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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。
( a- R% ^5 [# I' B$ vnetlogo自带的social science--traffic grid这一例子当中,4 h: u: m( G5 I9 n+ _6 a
globals
1 S# I: C0 u! x) @2 C0 ~) X[' n' M& ?0 p7 q. c$ E# a
  grid-x-inc               ;; the amount of patches in between two roads in the x direction6 }5 ?$ Z! O9 _& |8 m5 w/ o/ C
  grid-y-inc               ;; the amount of patches in between two roads in the y direction  d+ K; n5 R& E/ G9 ]
  acceleration             ;; the constant that controls how much a car speeds up or slows down by if8 Y+ }( E( S" p2 K
                           ;; it is to accelerate or decelerate- ^" _1 G& M: V% R# Y' L- [" [9 }% c
  phase                    ;; keeps track of the phase0 ^& U. i" y) r1 @
  num-cars-stopped         ;; the number of cars that are stopped during a single pass thru the go procedure$ t. U) |+ ]- G
  current-light            ;; the currently selected light
6 h/ ~- T: y; e% P! l1 C0 l, ~2 Z# b2 G$ o7 ^" e% K/ g/ s' h
  ;; patch agentsets
& v+ p  w9 f9 {5 l% f0 Y1 B" ]  intersections ;; agentset containing the patches that are intersections7 s. H# q. X/ L" c. D" I
  roads         ;; agentset containing the patches that are roads
# ^  A+ e+ _: l" M- a" c]
( U* P$ H( \8 c9 s4 h5 v* [
8 _0 G. X. d& [/ E0 a+ X6 a% Lturtles-own
, E1 E  |9 |8 ?3 e6 c[( c, G% o/ j$ P
  speed     ;; the speed of the turtle0 Q- D9 I+ w  L: \7 y' O" j& E
  up-car?   ;; true if the turtle moves downwards and false if it moves to the right- ^3 l* n$ Q* Z) W
  wait-time ;; the amount of time since the last time a turtle has moved
0 g2 H/ ?" Y: p: `$ I]. C& C7 U+ }) ~) M  W* I! H

/ r  s7 j) A* S- _( |  }patches-own
$ q" V2 M+ W" X: @5 ^[$ ?- ~/ ?9 p9 j' E" r; |. i0 v
  intersection?   ;; true if the patch is at the intersection of two roads
/ n1 F5 I7 B" ^" n; g  green-light-up? ;; true if the green light is above the intersection.  otherwise, false.
& J7 u! R' ]# h$ N+ h% c  B                  ;; false for a non-intersection patches.
* B1 G2 ^# i" X9 E# Z  my-row          ;; the row of the intersection counting from the upper left corner of the
! K6 ?/ }+ _! |* h# d3 Y, M                  ;; world.  -1 for non-intersection patches.
' {  }+ w( d! z6 k1 M  my-column       ;; the column of the intersection counting from the upper left corner of the
& \; r* Y& p6 c6 k6 o                  ;; world.  -1 for non-intersection patches.- ^/ b8 V. y- z- n, Y/ r
  my-phase        ;; the phase for the intersection.  -1 for non-intersection patches.1 b+ ?8 a$ R. a/ M
  auto?           ;; whether or not this intersection will switch automatically.
8 `+ D, {) P- @% [6 P! O0 d                  ;; false for non-intersection patches.8 }$ _3 }! w" d- ]- I
]
5 i, a$ {+ a* {) }( e; m6 Z6 ~, y% }& `
1 V& j  |' h. A0 i( _% f: {( b+ _: X
;;;;;;;;;;;;;;;;;;;;;;% I$ D! R; \$ ~6 G0 `, y& r/ V
;; Setup Procedures ;;4 C# [$ K* Y8 ~$ r7 l* s9 f
;;;;;;;;;;;;;;;;;;;;;;
9 Q" K. }" P0 b" K, x4 O+ t; a3 c8 H
;; Initialize the display by giving the global and patch variables initial values.8 j; K4 t5 ?; |9 D7 N
;; Create num-cars of turtles if there are enough road patches for one turtle to8 n5 H/ z; Y8 b. q8 m& M3 p& Z
;; be created per road patch. Set up the plots.
) p* _' n! }. k; R0 K- _to setup4 I  }# H$ [/ R) R- T4 y
  ca
: }; n1 M9 t" P8 `9 A! x  setup-globals
: V: t& l3 {+ S* q7 s6 ]
) ~' \8 m! s% k( O4 w5 S  ;; First we ask the patches to draw themselves and set up a few variables+ \; c) ?0 O# p
  setup-patches
- O/ ^9 g& s, X  make-current one-of intersections- v1 x% y1 _, [
  label-current8 t& {2 R9 S: ?7 M* }( H

2 @- l7 |6 k1 V  set-default-shape turtles "car"5 L$ S% ]' h# S( e% E' i7 `

) {/ k1 `* v, I* P9 Q* d  if (num-cars > count roads)* Q  v+ D' u$ m3 ^: s6 z+ i+ S
  [
7 U1 x: `- Y5 U+ w5 {    user-message (word "There are too many cars for the amount of "% d4 ]( n: C3 E6 f& \/ |, N& P
                       "road.  Either increase the amount of roads "
' h) c) W- b* K                       "by increasing the GRID-SIZE-X or "
2 Q$ y! ~0 b8 k* y                       "GRID-SIZE-Y sliders, or decrease the ". h) ~$ i3 T5 E3 D* Q) y. @
                       "number of cars by lowering the NUMBER slider.\n"
$ c  A. t9 d0 s) s1 H                       "The setup has stopped.")4 |8 t- u/ q; J- v
    stop! U7 j- l- w6 o& v& b" N
  ]2 C2 K3 |' A1 C
) F$ x2 R, v' ]; F- f2 [7 i
  ;; Now create the turtles and have each created turtle call the functions setup-cars and set-car-color
2 V" ]- h8 ?8 e2 ]  crt num-cars: x: n3 M. v$ O1 b2 l$ P: b
  [
! u! L& i" s$ c6 v2 z- @& X+ j9 q" z* q    setup-cars- k$ T# ?+ s! Q! ~$ F
    set-car-color# ]7 g" h" m+ ~! L; r* [
    record-data
$ {( u7 ~7 S# |7 [  ]* z$ w" b5 k9 X
4 L& F/ M6 \3 L
  ;; give the turtles an initial speed# }% s( O( @/ ], e# I9 m8 g( v
  ask turtles [ set-car-speed ]  \. {+ f8 i4 _( |5 s* M) B& t. {
/ i* T" f% I( _3 j
  reset-ticks% F6 s0 P3 Z. C
end
3 c  A/ z/ U- G0 N: ^
8 @0 q0 t# g% h% D$ i4 R3 T;; Initialize the global variables to appropriate values
/ f. R2 s% W8 xto setup-globals
  k6 r$ [4 l& X" a3 S/ T  set current-light nobody ;; just for now, since there are no lights yet
9 l: \, Z" T. n  set phase 0
+ T$ _/ T7 `9 f" ~) _$ @  set num-cars-stopped 0  f& Q1 l3 `) N8 Y( C6 `: q$ ^3 P
  set grid-x-inc world-width / grid-size-x" y, S4 c5 Z  V" P8 _$ _
  set grid-y-inc world-height / grid-size-y3 ?/ x( h7 Z5 M0 Z

# w0 g$ Y9 B( C8 p7 I: j6 Z/ F  ;; don't make acceleration 0.1 since we could get a rounding error and end up on a patch boundary
5 ~' u) J  S. b2 B  set acceleration 0.099
! _! p( p. t1 p7 O: A9 U# z! D6 |end* W6 K5 [% `/ J: o6 }2 a

# f7 c% Z+ b, M4 T;; Make the patches have appropriate colors, set up the roads and intersections agentsets,: a1 a0 ]0 P9 [
;; and initialize the traffic lights to one setting+ e. R+ D2 `6 z* [" M  r. H! F. |* m
to setup-patches4 a% j& f2 h" s3 y4 f
  ;; initialize the patch-owned variables and color the patches to a base-color
6 {  {0 X5 r. D5 I% l4 C" ^9 N) z" X  ask patches
: w. I! j3 {: |# ?0 x  [- `* o6 `5 r% H: |1 F
    set intersection? false
; }" K* V5 L% \+ U3 s* f    set auto? false* i) c1 Y) \$ O; b- C4 T9 j2 f
    set green-light-up? true
' f8 @9 }- P! [7 s; d    set my-row -1
2 q4 _8 v/ N4 j4 L6 U. l$ z9 e    set my-column -1
# j+ |" _! ~1 B8 Q    set my-phase -1
. N+ c% w( F9 ]& l- C* v4 v    set pcolor brown + 3; a0 J! A$ m: [' K9 n9 f2 N; x
  ]
' c' n" |: \% n$ z& z+ c$ D, w  R/ n" _  a
  ;; initialize the global variables that hold patch agentsets
) s; q9 ]3 i6 Q. `5 D2 e  set roads patches with
( l9 N4 U9 s8 J9 i$ q    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) or
) I+ V1 `' q9 B0 a    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]0 t* ^8 l" i* k, ^1 x
  set intersections roads with
# v6 T7 l6 O2 a0 I+ g$ M/ [# Y    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) and
6 _  V) ], O% h; J9 z1 S    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]
. a% y2 b: S- b$ w2 C2 ]- l. \- N4 o) @  s  \% O- {! Q
  ask roads [ set pcolor white ]3 ]6 b; }: M6 ~7 o$ I
    setup-intersections+ q/ s5 o5 P& K7 C# u& O
end
) k6 N; o6 R- I. G0 v' v, V0 M其中定义道路的句子,如下所示,是什么意思啊?
0 {# M2 A. S! p  b/ {4 t3 u9 @ set roads patches with
" U+ y( T1 T' ?$ W2 f    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) or
4 o- N& G8 L& w    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]# X1 [1 @! p" g- v& c
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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