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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。: x3 i/ B+ J* W" G
netlogo自带的social science--traffic grid这一例子当中,
4 a7 `% t  l3 Z+ `9 c+ O, pglobals! i8 [1 {+ c- l3 f
[' M" w& }' T4 E7 m: V
  grid-x-inc               ;; the amount of patches in between two roads in the x direction
6 @  ?$ ~; J0 R$ o: I. O4 D" [. s  grid-y-inc               ;; the amount of patches in between two roads in the y direction
+ K4 X3 z( E& y3 X" `6 o/ B" Y  acceleration             ;; the constant that controls how much a car speeds up or slows down by if
$ N& _. r6 A$ }" R, j! S7 h                           ;; it is to accelerate or decelerate
4 T: a( _9 B+ ?; a2 P  phase                    ;; keeps track of the phase9 b1 _- k/ b1 u* @0 Z
  num-cars-stopped         ;; the number of cars that are stopped during a single pass thru the go procedure
, V9 U  X6 a. U# ]3 I  current-light            ;; the currently selected light& U% f& i4 Y# x

6 A; u% e% a. Q* e0 [  ;; patch agentsets
5 K8 d+ o6 u# {" T  intersections ;; agentset containing the patches that are intersections0 P) F/ _3 n$ {5 g6 j
  roads         ;; agentset containing the patches that are roads
1 D% J: Z6 Y/ _$ z4 N* R' [2 d]9 {& ?& S5 [6 z' o: m" ~/ E5 _
: K5 X+ a' v# O9 }( {
turtles-own) Z( f9 L0 t6 O7 f5 i4 {( x; g- H
[
( u8 M) W' e0 T  speed     ;; the speed of the turtle4 Y8 _) G0 c9 q1 W
  up-car?   ;; true if the turtle moves downwards and false if it moves to the right
5 ?7 M8 k0 E, I" A+ k, o& m0 z+ ~  wait-time ;; the amount of time since the last time a turtle has moved
. F  `$ l5 A/ F- b% i& o5 T]
( d, I( r: C, ]8 S
/ N8 `6 `' D' s. qpatches-own
* K, r0 i) c" M2 O$ Z[7 f: Z% t8 E) S7 Z) B
  intersection?   ;; true if the patch is at the intersection of two roads
5 V/ U. f% O1 R% m! W  green-light-up? ;; true if the green light is above the intersection.  otherwise, false.5 B" H4 Z& J& g- ~, `; U
                  ;; false for a non-intersection patches.* e$ _/ t' [( ~" O% I$ K1 k4 H
  my-row          ;; the row of the intersection counting from the upper left corner of the
5 K  b: W( M, i& g. Z                  ;; world.  -1 for non-intersection patches.
5 r) X# H+ q! D& X& \  my-column       ;; the column of the intersection counting from the upper left corner of the6 d. g% o7 r% e0 V; q
                  ;; world.  -1 for non-intersection patches.# Z$ J- @7 ]8 W, `
  my-phase        ;; the phase for the intersection.  -1 for non-intersection patches.
- v# g9 `% q$ o. t% e  auto?           ;; whether or not this intersection will switch automatically.3 _. C. c% x7 B4 u- S: X. ^
                  ;; false for non-intersection patches.
* E: [$ f) r  {( j7 l9 L  A3 y& t]: i% A% f. y9 L: Q
% Q& {2 c1 i! _& Q# e9 t
' T8 p8 I' t( b/ G, g2 o
;;;;;;;;;;;;;;;;;;;;;;) [8 h. c8 f9 A5 j0 C: x4 V5 d
;; Setup Procedures ;;
! j$ D9 L5 ?* O( A* Q5 l;;;;;;;;;;;;;;;;;;;;;;
) m/ [: |& ~6 _  I" x5 ]9 l: |: G. p+ x! y& g2 K
;; Initialize the display by giving the global and patch variables initial values.! D; O0 h8 Z, N& d2 z4 q0 I
;; Create num-cars of turtles if there are enough road patches for one turtle to* ~  f0 M. R% X& R+ J
;; be created per road patch. Set up the plots.
: b6 R2 W. t* o4 J/ }to setup+ F7 f; G1 C; n# v  w/ U
  ca9 \' @  @9 k" z
  setup-globals
- q3 v$ r: d( @$ ?- ~) I" d$ a* ]6 t8 B% t. z( i( k' @
  ;; First we ask the patches to draw themselves and set up a few variables- y/ i% h$ ~0 A/ p5 ?
  setup-patches
: G4 G* G" o8 H  m/ O  make-current one-of intersections- ?% W. \# x' h- V8 y# ~
  label-current
6 D5 V" H* ^8 g4 s" U! c* @  |$ X7 S2 L
  set-default-shape turtles "car"7 ]$ m, }! n' N) u& [7 {7 q

5 c2 h5 Y8 I2 Y% I. i  if (num-cars > count roads)& D6 K) R2 M+ r6 _  J' D. y: p
  [# n* l' G' Q- p+ f) x' L. q
    user-message (word "There are too many cars for the amount of "
) Y7 B1 \8 `! V                       "road.  Either increase the amount of roads "6 a0 z/ B7 h6 \  O" |2 W# Y) n
                       "by increasing the GRID-SIZE-X or "" l- C( k( w& p* p; q7 v
                       "GRID-SIZE-Y sliders, or decrease the "
: n. l! C, @' a8 p                       "number of cars by lowering the NUMBER slider.\n"$ N2 J8 }( w6 J
                       "The setup has stopped.")
. r8 @0 M* G8 S) }% Q    stop
) L0 O) {2 r0 X6 \% O  ]
* c( F5 p& C' c7 R1 R, b+ ^; R) C7 K8 n9 b3 ^# v
  ;; Now create the turtles and have each created turtle call the functions setup-cars and set-car-color
: }0 g) L) W- u% H. X9 A. e$ a0 z  crt num-cars) ~" D; K3 Y3 Z) d. y7 d
  [3 j( o& g! X* f, d0 }
    setup-cars
0 H- ^8 n* T( I+ r, N  S: e    set-car-color
$ ?6 u: {/ _: G; t$ u8 J6 u6 n  V    record-data
$ E  r& b/ i  E& p! l  B* m  ]5 U4 e  h/ E! k
0 C* W' e* c1 i6 B; G1 M
  ;; give the turtles an initial speed8 G7 L6 _  I. l0 t: n) D
  ask turtles [ set-car-speed ]( r# m& Y% L5 O& y4 }# Q! ~, Q

" U1 O* z0 }1 D4 |" {" E* m  reset-ticks3 k) z; a1 i' a; o3 f
end
% U) ~9 l9 `0 Y4 ^7 ?' W
" Z- @8 |3 ]1 V$ f1 y! |;; Initialize the global variables to appropriate values
& |4 h- u+ P- O5 fto setup-globals
. {: V4 Q* y. N" d4 {- t9 i  set current-light nobody ;; just for now, since there are no lights yet% ~" a+ Y' F+ ?2 R6 F" d$ J3 V4 h
  set phase 0
  m! ~- l9 J! e+ H  set num-cars-stopped 0
" S+ Z! z1 _3 X' p% R% ?" e  set grid-x-inc world-width / grid-size-x  h* l; t" I* G% P
  set grid-y-inc world-height / grid-size-y: G2 ~" H* t  \) k. u9 {0 ?
/ p' J" e2 y8 w# P  t
  ;; don't make acceleration 0.1 since we could get a rounding error and end up on a patch boundary
2 c  Y4 B' b! v0 y" }( a  set acceleration 0.099' L6 O' u! A' s& [3 r) r3 J
end- f, O/ h; |$ X" Y6 l

- h( ~* e; P9 I5 c8 S;; Make the patches have appropriate colors, set up the roads and intersections agentsets,
7 J6 C# H) N; z( e  f" M;; and initialize the traffic lights to one setting1 q! t- k+ O) J+ K) ?* A
to setup-patches4 \  i' A$ }- M7 S3 f+ {( B5 }
  ;; initialize the patch-owned variables and color the patches to a base-color3 I* q; D) O9 \  d, C! H' Q( R
  ask patches
8 U/ X6 `1 {7 v% Z& S  [2 t1 K# o# `' L: j: j$ m1 v7 t$ i
    set intersection? false
: c, m+ W6 j: y- X3 F    set auto? false
% f! Q, u3 G# L0 v2 g) e7 ~5 [    set green-light-up? true
6 a' K* k  @1 q. ]) }" Q    set my-row -1
+ l9 Z2 E, S' _9 q2 V    set my-column -1
# _/ Q2 c7 [% U' o6 }2 @5 D    set my-phase -1* ?( z2 S$ ~% K  ?- \
    set pcolor brown + 3
8 F5 w8 k( f- k" N  K# r/ v  ]
1 _2 R: x, _0 g6 ^2 m! b! @+ }' P9 R, o9 p
  ;; initialize the global variables that hold patch agentsets
2 J, O9 Q2 n7 a  o" N  set roads patches with
. p! M4 f' V1 ?# q. j9 d    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) or
! _3 d4 T4 \0 m  Z% u    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]
3 _6 G- ]/ {$ ~  set intersections roads with
3 A" f4 G2 h9 p* `    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) and
" J" ?6 M" I4 g    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]
% L0 j: \3 j. d0 ?. n8 a
: {5 o1 ]& d, i5 ~% B7 T, c  ask roads [ set pcolor white ]9 K+ U9 d% e% t: }9 d' N- L" }% F
    setup-intersections5 i% X/ O: j9 [; e* U# {5 \( N
end9 A0 n0 m- n/ M- M1 G
其中定义道路的句子,如下所示,是什么意思啊?  K$ J8 {% ^5 e- q- B0 x
set roads patches with% f  l& p; V- K1 W6 ^
    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) or
+ y  g2 `& w9 W3 Y    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]
; z2 ~, d' u# 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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