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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。7 n- ^2 t3 P: q! N: {! N
netlogo自带的social science--traffic grid这一例子当中,
' Q3 p3 O: O) m- A; \" lglobals
: s& Q0 S  C! S[
6 I$ K) X& @6 l. \6 V  grid-x-inc               ;; the amount of patches in between two roads in the x direction" C* _7 j! z2 b8 a& Q3 a
  grid-y-inc               ;; the amount of patches in between two roads in the y direction
* ?# i$ @! J* f: ?7 k, |4 V" T& G  acceleration             ;; the constant that controls how much a car speeds up or slows down by if
7 s  W  H/ Z2 h                           ;; it is to accelerate or decelerate
$ K" u1 j: {! I8 S# z1 m1 r& W( u9 ^  phase                    ;; keeps track of the phase
% w* B/ u9 A: g& @& {2 O  num-cars-stopped         ;; the number of cars that are stopped during a single pass thru the go procedure4 n6 ]7 O! O5 R9 x
  current-light            ;; the currently selected light
7 q# U/ I: d5 x( c" G1 y% V) W2 x
, R1 P' a  ?/ A- @  ;; patch agentsets
& }' t/ X% X1 C4 w  intersections ;; agentset containing the patches that are intersections3 D/ j4 P9 Z( B6 S7 D7 n
  roads         ;; agentset containing the patches that are roads! u7 O# h: k, _6 A- l
]1 Q- l$ c& B, y- K; Z
/ p: y  B$ C! W2 L6 s' x6 g
turtles-own) z; f& ]! I' L& t% J, x/ }8 ^. Q( D
[
. w4 p6 U( P& \0 f  speed     ;; the speed of the turtle
- m5 O7 V* u# w) ^3 A  up-car?   ;; true if the turtle moves downwards and false if it moves to the right* _* d7 a8 R" t3 Y
  wait-time ;; the amount of time since the last time a turtle has moved& G8 C4 L, V3 n. _  q; d
]
: u) j: U: D+ T3 F) k: V4 Z' W2 J$ t# q& B
patches-own8 L- o5 N# m8 |7 ?& t) S8 ?
[
4 e% g" t, F" s4 M" G* S$ ]1 W/ O  intersection?   ;; true if the patch is at the intersection of two roads* k) o7 ]) S/ L9 N
  green-light-up? ;; true if the green light is above the intersection.  otherwise, false.6 r& \$ b# j% {1 o5 z. d5 p
                  ;; false for a non-intersection patches.
; c! K/ h' Q0 `2 E" ]  my-row          ;; the row of the intersection counting from the upper left corner of the
9 I  o  r  L! i! L6 e. g8 @                  ;; world.  -1 for non-intersection patches.
/ n* B; w2 _1 D  my-column       ;; the column of the intersection counting from the upper left corner of the( Y, b6 S8 v5 _% H4 }; W
                  ;; world.  -1 for non-intersection patches.
4 W! q7 \6 ?- M, L" |( P: u  my-phase        ;; the phase for the intersection.  -1 for non-intersection patches.
2 @3 S1 d) a2 U1 Q  auto?           ;; whether or not this intersection will switch automatically.
% b1 J1 S0 y8 r                  ;; false for non-intersection patches." k5 u7 F8 A  b* n2 ]
]) P; G( b0 k9 d
  I5 O3 B9 S% W" p% _4 S

$ t6 V$ Q. J; U0 z;;;;;;;;;;;;;;;;;;;;;;+ ^  f; m3 [: q" [* e
;; Setup Procedures ;;) ~) D$ @3 e: ^
;;;;;;;;;;;;;;;;;;;;;;
! Y/ h. _8 t! u7 X: l
8 r' G6 j  E& \6 w$ f% s0 H5 `: S;; Initialize the display by giving the global and patch variables initial values.0 W, v( t. ^& h# r1 _7 h
;; Create num-cars of turtles if there are enough road patches for one turtle to6 J  z- |6 U- |: D, s
;; be created per road patch. Set up the plots.0 x: i0 E( h; [# b$ l7 b
to setup
" V1 M# C) I1 U& R  g  ca5 }, h+ j; O- b) @
  setup-globals+ i6 B1 S! A( V/ v

" I5 j+ c0 D, W  @2 q% B1 K  ;; First we ask the patches to draw themselves and set up a few variables2 d1 S6 U3 F( f0 G6 D
  setup-patches0 {7 z5 P: `, J8 o& V& b
  make-current one-of intersections
" d6 T1 w: R" s4 p, T# u  label-current
, [# D6 n6 {1 f4 u+ E( b* K- }4 \
3 [2 t* t9 n6 Y  E0 Z  set-default-shape turtles "car"1 K8 S/ h' h& z0 u7 E
: }. A7 B# G1 _
  if (num-cars > count roads)
8 Q2 b3 I/ q' U; x! _6 O  [
0 n8 f  F& y5 e, l( [    user-message (word "There are too many cars for the amount of "
, I8 c& {0 s: g8 ?5 G                       "road.  Either increase the amount of roads "
2 S/ e/ q/ F: B( g" \7 l& C                       "by increasing the GRID-SIZE-X or "
/ E8 d3 c3 c3 B4 S; S3 x                       "GRID-SIZE-Y sliders, or decrease the "6 Z5 p* G8 d, a# J8 _$ i6 L
                       "number of cars by lowering the NUMBER slider.\n"
1 H- o) j8 o3 Z( V                       "The setup has stopped.")
3 ]/ F2 `+ w7 d& U) c    stop
, C, V2 \- o! y  V6 A  ]  c+ _; D, T* e' q+ J+ h+ O1 L
3 m- f: ?" a3 ]; R  Z" P. i
  ;; Now create the turtles and have each created turtle call the functions setup-cars and set-car-color' ?5 A0 b% {3 U+ c1 h4 N
  crt num-cars4 w5 x& E8 X8 w' X  N# H
  [
$ {' W' |/ `3 u- N    setup-cars! O/ d1 N0 j4 m! D: f* I2 ?
    set-car-color, F& w8 r/ i- W5 f7 N& d
    record-data  C5 c& T* L: U/ Z0 V- u4 g
  ]# R% Y! f+ X, n5 W: L- b! Q1 s, Y" U7 ?

' S- K! C" i! d. v* B  ;; give the turtles an initial speed
. Y0 o  `. O4 ?+ T  ask turtles [ set-car-speed ]! |& d$ w! D; l8 u: ]
/ `: G& |& |" b* z
  reset-ticks6 Q. s3 u7 `) o4 D+ B8 n( D$ A
end
2 C& {+ e; q1 R+ D% c6 p) b  j+ ?- e" C  |0 o% h% @
;; Initialize the global variables to appropriate values
# C" K; E$ D( a3 O4 ato setup-globals4 s8 p: `2 I7 K; N( U3 m- `
  set current-light nobody ;; just for now, since there are no lights yet
2 Q) W; o+ {9 T0 p$ j7 y  set phase 0
+ k6 o- Q! w  K: _/ W$ K- _7 S1 v; z  set num-cars-stopped 04 Q; |8 u) }+ i6 q  ]1 D
  set grid-x-inc world-width / grid-size-x
9 [3 L1 m' W9 M4 r  set grid-y-inc world-height / grid-size-y' g8 Y( a( `6 T

  Z7 u  V7 R, m8 T$ @8 c0 n  ;; don't make acceleration 0.1 since we could get a rounding error and end up on a patch boundary) p4 V# z, X+ n' g
  set acceleration 0.099
$ W& U* O& G1 S" [' Send
# T% S( ?4 }% F. M8 F# Y) |. D/ \0 Z' B" j& ?
;; Make the patches have appropriate colors, set up the roads and intersections agentsets,/ e& n7 @; w0 }, ?% N3 G# Y
;; and initialize the traffic lights to one setting
, O, W0 a# A0 c1 x/ B: R/ w7 {to setup-patches
8 {' H9 E6 }. a6 w  N  ;; initialize the patch-owned variables and color the patches to a base-color! q1 C! v- p5 o% O% U0 u
  ask patches
) a! c% B% M1 T" Z: \  [7 ]9 `+ W- Y; ?6 G, `
    set intersection? false
" O* K+ c9 X. [* j' w/ O; S% Z+ x    set auto? false* D* R, x* H* |' I6 L- q0 T9 h
    set green-light-up? true
$ o+ j8 a& M/ G4 l    set my-row -1
: x0 b) ?/ c' k% Z/ E    set my-column -1
" g% K9 Q, g0 |* e    set my-phase -1
6 I$ X: }1 ^9 W& P5 d    set pcolor brown + 3" j1 v# W* |  v$ ]
  ]
9 f% r8 {- y( H+ p
5 |9 f6 \$ T" F& Y$ g3 o: _9 B  ;; initialize the global variables that hold patch agentsets! ?  }# {: p/ W( b0 Y
  set roads patches with
( x  [7 _; N1 S8 ~    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) or
. {* G9 a; z9 G" p    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]/ @1 w9 ?! F/ C0 C6 F( y
  set intersections roads with
) I1 b, E( L8 N5 U# |+ y    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) and
) o0 p9 ^( l7 ^: M0 J3 X+ i    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]
0 n/ j1 F0 z) z$ [' _* \1 X! g3 P9 S9 C2 A4 L
  ask roads [ set pcolor white ]0 N  p" U  H) K# ^* Q' C
    setup-intersections
/ ?! y' E9 L  D) d) |& v0 Kend
) w9 ]) s  }4 ~2 f其中定义道路的句子,如下所示,是什么意思啊?
5 z* c2 e" ]1 c set roads patches with
4 \3 x7 H6 e4 }8 R! c    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) or
+ ?8 F0 G6 A  Y# }    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]- g( o/ m  ]6 |0 V
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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