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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。
% Q4 z% m' R$ V) m. w3 ?netlogo自带的social science--traffic grid这一例子当中,' D* d+ W: l* X+ A2 u
globals3 o; B- A+ X2 i: M( ?! j
[, h# p( G8 q) Q  ]2 W: Y
  grid-x-inc               ;; the amount of patches in between two roads in the x direction5 ^/ Q5 b0 [9 A% t
  grid-y-inc               ;; the amount of patches in between two roads in the y direction7 w- o2 Q/ U2 o- N  [. _$ T6 l2 U
  acceleration             ;; the constant that controls how much a car speeds up or slows down by if7 x& a1 g  r; G
                           ;; it is to accelerate or decelerate
3 a( h) r8 Y, Z. I# F  phase                    ;; keeps track of the phase
+ V$ d+ U& I8 S  l6 N" n+ L# s% V  num-cars-stopped         ;; the number of cars that are stopped during a single pass thru the go procedure6 d5 S: S$ P( O1 Y
  current-light            ;; the currently selected light8 d% k+ R- h" J1 G( g

. z% g) v! P5 ~- |) S. t+ H  ;; patch agentsets& H: H" {9 }. n, o
  intersections ;; agentset containing the patches that are intersections
3 p9 t  F) K9 v+ x  roads         ;; agentset containing the patches that are roads
, S3 Q3 w/ j5 d$ []8 u* J" i. Z' e7 [- a# l

+ q- r0 _) ]. s! tturtles-own
7 T1 `) ~4 i) q4 }! p$ @[! l* K6 z3 |9 h1 P# Y
  speed     ;; the speed of the turtle0 M1 Y; K4 ?' X6 P. G. V
  up-car?   ;; true if the turtle moves downwards and false if it moves to the right" W* \) k, \% Y3 \$ q/ |& r, L; N$ d! d
  wait-time ;; the amount of time since the last time a turtle has moved( o8 O) _0 z4 w7 ^2 u
]
# Q' w4 @4 U6 @; Q2 h. K
  f% h% k- b% r" [patches-own
& J  W' G+ V- h" I& b6 ][; Q" p% e  M( I4 `* m8 h
  intersection?   ;; true if the patch is at the intersection of two roads
5 k& o8 P7 e& }2 |. L$ E  green-light-up? ;; true if the green light is above the intersection.  otherwise, false.- k8 Q2 c# Z9 X/ O# [
                  ;; false for a non-intersection patches.8 h. u* |  D- m7 m! ^
  my-row          ;; the row of the intersection counting from the upper left corner of the
! O) k" o( R: N3 n8 R3 ]3 a                  ;; world.  -1 for non-intersection patches.& G' `, A! t" ]8 J. R
  my-column       ;; the column of the intersection counting from the upper left corner of the
( a. q$ t3 z. F1 Z: f6 G' A5 g- u                  ;; world.  -1 for non-intersection patches.
& E0 M$ h! _" d" B  my-phase        ;; the phase for the intersection.  -1 for non-intersection patches.
% j  J' \! i# w' s  auto?           ;; whether or not this intersection will switch automatically.
7 _& e3 j$ D7 \: {                  ;; false for non-intersection patches.& ^9 N- P. T# A5 Y
]
0 i5 ~4 J- r9 @( a! [0 c$ G) Z; l" u. O' J& W" _5 D
. k  n; c( X' E
;;;;;;;;;;;;;;;;;;;;;;: o/ @1 b: m% ^5 V0 y: Y
;; Setup Procedures ;;
. E% i2 u+ w8 y' N1 _7 i! a/ Y9 f  {;;;;;;;;;;;;;;;;;;;;;;
: ?1 m: J+ |" R' v6 R3 \4 n! b7 }7 T  o" h* n0 b
;; Initialize the display by giving the global and patch variables initial values.
) H2 X* e+ ]" M& ]' a; e7 T) {;; Create num-cars of turtles if there are enough road patches for one turtle to
2 y) s! R$ J3 E% i- e! }9 c$ P;; be created per road patch. Set up the plots.
* p, D0 k" d$ j! F7 Gto setup
. k0 Q- y9 I4 _. i- t% z6 h' f  ca- \8 C: u9 a/ ]# J( L9 B% k1 s
  setup-globals
' z  P- ^" G/ D/ D4 Q7 ]/ A! B
! {) [) W- ~+ a: F4 O1 r6 d  ;; First we ask the patches to draw themselves and set up a few variables
3 L3 i7 H3 n8 h7 p  setup-patches
4 Y, @6 N4 V4 z$ \  make-current one-of intersections
4 h5 E9 c, O/ p: q5 d2 ^7 \  label-current! p6 Z2 T3 Y$ Q  h  Y0 |
( J  A2 Y+ J6 F& _: n/ P" H0 e! m' f
  set-default-shape turtles "car"
  r; W7 {! h3 T, G# P, g3 w* k
0 c# ~) W/ z' H3 U9 b) C3 O  if (num-cars > count roads)
* K: s& p/ ^3 h+ t# H  T$ Q+ X  [; C# g- ?. u  D, f
    user-message (word "There are too many cars for the amount of "
6 L4 }% ^% N9 r! ^                       "road.  Either increase the amount of roads "' u+ z" J# I* [2 t
                       "by increasing the GRID-SIZE-X or "
% T3 L3 p: @5 S: K3 N/ n# D7 g                       "GRID-SIZE-Y sliders, or decrease the "
, ^- D6 P! \; |% \$ h" g$ u3 P                       "number of cars by lowering the NUMBER slider.\n") K- y- E4 R3 \
                       "The setup has stopped.")' j8 X% U( |! ~2 ?& r
    stop% U6 p% E% Q( m2 _! U7 l( O
  ]
7 g2 L: U. g" e! v; O) D" m" s
# I: }: _/ r4 k* ^# P  ;; Now create the turtles and have each created turtle call the functions setup-cars and set-car-color1 j' _* V- R7 T% n3 c
  crt num-cars
( {9 B% N( @" d- Q* r, t! G  [
# R+ z  q# q8 `& n    setup-cars- U+ `# g( u' j# u
    set-car-color
& D5 q0 c! o! J" G    record-data- ~: ?3 I4 e& E6 u9 u
  ]4 X- ]/ f+ P1 }8 W
% n; ^, Z# p6 [4 o4 h2 n/ b, j
  ;; give the turtles an initial speed, k1 g  G  ]9 b5 \8 g
  ask turtles [ set-car-speed ]- t, \% N; k; _5 X5 ^
; h2 n. {/ C6 A; n+ ]* x8 T: p
  reset-ticks) ~# \0 b0 x  O" G7 g7 |. S
end
- ^. U1 X1 @: x0 ]
( h( p  a2 ~% O- m/ n;; Initialize the global variables to appropriate values# q' _4 N% t# i5 `) U  K: t7 C
to setup-globals
; q; O' J( o8 ?8 g5 U* _1 `  set current-light nobody ;; just for now, since there are no lights yet6 T) z' [2 ]6 a' h
  set phase 0
/ A$ M% J) x2 Y5 D, r& f' Z  set num-cars-stopped 0# K' P2 w* `4 k- G+ q
  set grid-x-inc world-width / grid-size-x" H( Y" g! O6 H
  set grid-y-inc world-height / grid-size-y* M: J$ j* B  J* a

' E( y. P6 I. J4 F0 {* l  ;; don't make acceleration 0.1 since we could get a rounding error and end up on a patch boundary
, Y4 {2 q2 O' h  set acceleration 0.099" y4 _( T, R$ o+ S( o7 j) h" V0 X
end
3 y7 K3 g7 f$ T& X, }3 K; w8 ^" ]% T; z, N: A5 H$ `1 I
;; Make the patches have appropriate colors, set up the roads and intersections agentsets,
2 \9 _4 Z: [# F! G;; and initialize the traffic lights to one setting# C, p- U% V0 {4 @- X! Q
to setup-patches: ?$ i( X0 Z( W4 {7 b
  ;; initialize the patch-owned variables and color the patches to a base-color
6 T& i, u! M& k  ask patches/ `. J; M4 \+ ~/ c& r; X
  [
/ R) _- _& d9 d5 ^3 J5 ?- @    set intersection? false" l# j% v3 _( S6 ]% N
    set auto? false: F) O' C7 @  I
    set green-light-up? true
5 t7 Z) B. Y* `. v    set my-row -1
4 `, ]2 q- h) Z# ^4 X    set my-column -1- d% F/ |/ ]9 a: ?
    set my-phase -1
5 n9 D' L5 I" y2 W# L    set pcolor brown + 3( B& f8 R7 t9 q
  ]
/ {; y# T1 ~8 X! m0 Q3 S3 a
/ n. E# G5 D" M7 |) j5 r" _: [  ;; initialize the global variables that hold patch agentsets
$ ?! y0 f( g) I7 L4 M- H7 g  set roads patches with' _% H, V2 R+ t- A- ^3 n1 `4 n
    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) or7 R% z3 |. U- t6 ^& Y
    (floor((pycor + max-pycor) mod grid-y-inc) = 0)], s3 V  `5 `2 _, Q6 b
  set intersections roads with
1 H: g- z) q6 j& [) f, s0 F    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) and9 U  j5 D6 [& \2 O9 K
    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]
# P& C) J0 ^: |8 D/ i: e6 i# C1 \: E, s7 n  ]; \
  ask roads [ set pcolor white ]2 a8 F+ S  Z5 ~9 q; I$ h) i" ]' M
    setup-intersections5 U% t8 ~; q2 b6 }2 i3 V) @9 K0 I
end
- T  ?6 W2 V" ]5 I其中定义道路的句子,如下所示,是什么意思啊?
# o/ r5 q. D& V$ N' J4 k set roads patches with1 h8 b5 ?9 r$ k6 U7 b& D$ N1 K
    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) or7 y% J) ?% Z' Y! W( V" L$ I" ~
    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]
$ T) J7 C+ D* u* R2 C  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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