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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。; c' K2 k3 y7 R( Y0 v; C: @
netlogo自带的social science--traffic grid这一例子当中,! X" O( ^; y7 `$ g* g% B
globals( X; v- m7 ?9 k" }& G, ]
[
, R' t" e+ T9 s& D( R$ \( r0 z1 h  grid-x-inc               ;; the amount of patches in between two roads in the x direction5 q, {/ O' {. S' u$ B4 r: m9 a: Z- g; P
  grid-y-inc               ;; the amount of patches in between two roads in the y direction; ?' M0 e( @* _5 l/ K' s# O
  acceleration             ;; the constant that controls how much a car speeds up or slows down by if
* f1 H5 V& m4 H2 @                           ;; it is to accelerate or decelerate
% P3 ~6 g) G9 e. R+ f* N  phase                    ;; keeps track of the phase  @& j7 `7 W4 R
  num-cars-stopped         ;; the number of cars that are stopped during a single pass thru the go procedure7 J7 C" [0 v- Z# M6 a% U1 H" p; ]
  current-light            ;; the currently selected light
  G+ N3 M) Y* c. E1 b* {8 i8 a" P0 o) T( D
  ;; patch agentsets
$ v" ?1 z) V+ ~# R( B. c7 Y  intersections ;; agentset containing the patches that are intersections
: h+ ?$ k8 g0 w7 _  v  roads         ;; agentset containing the patches that are roads8 R1 }2 a9 \5 n  P6 v
]: c; L3 v7 F+ W9 k3 [; o

0 k( q4 l' I9 Sturtles-own* c- R$ P# A- H% w
[
7 w4 G7 ?$ B$ V" l. t/ V: J  speed     ;; the speed of the turtle- G. V. a0 J1 S
  up-car?   ;; true if the turtle moves downwards and false if it moves to the right
$ L- Y/ a6 I$ C  wait-time ;; the amount of time since the last time a turtle has moved
+ n( h, [, e$ Y' ^]/ W* z7 F9 e6 u) R" z
; d" Z! ]7 V. q/ Q1 _5 }
patches-own
: V! E& `6 V  m[
4 N1 z8 C; `8 i7 B* Q  intersection?   ;; true if the patch is at the intersection of two roads# V+ Q8 c$ \7 M
  green-light-up? ;; true if the green light is above the intersection.  otherwise, false.2 e! @/ C+ T4 d0 f+ I
                  ;; false for a non-intersection patches.; K* K+ s1 j* ^
  my-row          ;; the row of the intersection counting from the upper left corner of the
- `: {* r" P) K8 B7 ]                  ;; world.  -1 for non-intersection patches.
1 l+ D0 K) I' y; W' h) U  my-column       ;; the column of the intersection counting from the upper left corner of the
  A( {9 k5 x* k0 r" h2 R' s: L+ M                  ;; world.  -1 for non-intersection patches.# U$ H+ I' u* O0 N
  my-phase        ;; the phase for the intersection.  -1 for non-intersection patches.$ Y" D7 Q& Q# I& d
  auto?           ;; whether or not this intersection will switch automatically.% n0 s. U( m  ^  p' s" i* S2 j
                  ;; false for non-intersection patches." v3 q6 t& E. d9 d
]; ~7 g. G; `+ @" F, U& b0 K
, M" t. N1 S4 M7 S
+ t% Q% C9 S- R1 S4 b
;;;;;;;;;;;;;;;;;;;;;;
1 ]8 D7 Y4 E# d  X4 x;; Setup Procedures ;;) D8 c9 N$ Q0 v
;;;;;;;;;;;;;;;;;;;;;;; B* H! S* Y5 X4 y  R! X$ C
8 q* u6 l' h- i+ Z- b
;; Initialize the display by giving the global and patch variables initial values.
; B; T  B; ]/ M( z8 R! f* ^;; Create num-cars of turtles if there are enough road patches for one turtle to
; A$ I- _* `- ]' G5 Q( f( s: j+ U;; be created per road patch. Set up the plots.
2 t) z9 S. @. K% [, o3 Lto setup4 r! W8 i- J% s; k" f1 V" i3 ^5 d
  ca
& ]0 J$ q% h* T7 O# \- g/ i1 Z  setup-globals
. g. D7 A* w- E9 u- r+ z, F2 q4 \. |- t. Q4 }; u+ {
  ;; First we ask the patches to draw themselves and set up a few variables
; t4 q/ R7 K: q1 l  j  setup-patches
/ B3 v5 {! t  t$ J/ r! {- f$ l  make-current one-of intersections
' j7 _  k+ P! Q  Z# U/ O  label-current: {$ Z0 _0 I- Y8 ^8 ?

) f  k# G$ ?, Y) G0 L. _  set-default-shape turtles "car"
, E5 U+ f% a  |% v1 M
, e) I) d) X$ D, l: v3 J* [  if (num-cars > count roads)2 W8 Q+ S  o2 P
  [
3 y0 S" [, G" m/ ?    user-message (word "There are too many cars for the amount of "; o2 R5 e3 n- _9 u6 S
                       "road.  Either increase the amount of roads "
7 j' t  m2 x& U% @$ [1 a' B                       "by increasing the GRID-SIZE-X or "
) a3 ]* U2 t1 {& |- \                       "GRID-SIZE-Y sliders, or decrease the "
4 r6 C' A0 x0 z/ b! L. A" ?                       "number of cars by lowering the NUMBER slider.\n", W- e! O( v; j% i" x% I& z
                       "The setup has stopped.")+ [1 p! o+ J  \% V* \9 {
    stop
, W1 g) v/ {6 V7 f9 ]  ]
3 l. q/ k% D, `4 D, {( H* {9 X
/ y4 ]) Y) f) a& p  ;; Now create the turtles and have each created turtle call the functions setup-cars and set-car-color
7 ]+ ~$ @7 f$ j% w  Q9 V  crt num-cars
( h7 u) l2 N/ W2 j  [
% w2 V, B7 t! c7 ]    setup-cars
' u( g- u, c3 J) u  e% W' s    set-car-color# y6 L( R6 [  e) ]: g% M
    record-data" ^1 p* `# ?, Z  O: ]" M
  ]
1 V' q, Z+ X( b, N, T/ A3 n  F
: I- R2 \) q0 {1 a  ;; give the turtles an initial speed
. u) s/ ?8 ?8 s% f  ask turtles [ set-car-speed ]. h9 F. n- S7 S% r' c( e6 l

  _" p+ B3 _5 W  reset-ticks* x8 _# f6 G3 g, U- Y4 {% P7 P: y: M
end* t& X8 e# S2 K/ n8 b( b

6 O. Y) P; H6 [. x' e4 D;; Initialize the global variables to appropriate values
1 x) ~9 G  z/ C  q6 _* Z& Eto setup-globals5 u3 u" ]5 O* v: N
  set current-light nobody ;; just for now, since there are no lights yet
9 K: D9 b1 [3 ^) Q" o  set phase 09 k# i2 u' I' ]2 h8 m, B$ w  o
  set num-cars-stopped 0
: l# [- Y+ V3 X% X  set grid-x-inc world-width / grid-size-x- R0 {9 H. a2 i! E" q. i
  set grid-y-inc world-height / grid-size-y$ M+ c2 x2 h, O' k: o+ f5 ~

% w5 q* N( q( _5 E  n' s" C  ;; don't make acceleration 0.1 since we could get a rounding error and end up on a patch boundary$ J, I0 o. ]2 p/ }) O) C; d
  set acceleration 0.099) d. s, w, C% Q2 M% @1 z
end
: ^1 e9 X/ W2 }; D; _- C4 B
! b# _5 A5 L( _( |3 ?/ A;; Make the patches have appropriate colors, set up the roads and intersections agentsets,) k3 I: b' B0 I) l' B
;; and initialize the traffic lights to one setting- I# r% v- p0 |' q# s
to setup-patches$ g1 p0 L; j+ D& W+ s" D& ^* ^
  ;; initialize the patch-owned variables and color the patches to a base-color  r( ~) s6 R6 ~2 e* r
  ask patches
" U& p" n% Q; Z4 u  [
+ d) p7 o) g; M6 S# M3 F0 c+ w) c    set intersection? false- V4 r' p4 @/ k  s, u  m' m  U
    set auto? false( q) C& t" }7 g6 R% s" T' `& T9 H
    set green-light-up? true
6 E6 q, s5 o& o) P7 m+ y) B    set my-row -1
/ v, X8 r6 q1 v6 J: b! e    set my-column -1
* D* S4 s& _7 y% \$ w9 p    set my-phase -1. J  e$ \' A8 A- h5 u
    set pcolor brown + 3
' {3 z/ Q& P- M; f1 C! a( M. b  ]
3 o- |/ n: m+ C' l& I6 u, P% I9 M# r: w6 r  N0 v
  ;; initialize the global variables that hold patch agentsets: t9 ~  `* h3 \- A) t& X: f. |7 ^
  set roads patches with1 s. Q& X4 q8 A$ T
    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) or
& c0 w4 l" Q7 Y* _/ Y, {2 f    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]. {" I, n- |: T; s8 I' A: v+ \
  set intersections roads with% t* Z7 d) u* R
    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) and- }0 ]3 ]5 ]/ A1 d) y
    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]
& G9 T1 c8 J$ W9 R6 R" G) k7 ~% D! \, T5 g$ F5 s" G# ?2 i
  ask roads [ set pcolor white ]# W0 t1 Y. W7 ?0 ~
    setup-intersections+ [% u/ ?. ~* M/ @; y" Y( N
end* B0 o; I5 `/ A$ b% p
其中定义道路的句子,如下所示,是什么意思啊?
1 o- ?5 {7 M$ |, Q6 E5 _ set roads patches with
, e( }3 Y* N8 `# A4 ^5 z6 l' C    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) or
; u9 y( T/ q7 L$ u; U3 u    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]
; U& ^! W% }8 ]) _$ p4 R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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