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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。! Y3 P# B4 @& e( _# d! n* u, Y
netlogo自带的social science--traffic grid这一例子当中,. Q5 U" B9 k6 }8 e
globals( P" B9 Q; a) v- K2 B
[6 q$ o1 s3 V; Z8 I, Y
  grid-x-inc               ;; the amount of patches in between two roads in the x direction
5 A) V* v- q& k% P7 D  grid-y-inc               ;; the amount of patches in between two roads in the y direction
+ v+ F4 P: o9 E6 {) d: P$ L, f  acceleration             ;; the constant that controls how much a car speeds up or slows down by if, o0 F. P; `( l. }& w' g
                           ;; it is to accelerate or decelerate0 X! P: d) r2 ^: G+ r* O  _
  phase                    ;; keeps track of the phase; {5 H& ]3 \3 Q
  num-cars-stopped         ;; the number of cars that are stopped during a single pass thru the go procedure
, B( b' I' V2 [; G8 ]) }: Z$ V  current-light            ;; the currently selected light# ^. E7 R- ]. C& K; Y" d
) R8 N  n5 V% i; B2 ^. N( B
  ;; patch agentsets
+ D0 z/ B8 f# p# k0 a. M) X' z& u  intersections ;; agentset containing the patches that are intersections# h; R* b. M$ i2 b8 E9 F5 v# ?
  roads         ;; agentset containing the patches that are roads
! y4 X% Y* `# ^& d: Q]
5 I9 @) E3 l2 z1 H3 R# E$ d$ d
8 Y7 f0 t  O3 n6 ?turtles-own& e. x- B# V& [
[
% `2 J8 u* w; {  Y& U3 O& [  speed     ;; the speed of the turtle2 w: F# [* I* P2 V
  up-car?   ;; true if the turtle moves downwards and false if it moves to the right
1 Z7 X/ p1 w" C2 q  wait-time ;; the amount of time since the last time a turtle has moved
! ~3 _5 ^9 U2 _5 o* e* |]! ^  T  a# U$ ~6 r+ B& J- C

7 K  e% _8 j2 z# c2 h" Jpatches-own$ m$ H) x; N% b, e
[. r4 d- f$ L( b* u) A# h. G
  intersection?   ;; true if the patch is at the intersection of two roads
9 X" d5 ?" S  b2 {& |  green-light-up? ;; true if the green light is above the intersection.  otherwise, false.+ Z5 G0 V9 ]0 S) o
                  ;; false for a non-intersection patches.
. {/ `: E3 B0 L8 j; ]! n  my-row          ;; the row of the intersection counting from the upper left corner of the4 `' D$ S/ Q+ u' C8 ]7 z
                  ;; world.  -1 for non-intersection patches.
( a$ W$ S2 W* E; Z- P  my-column       ;; the column of the intersection counting from the upper left corner of the$ j. J# d$ x% w8 }8 d+ I: Y
                  ;; world.  -1 for non-intersection patches.
9 S- ?8 j# @, c  M% l- {% H: q  my-phase        ;; the phase for the intersection.  -1 for non-intersection patches.2 L4 M5 D& A! i1 \- U& A3 f; R
  auto?           ;; whether or not this intersection will switch automatically.
' {1 U+ @$ R" R% g- v                  ;; false for non-intersection patches.
7 M( e4 A& w9 a* n5 s]
7 c% R( E+ h5 R( V' Z. _& c. I, C3 L$ I, k

3 W/ o$ b; z2 K  e; X5 M;;;;;;;;;;;;;;;;;;;;;;6 C# [' Q- z- u8 D$ T8 ]
;; Setup Procedures ;;" W; v$ L$ q* v9 K, I! z( H% ?
;;;;;;;;;;;;;;;;;;;;;;8 c  {  j& b0 O. w9 q

# V0 M! h1 e# O$ b5 i) l% g;; Initialize the display by giving the global and patch variables initial values.9 T* H$ y+ N0 _  _, y
;; Create num-cars of turtles if there are enough road patches for one turtle to" p  H7 p4 I& D9 y6 Y
;; be created per road patch. Set up the plots.
5 _* s4 x# p- a7 P- i) T+ _/ ato setup$ |. D" d% W7 ]: M$ q# j! t
  ca
1 j( _: x$ s+ Y1 r  J* U9 a2 I5 h  setup-globals
* l; Y% u4 V6 h" R! H6 F, k" t
6 C& b# {$ c3 A3 ]  O+ ~! P  ;; First we ask the patches to draw themselves and set up a few variables" v( }2 J6 d. R
  setup-patches
! i/ C6 O: W' I. a' C* d' y1 K  make-current one-of intersections( G# X/ {# m0 ~1 p# ~0 e4 c3 r
  label-current
1 L  r3 G0 g6 ]) r# i5 |& v: }$ _% a  t) B( n. ]& M! r
  set-default-shape turtles "car"
, y4 O3 x8 ]4 W5 n" g2 q
1 `+ D+ G8 N; M' r/ `  if (num-cars > count roads)2 P3 o8 g& ^2 K+ C* F3 _9 k
  [5 ]7 P+ t& n6 L
    user-message (word "There are too many cars for the amount of ". R+ p2 \! L$ M" x3 }; r
                       "road.  Either increase the amount of roads "
/ R" b# @2 g7 N( Z4 A/ q% H                       "by increasing the GRID-SIZE-X or "5 ^" p' g& c) X/ X
                       "GRID-SIZE-Y sliders, or decrease the "' {$ ^  V0 U+ h+ t" {% U, {
                       "number of cars by lowering the NUMBER slider.\n"- s( O0 P/ O4 W
                       "The setup has stopped.")
6 R+ Z$ U; c( W' }7 w" V8 ?; \    stop
0 e. Q9 j: h- P/ y  ]" P7 O' v7 G# v  W2 @

  U( l+ k4 W/ C) a' i& R( z  ;; Now create the turtles and have each created turtle call the functions setup-cars and set-car-color; U$ I5 j8 `1 d# `8 x- O
  crt num-cars- Y- r5 R* f- m1 i7 U1 _4 ?
  [
+ T' Q% r+ S) J, G: P2 \    setup-cars5 K& }4 Q2 O8 R/ f3 E6 n
    set-car-color
& ?7 G  P  G/ Q    record-data# t* ]  R: \3 `$ v/ q' q
  ]
& v4 ?) Q/ z1 M0 }: {% N0 s* z; B" c* i
2 E* z% q/ q0 u. P% w  ;; give the turtles an initial speed
* p2 _" W% @* A5 g  ask turtles [ set-car-speed ]
. S0 A/ v& m" w) s7 h8 C: Q
6 N; l0 M" A4 Z! M  reset-ticks  g% Y! Y% c: |/ w$ J! Y- B
end
) {" t  h$ g3 y4 m! U. J1 Y
; S6 t7 X& a: E- I  z) m" u;; Initialize the global variables to appropriate values
: y2 r+ P9 @* l" G: |7 qto setup-globals
( q2 |( z3 f: p+ L: ~% o  set current-light nobody ;; just for now, since there are no lights yet
; X* D1 Q2 D: X# o% Q, R  set phase 0. ~& F7 A* ]) E: U) i3 v+ ]5 v
  set num-cars-stopped 0
  p3 _( x; `8 k# Z: n  set grid-x-inc world-width / grid-size-x- |$ X0 z# S, _+ k0 _* u
  set grid-y-inc world-height / grid-size-y
- _) ?! O& j) `2 F0 b$ q6 a  X* K
' U3 T: P$ g- ^  ;; don't make acceleration 0.1 since we could get a rounding error and end up on a patch boundary
; H, o- i8 n8 ?# V6 I4 Y  set acceleration 0.0993 u, o* k/ b1 x
end
6 c  n* {; c, S  k3 r! U! @
$ @% h) E' T2 H) Q9 v* C;; Make the patches have appropriate colors, set up the roads and intersections agentsets," W8 x0 f" d- F* H
;; and initialize the traffic lights to one setting6 q: j+ K. f' c8 l' T$ w5 f8 f
to setup-patches
" e) Z5 x7 a7 v) l  ;; initialize the patch-owned variables and color the patches to a base-color6 q! `1 _( r3 I2 f& i  k* s3 Z
  ask patches* [. w9 x6 m) g; W6 [
  [# K, s* H6 `. j$ T' R! ?
    set intersection? false+ K1 Q9 }2 v% C1 f
    set auto? false
5 e' W/ |; B( M+ F    set green-light-up? true$ Y% q* ~' `2 d$ x/ W, D
    set my-row -18 J9 R2 D) T. ]
    set my-column -1, l" ~. _& Y. r
    set my-phase -1
8 E# A# S; A) |2 ]6 ~. h# Z5 k9 w    set pcolor brown + 3
  r2 y8 w2 m- O  I7 t) O  ]
9 c( |9 [/ h, e/ F, Q, l: w& O4 e0 m3 H3 t
  ;; initialize the global variables that hold patch agentsets) Q6 [, l/ D9 F5 L6 x
  set roads patches with
9 z2 X6 e7 Q- @; B1 q7 u4 ?    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) or) ^" E4 n7 v# Z/ q- {
    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]. l8 ?5 x2 F% d
  set intersections roads with* C" i! m0 q6 {8 J. e1 C) _  K$ _
    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) and) ^# A! d; X2 v1 O; v9 n' E
    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]0 P, \, P  i: B0 Y7 ]8 @

+ S! j7 J: I% \6 a( K+ z) h  ask roads [ set pcolor white ]
% d% T$ U& f9 }$ \    setup-intersections
7 M6 U* q  H3 ^/ @- Wend2 {# L' u: W  M" v- P
其中定义道路的句子,如下所示,是什么意思啊?) p- A% u8 ?- K/ j
set roads patches with
& X5 s; b+ M7 Y! {7 K9 k    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) or
* [. E; f) G) J- q8 j" A# b    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]& r9 T. H  l2 k; p5 H
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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