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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。* z8 a% I' e) `3 ~6 t, ^7 h
netlogo自带的social science--traffic grid这一例子当中,
  b. C6 g) ]6 U! z0 M! r" dglobals
6 H/ P1 A9 r: v1 Q5 y[
& Q: g( Y2 k8 ~$ f3 f  grid-x-inc               ;; the amount of patches in between two roads in the x direction
% ^4 u4 H. K7 \4 r+ b# V  grid-y-inc               ;; the amount of patches in between two roads in the y direction& J% G+ h& d+ X* H
  acceleration             ;; the constant that controls how much a car speeds up or slows down by if3 d) S' A( y$ C' v
                           ;; it is to accelerate or decelerate
) U6 c3 b' Z, N( Z  phase                    ;; keeps track of the phase* h* R8 f# g; h
  num-cars-stopped         ;; the number of cars that are stopped during a single pass thru the go procedure9 X: }( o4 ]/ c, W+ R
  current-light            ;; the currently selected light
. e& V* Q( V* c& \/ \$ g
. d. K4 k# K9 B. L& S' t0 L3 _% I3 |: p  ;; patch agentsets  y0 z0 q2 ~+ R% T! K/ F% A; T
  intersections ;; agentset containing the patches that are intersections  A( O# q* A  \7 f9 V# I2 x3 i( I" S
  roads         ;; agentset containing the patches that are roads
7 W0 V* a$ I* K' S! i" e1 n]  b7 g2 f' @' h7 w: I7 ^# n

7 {% ^5 G; e! Y/ f; iturtles-own" e5 a. k) {8 H" M$ s
[/ E% N" f, V: ^0 u/ [( ]7 a
  speed     ;; the speed of the turtle
  t+ A4 G. x' q7 G  `5 c  up-car?   ;; true if the turtle moves downwards and false if it moves to the right
2 F# Y; _/ n7 |9 i! _7 A( A) m& s- x  wait-time ;; the amount of time since the last time a turtle has moved
" W. @$ V6 I, l  ]]) j& D2 t. y$ ^. w) L5 p$ Q' X

# \, r4 V+ I9 F# ?0 epatches-own
' s3 x) u" C- f$ n[( Q- H; f/ T8 v: D7 ^+ ?0 y
  intersection?   ;; true if the patch is at the intersection of two roads
  S7 N% b% Z1 x$ I; n( Y( N  green-light-up? ;; true if the green light is above the intersection.  otherwise, false.) R+ i3 F" ^. q+ D* ~
                  ;; false for a non-intersection patches.
8 M# ]- t' y/ U5 j$ j- t5 T* \  my-row          ;; the row of the intersection counting from the upper left corner of the
: y1 O, }: h, \% s0 E7 h                  ;; world.  -1 for non-intersection patches.
" _) A3 X2 D: X9 ~( u  my-column       ;; the column of the intersection counting from the upper left corner of the: X) d/ v& w+ m) S& i
                  ;; world.  -1 for non-intersection patches.
/ @/ Z" E5 z: w$ m0 J  my-phase        ;; the phase for the intersection.  -1 for non-intersection patches.1 D* E7 z0 \0 J* o) |" G
  auto?           ;; whether or not this intersection will switch automatically.' U- i- x3 w0 @! r6 e' O: y/ l
                  ;; false for non-intersection patches.
2 E5 Z! C! t& ^9 z; T5 @]
' ~5 g: b8 d2 K$ y6 ]: z; c) @- |% y+ O0 U/ m) s  ^2 ]

) }# O, D8 _% K. t# e1 G;;;;;;;;;;;;;;;;;;;;;;  X- y2 ?& t$ G8 s5 k) o
;; Setup Procedures ;;
! [$ u7 d& I9 P# F: S0 d! k3 D;;;;;;;;;;;;;;;;;;;;;;
3 E" c5 C. {( z* E* Q5 p( ~; p; Z8 p
) B, y8 f0 Q' p4 L;; Initialize the display by giving the global and patch variables initial values.
# D1 Z- B) j) c1 C8 A;; Create num-cars of turtles if there are enough road patches for one turtle to
) y# l5 ]& @5 W/ P$ D, \% {;; be created per road patch. Set up the plots.2 d( F2 w$ ]$ D9 l, T1 n+ f3 Y2 Y
to setup# v) V0 y; H# P' V$ s
  ca, W! c6 k9 \) Y. Y9 ]3 Y
  setup-globals
; y* z5 ]- j& ]
1 N. S/ M- L3 s# x. {  ;; First we ask the patches to draw themselves and set up a few variables! U/ w6 Q% t8 c( s( L- z
  setup-patches
0 R) t+ M! v. [1 m  make-current one-of intersections
5 g9 `" A2 o$ D! B5 u2 L  label-current
0 {# Q; |6 c' [% i3 F% ~, k) X$ j6 b) m; ~: n' i( ~
  set-default-shape turtles "car"5 ^# f" A. i2 ~8 \
9 g5 h& H9 z! s. |. P( q3 G
  if (num-cars > count roads)
/ I/ h) a0 v7 v8 v5 q5 T  [
5 F) i$ A6 R7 K0 L5 G) p) p    user-message (word "There are too many cars for the amount of "
. T5 g. |* ^$ L. X9 B                       "road.  Either increase the amount of roads "6 }) T8 |. `; [7 b3 [( ^0 ]0 A  r
                       "by increasing the GRID-SIZE-X or "
& a& q4 V- r, f( G                       "GRID-SIZE-Y sliders, or decrease the "
% p3 M& S" l5 b3 y                       "number of cars by lowering the NUMBER slider.\n"
0 [, ], V7 ]: l0 g" A  [                       "The setup has stopped.")
7 b( Y' ^- a: T; F' L' T    stop
4 d. @0 d% }  J& c" s9 A. y& t7 {  ]4 N( Y$ m7 e; W6 T1 d6 B

% V" _( [3 H% T( K1 T% ]  ;; Now create the turtles and have each created turtle call the functions setup-cars and set-car-color5 K3 `) Z) m3 Y! g* ^0 B
  crt num-cars: R/ X: ]! |7 W
  [9 V, x+ d. r8 O2 Z
    setup-cars
1 o; S) {" [- P( d8 K6 }1 p    set-car-color
: N5 _8 M9 T6 A+ y    record-data* j' i  g1 g, i0 @& A
  ], k9 ]* }* S  q5 C

6 p8 ~: Q" s9 ~5 I" M  ;; give the turtles an initial speed
" Z; G" z" \/ ~9 _  ask turtles [ set-car-speed ]: j  W2 \) \% k2 X

+ t" v( D* ^, M+ R, l  reset-ticks, \0 E/ |0 t2 ?/ V
end
9 V9 _) x8 Z4 e# H/ z; O& K3 H  B" N' h. w/ ^) ^
;; Initialize the global variables to appropriate values& G! ]* ~2 h' s, u
to setup-globals2 I$ G* {, R; W$ H, ~& B6 @/ u% s
  set current-light nobody ;; just for now, since there are no lights yet' ~* |5 A& h0 w
  set phase 0
# S9 x9 }6 N" @0 G# C" ~0 T! J1 |. ^/ }  set num-cars-stopped 0* H- C) X: A& e
  set grid-x-inc world-width / grid-size-x
, l) l! n2 Q  _4 ^4 @& S2 ?  set grid-y-inc world-height / grid-size-y
5 ?! F- J& X- y. B! q- t# `: ]/ N% ^. N  C$ B$ [! I
  ;; don't make acceleration 0.1 since we could get a rounding error and end up on a patch boundary; d3 n* e, q$ q. z7 m2 w
  set acceleration 0.0997 \3 E# v/ d7 o' U1 r
end
9 B3 y2 N' Q& z- M7 N4 q5 A7 B' K  e& W! [. y
;; Make the patches have appropriate colors, set up the roads and intersections agentsets,' G2 I; I9 }5 W+ K+ e
;; and initialize the traffic lights to one setting
5 x+ }0 ^2 A) s% Oto setup-patches
6 H% M; q7 b( W# y  ;; initialize the patch-owned variables and color the patches to a base-color; s9 C1 S1 {+ P) Z
  ask patches
3 x5 S6 {2 X% ?  P. a8 w( U/ \  [" u' z* x5 U( A: z% M  {3 V  T1 W4 w
    set intersection? false6 }' e4 x4 v* Q% v
    set auto? false
6 s3 e* n  G) Y: ^+ i$ K- u, v) I    set green-light-up? true
: @2 ]8 B5 g8 f) X. q. V+ ?" B1 ~    set my-row -1
+ p3 ?2 X/ H" T) t    set my-column -1
" T+ P4 q0 a  d: U7 A    set my-phase -1; ]: E+ x/ `- U
    set pcolor brown + 3
2 V7 N4 j# d7 A, K8 l9 q  ]
9 b  N7 x9 H. g+ \3 I4 h& J$ ^- }% a1 {5 H* j3 g+ r
  ;; initialize the global variables that hold patch agentsets
5 w: w! e7 o7 e8 g) _  _  set roads patches with/ C( a2 }; s2 a+ U7 k
    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) or! Y2 p: [: g0 d
    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]
, Z6 m( [2 V1 v1 c5 ?1 k, @9 P9 C  set intersections roads with
3 x' P) j1 @6 ]  N; h. p6 O. \4 a    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) and; r& q( O  o4 J. e- k" U/ n
    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]+ P6 i  o" t+ X6 @

9 J, N) `8 v, d" m  ask roads [ set pcolor white ]
. j0 x0 a0 g+ o/ p6 T5 U! e  ?7 w    setup-intersections
2 l% n4 m! J' K# i5 p" xend
. U) l. Q$ \* q6 M: f3 g其中定义道路的句子,如下所示,是什么意思啊?
9 R/ K0 q" h1 D set roads patches with
) n$ ~" }) W( E3 [7 o  D1 j( M    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) or
2 c, W6 G& p% T% \+ s    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]' s7 I' R6 w- x' _8 D0 p0 v
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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