: [' j5 ?" W# Q9 ]8 _, _;; Make the patches have appropriate colors, set up the roads and intersections agentsets,
: a( s1 `& n8 ~3 p% {2 H, a5 y;; and initialize the traffic lights to one setting9 w, u4 b8 ]' k  U* H+ l1 _4 m8 \
to setup-patches. p6 j' N1 d' l
  ;; initialize the patch-owned variables and color the patches to a base-color
2 Q2 C9 \6 E4 z. H3 M  ask patches% P5 p4 ~" \; k" U- V* g
  [2 b7 ^& @' ^4 `1 x
    set intersection? false
1 }+ k" T- P5 Z$ I+ L+ W9 x    set auto? false
% d3 U- f# T, I7 D    set green-light-up? true
/ }- b# h# _0 c/ d: c    set my-row -1
% e; u7 l! w5 q4 n    set my-column -1
. M$ W  G% g- a    set my-phase -1
" a) D0 b2 \- H/ y+ r6 H    set pcolor brown + 33 ]3 r+ d6 h8 }3 w% v, w
  ]+ j; V! c8 R1 B& W) \- R" D
, V" p2 [1 \3 D& H
  ;; initialize the global variables that hold patch agentsets  f. R2 N- b& D: N; [; H% z7 @7 w6 P
  set roads patches with
. @6 `; b1 r8 x# B    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) or
) T0 m) D8 a1 R% u    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]
( e% h6 z4 `1 H; v  set intersections roads with1 t1 r6 k4 c( m$ ?0 p
    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) and
! u: t, q& a: {, i% D    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]% w! u$ `( V3 Y$ o- v' a
) z1 y3 H5 ^* \% @" n
  ask roads [ set pcolor white ]9 @5 S4 e  a8 Z) T: K* R2 Q/ y9 c+ u
    setup-intersections
5 c' J' V- ~. u2 h& \# iend; f  S' w9 U+ C) i
其中定义道路的句子,如下所示,是什么意思啊?
5 d( w& y1 K* ^5 o& R set roads patches with
) d3 n. w9 v; o    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) or
% z+ x/ M! I5 L9 U" i) G$ h    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]
% D9 P; X2 S& H, ], w7 n; O2 \4 L$ j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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