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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。: c4 q# Y  I; g2 H& n* A
netlogo自带的social science--traffic grid这一例子当中,
5 O" B$ P6 G, K2 Y( u& c: Dglobals7 W: ]( o* _) t; u
[/ A3 c. a1 l: K5 b  {
  grid-x-inc               ;; the amount of patches in between two roads in the x direction! {' c7 `1 h# @( J1 F- e
  grid-y-inc               ;; the amount of patches in between two roads in the y direction
1 u) [$ T, G3 J: m+ K  acceleration             ;; the constant that controls how much a car speeds up or slows down by if9 F, R$ I/ N- {( L1 I' e9 h
                           ;; it is to accelerate or decelerate- a0 Z: I/ P! r/ K  D) `
  phase                    ;; keeps track of the phase
( E$ s4 ~% T' X9 E  num-cars-stopped         ;; the number of cars that are stopped during a single pass thru the go procedure+ C* n% J4 B  v& s1 q* z; d
  current-light            ;; the currently selected light$ w' p. m& Z& `4 E! X
) p8 {6 V: n9 A) N' K% L  h/ W
  ;; patch agentsets
4 ^! \( l2 t* A- X  intersections ;; agentset containing the patches that are intersections3 v6 z, A3 m( J  D: E, c7 Q
  roads         ;; agentset containing the patches that are roads
8 [$ p  z7 ]5 y! W  Y]
2 @& Q( A2 z* }" f/ [6 ^( I2 o5 a% O, w* A9 Z6 B
turtles-own! w) A& D* v7 [; a7 P: x
[
6 c" _7 g& Y( a# W  speed     ;; the speed of the turtle3 }4 d, g& R2 K9 J$ p. V" n
  up-car?   ;; true if the turtle moves downwards and false if it moves to the right
: Q3 V; U/ p% l, o4 p( @6 }  wait-time ;; the amount of time since the last time a turtle has moved$ I% [$ d. v- }- @
]5 A1 X3 t0 @% g: d, B

0 ^. l. J9 i( t+ P! Jpatches-own
: f4 r( D( v" R( r- T1 ~+ U  r6 ^[
9 x8 R( `" [, G& v* o' `. f  intersection?   ;; true if the patch is at the intersection of two roads
+ K; l" S, X0 e7 V) B  green-light-up? ;; true if the green light is above the intersection.  otherwise, false.
4 l, B9 K; H) g5 G  A! D                  ;; false for a non-intersection patches.0 A/ i7 d( O4 |- n4 m4 q
  my-row          ;; the row of the intersection counting from the upper left corner of the
' H+ b4 F1 \( `2 Q                  ;; world.  -1 for non-intersection patches.% a6 n# j0 W, X( _+ x3 q
  my-column       ;; the column of the intersection counting from the upper left corner of the
1 m% V2 [0 j! ]$ o7 R( Y                  ;; world.  -1 for non-intersection patches.; A  I0 v/ A$ _2 ~9 p
  my-phase        ;; the phase for the intersection.  -1 for non-intersection patches.
# I! \. {6 X: l" q: b0 m  auto?           ;; whether or not this intersection will switch automatically.
& |! o" l$ ]2 N; @, f+ H& R                  ;; false for non-intersection patches.
/ a3 C, z( o' x, `4 n]  B7 `) f- H4 r- s* x$ v8 Z4 S

' v! q- G  m. @; b5 D0 C' P/ s5 I* C
;;;;;;;;;;;;;;;;;;;;;;
$ m% H1 b; Y( o& V, v9 O;; Setup Procedures ;;/ ^/ r# W* w7 X6 O; {
;;;;;;;;;;;;;;;;;;;;;;
( m% r+ o* p- i5 B6 f9 d% y2 [5 v& c* ]) ?9 U/ O. v1 I
;; Initialize the display by giving the global and patch variables initial values.
. {$ y3 t! Z. S;; Create num-cars of turtles if there are enough road patches for one turtle to
( [  _" i5 U4 ?: p;; be created per road patch. Set up the plots.  q+ ^% D9 H  z9 m6 X0 N
to setup
7 o4 J0 x% R: \3 z; S  ca
  O6 z, I8 H! [  setup-globals. G$ i/ R. w, z" ]

2 P  I9 X& s; i& z: d/ p  ;; First we ask the patches to draw themselves and set up a few variables& x* g/ Y% i1 r, H. C
  setup-patches
- R8 `5 f" v7 e& @. r4 u' A  make-current one-of intersections, n/ `# U3 s2 T6 P4 z1 F* L
  label-current
) E! c6 r! k& {9 D% ?, }, w5 {( R* R- E; C
  set-default-shape turtles "car"0 U8 L) X. C& V8 e1 Z  C
' A$ ?% n# |3 a3 _
  if (num-cars > count roads); U: Z! [0 E7 H- e
  [
7 g' i" n* r/ u; p    user-message (word "There are too many cars for the amount of "; v# M9 X0 O' o5 \2 X
                       "road.  Either increase the amount of roads ") L' Y0 \9 }& W; Z6 {' Z
                       "by increasing the GRID-SIZE-X or "7 j( k. n) b) Z0 T' R
                       "GRID-SIZE-Y sliders, or decrease the "  c5 m& L0 o" m2 G% e- M2 O+ G2 Y  h
                       "number of cars by lowering the NUMBER slider.\n"5 w3 I" W* T! ^7 ]0 l
                       "The setup has stopped.")) S, Z& Q4 V8 V/ }) G4 a3 z7 G
    stop
# C4 N. n1 e9 w: F$ {1 t  ]
; g, h4 i0 I! s* l
: B2 ^% a9 T; \" ~' e8 y5 p9 l0 l7 f  ;; Now create the turtles and have each created turtle call the functions setup-cars and set-car-color" N) y8 x+ n3 G2 M0 R
  crt num-cars
* I. J' d7 d+ |8 [& k7 B  [
% V, \* I3 ]! X  x, @. Z- P    setup-cars
1 u/ L/ T- o7 ]$ d- T    set-car-color, f( q1 @$ H7 M( }8 e) b$ |. U2 C
    record-data
- ~; S4 u6 j1 L0 F  ]/ E4 n! \) C9 g1 x! L; ?. u
" s$ v& J9 T, N# H. e, V
  ;; give the turtles an initial speed! A3 x7 a1 @: \- L. T- N
  ask turtles [ set-car-speed ]3 L6 q% Y; @3 D5 E

' e/ o9 d  m9 x+ n) B  reset-ticks
( m% b* `& n2 I7 d" Hend
# C: @, ?. q$ ^3 s0 y. N/ U( a
8 |( l% g" \9 H; b;; Initialize the global variables to appropriate values6 f6 R! a  _% M" r. ~
to setup-globals$ v3 k& P& G2 `4 P& W
  set current-light nobody ;; just for now, since there are no lights yet
% r- {1 }$ W( o  set phase 0% ^; [" x' d" Z* ?8 ?
  set num-cars-stopped 0
: F5 M3 u6 p3 t  set grid-x-inc world-width / grid-size-x  F. ]! Q" e; `3 b: V. ], z
  set grid-y-inc world-height / grid-size-y
$ g8 b6 P1 m$ Q$ K' W/ [
, L8 u6 z9 o6 }  m+ E  ;; don't make acceleration 0.1 since we could get a rounding error and end up on a patch boundary! D- h) \' c+ {+ p9 z! n; `& B+ Z
  set acceleration 0.0990 n9 j4 L4 D/ Z
end8 ]0 i3 l/ I: [" W5 H: O- O

7 P/ V2 h; a0 B;; Make the patches have appropriate colors, set up the roads and intersections agentsets,8 v, H/ `  `0 B: u& d  u3 ~& Q
;; and initialize the traffic lights to one setting
3 N1 |& ?7 P+ P4 N( F# K8 c- r) Uto setup-patches
$ G" s* Z7 L8 Y7 p  ;; initialize the patch-owned variables and color the patches to a base-color8 H, }; A9 }, G1 {  E4 n8 {
  ask patches4 c# K) W; t! Q. d2 z
  [& h! |% n# Q8 }' Q/ X* c4 x; M
    set intersection? false8 L6 W/ A- ~" P( |+ d8 d" p3 k* ~' u& q
    set auto? false
3 M$ T' n! T  t1 p( h$ g    set green-light-up? true; K- P7 _0 Z+ B' P: ^4 K6 A, Z
    set my-row -1+ f5 {0 {- N+ g5 p
    set my-column -1
( b7 A2 ?7 M4 S) N' t* g/ u    set my-phase -19 v/ ?% \  n# A$ d: _
    set pcolor brown + 31 L) d/ K. r9 r" N/ Q' B6 d" T
  ]- _3 S: z% U0 `/ ]1 W
9 b3 E7 V8 M5 ^/ j7 P! o
  ;; initialize the global variables that hold patch agentsets
9 b, x7 o  E/ c7 @* ~5 M  set roads patches with
; R2 t; }  q  V" e" p6 X& p( A    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) or' W; c4 O  F& M. C9 i, Z& z# {
    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]
" f- ^/ ~9 @& G2 G  set intersections roads with" b$ B  C. {. u0 z) V: d
    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) and, T+ ]2 D0 ~7 C- G' @
    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]  ]0 `, S  V* M3 @' x  H- z$ p; ?
( P& H+ w& U* C' q2 S5 _
  ask roads [ set pcolor white ]! G' H. ?$ w- w
    setup-intersections
! D8 W" r; a9 W) o3 zend
0 R6 w% G/ W* H2 p* u" D( K其中定义道路的句子,如下所示,是什么意思啊?
% H- E) C% p1 E set roads patches with
2 b5 s9 e! V3 x8 k    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) or- z7 O' Q4 X& s0 E3 \7 N# ^
    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]1 |+ v4 i! X7 ^' T5 W
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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