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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。4 E" J* C( Y; R- X* u- |' Q2 H
netlogo自带的social science--traffic grid这一例子当中,& f0 O- y1 x$ H+ v
globals
6 M7 p9 H6 y7 G$ h- }( W[
  {* i1 d  ?% [+ Y0 G7 j  grid-x-inc               ;; the amount of patches in between two roads in the x direction1 Q; |  @$ l% q# z
  grid-y-inc               ;; the amount of patches in between two roads in the y direction) M7 Z1 |2 {0 E' W7 n: b' \3 f1 k8 ^
  acceleration             ;; the constant that controls how much a car speeds up or slows down by if
, m" r7 N: |9 T+ T2 X4 Q3 q                           ;; it is to accelerate or decelerate
4 q# {) n; _( H) ^" U! O$ t  phase                    ;; keeps track of the phase
6 \* V* u& _, l  num-cars-stopped         ;; the number of cars that are stopped during a single pass thru the go procedure
. l2 k( f) O4 D) p  current-light            ;; the currently selected light1 d9 v* R& E  l, l2 _8 v
: C9 t, U* a2 A
  ;; patch agentsets
; @7 e- [. O% t' r5 h  intersections ;; agentset containing the patches that are intersections
  L6 ^- X  y: M  roads         ;; agentset containing the patches that are roads
' {% r; \5 r# a% p- G]9 f5 p! ]5 U# N2 N, {7 L9 t
. ]& e$ U3 c7 A1 o1 u. S" z) Y
turtles-own
8 l& E$ L7 L1 `' ~! d[
  \% `5 T! d# X) e- s: O6 N  speed     ;; the speed of the turtle& z$ `+ l$ k8 d3 ^% @
  up-car?   ;; true if the turtle moves downwards and false if it moves to the right
% R# h. q; {7 }- d3 X5 @  wait-time ;; the amount of time since the last time a turtle has moved: U# H% J' M8 S. Z- H
]
7 D! v/ W5 C9 k6 [) }: b8 j; x2 i
patches-own4 U- M7 L- V4 s4 @- i, m) u
[+ g, ?( L7 l. m
  intersection?   ;; true if the patch is at the intersection of two roads7 a. t% \8 V' e' @& z& k
  green-light-up? ;; true if the green light is above the intersection.  otherwise, false.
! A. F1 i; f! y( D                  ;; false for a non-intersection patches.
2 ^: t6 E0 `9 S) z$ ?  my-row          ;; the row of the intersection counting from the upper left corner of the* b" f3 I! U' X
                  ;; world.  -1 for non-intersection patches.
) _: ~& y$ w( C! \) B3 Z% B  my-column       ;; the column of the intersection counting from the upper left corner of the6 ^1 M: M4 y' h8 A9 C- d5 S9 f
                  ;; world.  -1 for non-intersection patches.
5 L6 Y1 b; I9 o( W1 E( }- L7 l  my-phase        ;; the phase for the intersection.  -1 for non-intersection patches.: q; U6 P& h6 ~
  auto?           ;; whether or not this intersection will switch automatically.7 `8 w& i8 z+ _) Y3 b
                  ;; false for non-intersection patches.2 H3 J, }' K" o# ]
]
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5 W' q7 B- ?, W) J+ o;;;;;;;;;;;;;;;;;;;;;;# E! c. n9 [2 r! P% O
;; Setup Procedures ;;  {0 d+ D- }0 h# B4 Z3 ^
;;;;;;;;;;;;;;;;;;;;;;
6 v9 J# W" G/ z% U3 E- l9 v: \! b8 R" h2 P
;; Initialize the display by giving the global and patch variables initial values.
* a0 C' H) `/ H' e$ N8 t- o' o;; Create num-cars of turtles if there are enough road patches for one turtle to3 e. u6 _" ]8 l# h
;; be created per road patch. Set up the plots.
; U+ p  J( {2 Y' D3 fto setup- `8 N9 X" h# Q3 m# Z7 `
  ca) n* t* Z1 c' E1 [* {+ ]
  setup-globals4 l- @; v7 O3 n4 F8 S) m, _" r# I- ?

4 Z7 o& y. M" ?3 Z1 R5 c  ;; First we ask the patches to draw themselves and set up a few variables
3 W2 F) x1 [2 I4 V  setup-patches' q. S, @6 t, a1 s
  make-current one-of intersections  b" r$ z5 [: t' W  N. W
  label-current$ w) ?5 a% t7 i6 v) a7 o

, F! _4 q' I; _  set-default-shape turtles "car"
3 M) j$ j0 H  W/ G
+ O! `. b6 `6 Q) P( ]' P3 P* \! B  if (num-cars > count roads)8 l7 x* K- C, r$ ~' D
  [! N3 F  d+ u( [$ H  y
    user-message (word "There are too many cars for the amount of "
' B# k3 g. U- O  J) i) V                       "road.  Either increase the amount of roads "
, N( d/ |' A( x/ D5 K                       "by increasing the GRID-SIZE-X or "
% n4 A- i0 ]- m) B5 I: B% D                       "GRID-SIZE-Y sliders, or decrease the "
1 O) ^# W4 l7 ~% b: E" h4 v- H                       "number of cars by lowering the NUMBER slider.\n"8 u  A5 n" u/ e9 f+ R  i
                       "The setup has stopped.")5 Z+ i  @! O! y7 d8 @
    stop
$ x- g. j* c2 w. g! V& ^. ]/ y  ]* y  b$ {$ j. w  H
, G* R6 r% |+ g, j! p
  ;; Now create the turtles and have each created turtle call the functions setup-cars and set-car-color
/ @4 ^- J  @4 w  crt num-cars0 s) ]2 y' j: S6 b/ _
  [
( N: T& w6 h2 D, Z$ w$ i. L7 K    setup-cars: {7 v$ o1 i) [$ e% q
    set-car-color& Y; ]9 D) O% d/ i$ q! G0 s7 ^6 \
    record-data* P4 C9 a: Y3 z6 x' H' r7 @
  ]& t: q! E- h) v" E2 q
/ h/ N5 ]& J0 v
  ;; give the turtles an initial speed8 K4 ^& a' J- Y* Q$ N: y; S
  ask turtles [ set-car-speed ]
$ g4 ^; P: e" o( T: X0 k2 |. `- i4 i1 {3 v( ^
  reset-ticks# s) [7 Z$ |6 ^" s( K4 r" c0 D& Y
end
' {! \9 U9 }0 }! ?1 p
, n, q1 Y$ @* d7 D, P;; Initialize the global variables to appropriate values* H9 P" j/ M' A0 ~
to setup-globals* `$ `7 t; v8 m9 J# v
  set current-light nobody ;; just for now, since there are no lights yet
& Q6 t! _- ]+ N7 h  set phase 0
4 u0 \# L8 Z/ _  V0 C( e" O* A" b! r  set num-cars-stopped 08 g) U+ G' O: q5 t% H! k: `
  set grid-x-inc world-width / grid-size-x3 s9 l2 a; Y9 ?1 l* D! a1 v& L% A
  set grid-y-inc world-height / grid-size-y* j( T: I0 A. \5 z

+ e( a2 F2 Q2 I; r& F  ;; don't make acceleration 0.1 since we could get a rounding error and end up on a patch boundary; Y% N* W+ Z; v) Z  E/ E
  set acceleration 0.0997 t' K; A6 G8 S
end* `4 o! X  u7 f
+ l" i" e9 ^' D( G7 z4 P$ R) s+ p
;; Make the patches have appropriate colors, set up the roads and intersections agentsets,
( t4 g# a7 N( g0 d;; and initialize the traffic lights to one setting
: F) H! k4 P1 J$ jto setup-patches2 Q, W7 i; I& M
  ;; initialize the patch-owned variables and color the patches to a base-color
" D9 P  L7 i) X: Z' U5 Z  ask patches
8 {2 T; O5 ^1 n9 @2 Q0 a3 f  [
: v- L' \2 U& d) p! ^    set intersection? false
; ?% S' Y3 u8 H  d% D    set auto? false
" q) e( Y* v% }. K    set green-light-up? true: B0 O0 K5 ?$ H: p1 H5 R# y
    set my-row -1' N- P  O0 H0 f6 K; `
    set my-column -1/ W9 ]2 p: l, h3 h* k; X
    set my-phase -1
/ x% o5 \! ~$ N4 X    set pcolor brown + 3
/ a# g: Y* p7 S0 d  ]
- `' `! ?3 J  Z0 D, G6 S
, Z2 B0 c' d3 x2 o, G% u7 Q# C  ;; initialize the global variables that hold patch agentsets2 u4 v  B, m# [/ {
  set roads patches with$ i9 s! z3 b, H3 y
    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) or  y: B5 }# m: ~# u: m6 A0 p; o# W& k+ {
    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]
- I3 j/ d' G! _  set intersections roads with
% n6 V' A0 l. ]2 x' x) z( d    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) and
( e3 `3 q, L) T: h# i    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]8 P" q# C/ }: p; S' |/ R1 B
9 D: B8 y1 D( ^. c! M9 Z
  ask roads [ set pcolor white ]
8 U# M2 k! S( n) I2 X2 M2 Q* P4 p    setup-intersections
, [% m% e4 u0 Z  Qend7 G+ j$ X) o/ f* M9 C0 G$ G4 A
其中定义道路的句子,如下所示,是什么意思啊?
9 f% r( d2 P- C& S* }5 D: \' z set roads patches with+ }/ @7 T1 x+ g/ K: N/ @
    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) or7 I( M" ~7 p- E  x  E% P
    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]
6 }" v+ j# Y2 G: D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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