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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。: }& E  c" p' Y
netlogo自带的social science--traffic grid这一例子当中,* `" O: P* I% k( _
globals
) ]5 z# a2 Q3 N0 |; ]) c' F[
" O6 ^  e7 J' {5 [. L6 \5 X5 i; @, y  grid-x-inc               ;; the amount of patches in between two roads in the x direction
/ h* O9 ?1 w9 ^$ b7 ]& c  grid-y-inc               ;; the amount of patches in between two roads in the y direction
5 z' k0 _9 [* |: b3 C9 b3 X8 c  acceleration             ;; the constant that controls how much a car speeds up or slows down by if; Z; |) A3 f3 G  |! V! z  c2 _$ {& \; v* G
                           ;; it is to accelerate or decelerate
' H9 n" O5 G+ k% I9 _. ?4 m  phase                    ;; keeps track of the phase* K4 x, v5 o7 W
  num-cars-stopped         ;; the number of cars that are stopped during a single pass thru the go procedure4 c4 d/ h" G7 p( u% ]4 d. Z8 h; y- _
  current-light            ;; the currently selected light
! r8 H0 {8 j% G2 {# m
+ x$ m; |* A/ A- E  ;; patch agentsets1 ]5 H8 S1 c* f6 w- L
  intersections ;; agentset containing the patches that are intersections( f' |+ h* Z/ o2 T0 j! D
  roads         ;; agentset containing the patches that are roads* s' h" |' T! X% H: b) @2 ?
]6 ^& e$ {3 K/ e
* y  O3 t* z0 Z6 {
turtles-own
  `! X) E8 p- C$ T  i) ^[8 W- W* w- {+ V6 c
  speed     ;; the speed of the turtle" Z& I8 M! W4 k* ?3 b
  up-car?   ;; true if the turtle moves downwards and false if it moves to the right$ ~$ ~) u& |) R  }4 r
  wait-time ;; the amount of time since the last time a turtle has moved& O7 l; V/ h, R% T  K( w
]% u2 w9 d- ]/ M. `

2 _0 R- w; x( E/ x6 D) Y9 }* T4 [patches-own
7 n! c' [, {. m% d5 b4 W& c[7 a6 K& X4 m- N; o
  intersection?   ;; true if the patch is at the intersection of two roads6 M7 S6 Z4 r7 L3 n
  green-light-up? ;; true if the green light is above the intersection.  otherwise, false.6 A; b; }: e5 `6 x
                  ;; false for a non-intersection patches.
% ~# v( l; _2 s& e2 u7 }  my-row          ;; the row of the intersection counting from the upper left corner of the
- N1 r) A% O! X2 n                  ;; world.  -1 for non-intersection patches.
) S+ _' `4 A+ f& v  \% ^  my-column       ;; the column of the intersection counting from the upper left corner of the" `2 e3 Y$ j4 }+ G- c$ z( A" a8 M
                  ;; world.  -1 for non-intersection patches., u4 g) g* [/ C+ w/ \6 q+ C
  my-phase        ;; the phase for the intersection.  -1 for non-intersection patches.# S8 ~2 |! D1 ?/ {3 y0 G
  auto?           ;; whether or not this intersection will switch automatically.( b- Q5 K. t, G& e& v
                  ;; false for non-intersection patches.
* F1 I9 a, M+ w/ J& h' E& r]
( p7 a( F6 k. l6 o1 k  S+ v* y' D4 x; N1 @) _* r& B! @$ J

% d0 Q. i- p+ ]3 ^" |) ?;;;;;;;;;;;;;;;;;;;;;;
( p! S; y; L" v7 k8 _;; Setup Procedures ;;
# Y/ [6 m% R4 u* C8 B1 _;;;;;;;;;;;;;;;;;;;;;;
! D3 V+ \+ e4 A; [! V9 V, M. m$ ~' z6 G
;; Initialize the display by giving the global and patch variables initial values.
2 Q- @1 x0 N- o) [+ L% D" Y;; Create num-cars of turtles if there are enough road patches for one turtle to4 W/ G! B6 S5 V4 \, `
;; be created per road patch. Set up the plots.5 _- \( V; D2 E+ ?( y5 o
to setup
+ p/ f4 u) Y4 i1 m/ t( z. A  ca
' [" i0 Z7 f# N4 I$ A' Y  setup-globals5 J1 A6 ]! i# n* O. d' C
! c! V7 w( |+ d
  ;; First we ask the patches to draw themselves and set up a few variables
1 m: Z; v1 S' [' ^7 \: @  setup-patches. {1 s* o1 s7 {
  make-current one-of intersections
" B- x- \; Y, X4 d2 W  label-current( ^! C- W9 u. W* v, i7 h$ C2 v
* w- w% z6 T- j: q& ]$ H
  set-default-shape turtles "car"
! L7 k! L- s8 ?: A& w0 ^
% a& A8 K) f4 ^  if (num-cars > count roads)( d( F& l* Y& k6 M! q+ m/ G: i
  [
: G' f9 }$ S+ I" w. S    user-message (word "There are too many cars for the amount of "2 J5 S; K8 p* b: ^" Q' o
                       "road.  Either increase the amount of roads "* J4 S, r0 V9 W; P
                       "by increasing the GRID-SIZE-X or "
% C% ^/ d2 G4 F0 S; c                       "GRID-SIZE-Y sliders, or decrease the "& `: P% W* @2 l4 d/ W0 m& p4 h
                       "number of cars by lowering the NUMBER slider.\n"
7 K; d. {7 E2 s, o* G                       "The setup has stopped.")- F3 s; j5 q3 s7 I$ H) e" u+ Q
    stop* N. m: q' k# j6 S
  ]
* D/ t; q+ Q/ ]8 X
9 S6 F6 z( d0 J. `; }, e  ;; Now create the turtles and have each created turtle call the functions setup-cars and set-car-color! ?. E/ A3 w  D6 ~
  crt num-cars+ b; k& e+ U) K# E5 s
  [
/ n& j0 O7 r5 ]: U9 _    setup-cars
" M( I; E3 `7 ~    set-car-color3 Q) T, s$ d+ r8 ]! n3 K4 w
    record-data. r- }; Q! o- S: n$ M% o$ ?
  ]
  Z0 K. E) j. |2 s% a' \# L
# l. \, x" |1 ?' X. s6 d  ;; give the turtles an initial speed
9 X; R& S- l2 [% a: b9 O  A9 c  ask turtles [ set-car-speed ]" ^) y1 Y- h  D7 L6 \) m

% F( o% `: ~9 T- s) s  reset-ticks
$ S4 S9 C% |% Q+ P3 l! b8 F$ jend
- R: x! ^+ S) P4 P8 B0 S" X. ?1 A$ p5 J8 d8 x. j, g
;; Initialize the global variables to appropriate values
  c' V# T4 }& U3 \1 Lto setup-globals
/ ?. G) _; C6 \+ f' T$ B  set current-light nobody ;; just for now, since there are no lights yet
6 E. G! x  z& o  U  `) z  set phase 0
7 ]  V! J/ M( Z1 W  set num-cars-stopped 0; J& J9 K5 ~. X5 A# V
  set grid-x-inc world-width / grid-size-x4 \3 Q, q, K5 M4 o: \7 p
  set grid-y-inc world-height / grid-size-y0 O: L2 U9 v! z, D' ]

* i) n4 u& d6 n: m& [  ;; don't make acceleration 0.1 since we could get a rounding error and end up on a patch boundary
) [1 A3 n2 L1 B* U% E0 d# }/ S% U  set acceleration 0.099/ h3 q" T$ u' b& z: p$ z4 D
end& q, j3 V1 k* _8 S& A/ ^

+ a2 H3 F* D- y, q) w9 `+ @;; Make the patches have appropriate colors, set up the roads and intersections agentsets,
9 o; l1 Y9 k3 j  D0 Y;; and initialize the traffic lights to one setting
& A; m! J* M& L, fto setup-patches
  q: ^6 \8 j" \  O  ;; initialize the patch-owned variables and color the patches to a base-color
) T, w, n9 z% }* y  u0 @  ask patches- i) h' g7 \8 c$ ~9 r9 y
  [1 j7 s9 X$ l& ~
    set intersection? false
1 N' b, F6 ~' z8 b    set auto? false
3 l: Z+ e, |. N) `( P    set green-light-up? true6 m$ r7 F/ w+ G9 N  F; [8 n- j
    set my-row -1! p- A2 q4 J( \4 l
    set my-column -1- E7 A1 K& H7 m
    set my-phase -1
# g! {, z& ^# ~9 l    set pcolor brown + 3/ T; U7 y2 |6 H6 R
  ]7 \! J3 O( X+ r& _. A/ O

+ a, V8 k& ~% L; S7 a8 @* k( T3 h) C  ;; initialize the global variables that hold patch agentsets8 k# E5 C* J2 {" }6 ]: F
  set roads patches with) C  A  w7 ?1 v8 ~3 O" h$ c4 m8 I
    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) or
, ^1 f# [( B* b* `    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]" b& W' C. N0 t# M5 \  ~2 |' z
  set intersections roads with
+ d3 _1 M0 H+ C. U, K: t    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) and5 O0 y9 N2 Q5 p2 J! p5 X
    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]
. Z3 {' x3 v- X8 V  r, S
( j  ?$ v6 {- S: J  ask roads [ set pcolor white ]1 e+ _8 B' t3 y3 o, b
    setup-intersections
! P0 ?+ b4 i' \* Qend6 \& l0 R* Q2 F" J
其中定义道路的句子,如下所示,是什么意思啊?$ T, T& e3 w$ {1 J, Z
set roads patches with
# [4 M0 n. c1 U, N4 n    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) or4 F1 i' M( E) b+ E# S# s
    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]1 R7 h6 H7 k  a8 l
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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