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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。5 i( U- ^/ d- }2 @
netlogo自带的social science--traffic grid这一例子当中,5 H. a, X7 |* _# k9 W+ p7 \
globals
# L  k4 @. w* e. ^5 W. ^7 `[
( _& M9 R# a% y% R* s  grid-x-inc               ;; the amount of patches in between two roads in the x direction
7 U* @! _# I9 d5 ?" Y  grid-y-inc               ;; the amount of patches in between two roads in the y direction
  O2 u7 l1 F+ b) X/ Z4 E  acceleration             ;; the constant that controls how much a car speeds up or slows down by if6 R8 ?; F4 F; n* Y, i
                           ;; it is to accelerate or decelerate! {5 f3 b( x2 J+ V" b2 ~; T/ _5 f
  phase                    ;; keeps track of the phase  j2 c8 R% Q7 j! N6 `: \1 A
  num-cars-stopped         ;; the number of cars that are stopped during a single pass thru the go procedure
# s# z$ q5 N+ m6 i+ _2 Q  current-light            ;; the currently selected light& ^, c. W; d3 _7 ]& C! U! F

6 q8 N! m& o4 }7 A' O  ;; patch agentsets
: [+ g6 Q: `/ S' l4 b8 j4 @  intersections ;; agentset containing the patches that are intersections
1 B( P: N8 Z$ Y  w. p% s( A  roads         ;; agentset containing the patches that are roads
9 F2 K. q) ?  ~, A]
/ H7 N9 h8 U! s3 ]! d2 \+ \* I. `5 m
turtles-own
, a: c) W7 Y' W6 v[
1 h6 Q  J0 {, B+ v  speed     ;; the speed of the turtle
$ H! s1 `) P0 u* I& D% l5 c% f; o  up-car?   ;; true if the turtle moves downwards and false if it moves to the right& U8 b4 a$ @# m! S
  wait-time ;; the amount of time since the last time a turtle has moved
, v) D/ W3 e: f( F+ G# e]
2 h; i( ?8 Q4 w- H+ n6 V* K
  S; |3 R+ w7 v$ _patches-own" \) {; n1 w5 X& T' V1 M1 g. p( H
[9 g! F! J/ H- F# K% I' ?/ S
  intersection?   ;; true if the patch is at the intersection of two roads/ i, s8 {1 J' Q
  green-light-up? ;; true if the green light is above the intersection.  otherwise, false.
9 t* K( z$ f6 t6 O                  ;; false for a non-intersection patches.4 ~! B+ N2 C. j6 N. j' T: Q' C6 k8 C# @2 O: `
  my-row          ;; the row of the intersection counting from the upper left corner of the
1 Y+ ^1 b& d+ u+ \5 C) @                  ;; world.  -1 for non-intersection patches.# a% c+ X. a/ I9 A3 ^
  my-column       ;; the column of the intersection counting from the upper left corner of the
1 ~: R" l+ n; C- J/ x. w+ a6 q9 N                  ;; world.  -1 for non-intersection patches.0 K- a2 R; B$ S# r4 x
  my-phase        ;; the phase for the intersection.  -1 for non-intersection patches.! n) h/ A$ l* q" Y0 H7 Q
  auto?           ;; whether or not this intersection will switch automatically.
- X% B" A' Z% t( `4 P5 F- ^                  ;; false for non-intersection patches.5 i, o1 x) `' ~& {
]4 S6 h5 w' S( v0 M4 Q2 _6 x

6 _8 X& F5 @- j# g
; P2 P3 D, a" A;;;;;;;;;;;;;;;;;;;;;;1 O& r( j' A  s7 S( ]% C
;; Setup Procedures ;;
6 p0 a$ @4 U5 o# @% B1 `, J;;;;;;;;;;;;;;;;;;;;;;
" ^7 G  p7 |0 O  Z6 L$ b9 v( O" c  W! i
;; Initialize the display by giving the global and patch variables initial values.5 L6 R; T  G! s9 L8 u' U
;; Create num-cars of turtles if there are enough road patches for one turtle to4 u5 J3 m8 {- }$ \) U! J9 v
;; be created per road patch. Set up the plots./ X* N, C6 o- s9 U' j3 H
to setup
- j) r4 k. j8 `5 C. e- i( z9 V5 Z% N. S  ca
/ L2 i9 {* ^, R  setup-globals
+ l+ n9 y7 Z2 ~% k( }- G! V- {( u1 ~# d* G
  ;; First we ask the patches to draw themselves and set up a few variables
( S6 L0 f0 s& Q9 }3 S) M. r  setup-patches# }2 h& k, N! a0 j, [  n0 U% u
  make-current one-of intersections& s! u" {9 f5 w: C
  label-current( w2 x; {  I; L
! p( b% X9 ~+ G: ?6 [
  set-default-shape turtles "car"5 x$ K1 m* g2 o- h
  A/ I, U, n0 h, N1 j+ _; P- y! i
  if (num-cars > count roads)
7 g% T+ O! j0 P. H, x  [
  p3 q, ^% Z* l- ]. `8 R    user-message (word "There are too many cars for the amount of "
# O7 a6 r* e, t1 g1 C                       "road.  Either increase the amount of roads "
: X6 ^5 }$ H/ r% R1 E7 x6 w. \7 q                       "by increasing the GRID-SIZE-X or "
! v. U$ s  v+ u0 d4 a                       "GRID-SIZE-Y sliders, or decrease the "
+ ^& ?. v. W5 F+ J5 X. r                       "number of cars by lowering the NUMBER slider.\n"
! B+ w( [7 m7 u$ [                       "The setup has stopped.")
! U% W+ K: X. e    stop# |2 R/ a1 Y0 B# A0 S
  ]9 P4 y3 m% [  n) ?

7 ^1 L8 \" s7 h" l" Q6 c  ;; Now create the turtles and have each created turtle call the functions setup-cars and set-car-color
6 R) J9 _/ U9 G# x: y, }7 _  crt num-cars8 I% g; y+ \% S7 o/ X
  [
* q: C2 X* r9 o7 h! m    setup-cars7 ?! B* K. W) p+ F8 i2 S/ O
    set-car-color- ~6 C4 [2 h2 P
    record-data5 j% X& B8 X& P5 S2 o0 [7 i8 z
  ]1 c1 T7 L4 c) f1 a
. V* b2 k  U) {' u( Q: g1 k
  ;; give the turtles an initial speed
3 Q. u. u% R$ O) G4 T  ask turtles [ set-car-speed ]
4 s$ o) o4 Z' O* r2 y
, b- N& ^7 ~* p( D  reset-ticks
6 w3 _, ~" c- _% p* f  r7 Jend) Q$ B! y4 S8 |! q. s! e

  _4 ?$ L( @9 O4 x9 t  |6 R;; Initialize the global variables to appropriate values
( x0 O, O- L: Z2 D4 Qto setup-globals- @) K4 g0 \# i3 N2 [, K) |, X, Q
  set current-light nobody ;; just for now, since there are no lights yet+ s$ a+ w! ]3 v! Y
  set phase 0- K2 p5 T/ f  P2 R$ @3 A0 p
  set num-cars-stopped 08 }  s% R* T1 r( D$ ?% \
  set grid-x-inc world-width / grid-size-x
" r3 U# v! T$ }" K$ m+ L% J  set grid-y-inc world-height / grid-size-y
8 W+ Y) K  W9 h0 w4 r; d$ K/ H" o' y/ o( d( ?- P9 m( K
  ;; don't make acceleration 0.1 since we could get a rounding error and end up on a patch boundary
0 l! I; _# d7 e& i  set acceleration 0.0995 H$ s: n8 S" A' N4 E8 |+ _
end
2 G! Z4 r0 k# t% x  T0 N' e( G# m% E: B& c
;; Make the patches have appropriate colors, set up the roads and intersections agentsets,! t  k# y8 L# B8 Y7 d$ W1 j! M5 _. Z
;; and initialize the traffic lights to one setting& P6 m( m$ @! Z
to setup-patches
, T- o4 w) Y+ z" w: k) v! |# q3 F  ;; initialize the patch-owned variables and color the patches to a base-color; A) G- L+ m  [3 ?% \7 V: J* q- k5 W
  ask patches* @& |# x" e; x1 w5 R, H
  [
( Q7 S( I! W  x    set intersection? false
+ d( [$ h1 \7 f( d    set auto? false
2 R! ]9 e% w7 ~. T5 {    set green-light-up? true" W! Q2 u5 L4 s& |
    set my-row -1
( X6 f2 R7 A% C% j; I: |: S    set my-column -1
: o# B6 J' P$ v7 o  d/ \    set my-phase -1
) x, |6 C9 X+ f0 K. a    set pcolor brown + 3: p8 ]' d" _+ G" ?. a
  ]0 L% v2 I# M1 C! p6 n5 l7 A
5 U* Y7 ?# _9 B- S
  ;; initialize the global variables that hold patch agentsets9 z( k: q, N% R& v3 z) R" |4 ]
  set roads patches with
' T9 w9 W& ~0 L# v- _    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) or  J) a9 s# p7 F. a' _: V
    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]- Z4 C+ G. u) g: ]: v
  set intersections roads with/ X/ Y' G0 X  d1 ?8 W
    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) and9 v$ b. y0 c! K, U
    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]
4 Q/ i9 z) @9 u# q' p# x% F1 s* C8 B" _+ V" i
  ask roads [ set pcolor white ]
& H. n% w& Z; g8 Y% P3 w( l    setup-intersections$ T. b2 Z) M& l( Y
end$ b" _9 H6 ~) _4 J3 G& L
其中定义道路的句子,如下所示,是什么意思啊?
) }: Y/ B" a" |2 v: j set roads patches with
% g- J, r# `% ~1 i5 `" Y4 q) d+ S    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) or
( w5 y, }9 r. X0 \, h) J1 d0 a5 s/ C    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]: M# H6 h7 Z0 S% z6 q5 n7 b
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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