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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。2 }1 x( i! k5 `6 y# t3 K' }3 m
netlogo自带的social science--traffic grid这一例子当中,
# u9 t4 b9 n0 ]  A9 n, e* Z* jglobals0 Z' B$ D& V6 b. [3 D! e& |
[# ]+ c' E' z7 I1 q9 e4 J
  grid-x-inc               ;; the amount of patches in between two roads in the x direction
6 z4 [, P% Z  ^  grid-y-inc               ;; the amount of patches in between two roads in the y direction% @  I; g# ^* I3 d1 ]' r6 t
  acceleration             ;; the constant that controls how much a car speeds up or slows down by if7 r! h! ^  Q- i2 I
                           ;; it is to accelerate or decelerate% Z; G4 z  t  y2 c: D% }
  phase                    ;; keeps track of the phase
! C7 D1 V2 C6 S* a* x2 k( R" e/ n0 W  num-cars-stopped         ;; the number of cars that are stopped during a single pass thru the go procedure( S% ~1 Q# W0 T( p8 m7 p0 R! z# Y7 @0 s
  current-light            ;; the currently selected light
$ {" K( F. Z2 f6 J* p8 X( T2 J$ y8 q- a/ V- `( T; L7 ]: M3 Q
  ;; patch agentsets
; Z8 l1 t. C! v- g1 b  intersections ;; agentset containing the patches that are intersections
) ], K) C3 q& E2 ^- K4 P; r7 N  roads         ;; agentset containing the patches that are roads
0 `$ E. W' ?' t+ C8 z/ c6 H]
1 }; U4 O4 a/ z5 }) q" k, [
$ J4 J, p2 j4 ~" Xturtles-own
) [# h. J  e& h$ T3 `[
# ~" c5 q. h# L. ~2 y6 i) |  speed     ;; the speed of the turtle
1 }/ ]9 O! l0 e. i4 g  up-car?   ;; true if the turtle moves downwards and false if it moves to the right' ^, t/ A" t: b% z4 L2 [! d3 K
  wait-time ;; the amount of time since the last time a turtle has moved! n6 B9 E9 p% K% M1 h1 o
]; [" x" Z5 v- f0 }
2 q1 b6 u9 k- A! F5 ?% A
patches-own
( o1 w' N8 c- ^! w' ]: t[- K  K' K2 h# e5 w$ ^: k6 }
  intersection?   ;; true if the patch is at the intersection of two roads
+ p! J& P( L, V, L  green-light-up? ;; true if the green light is above the intersection.  otherwise, false.0 P  r" k$ T$ Q, p$ s
                  ;; false for a non-intersection patches.* v9 a0 H" \) R6 T. Y. `
  my-row          ;; the row of the intersection counting from the upper left corner of the/ A' ]) b- C$ R
                  ;; world.  -1 for non-intersection patches.  ~' G: z2 ~7 K; z
  my-column       ;; the column of the intersection counting from the upper left corner of the9 L' G: @( b* n5 W- Z% ^# L# {. w( K
                  ;; world.  -1 for non-intersection patches.% L8 s6 U' U% I7 b
  my-phase        ;; the phase for the intersection.  -1 for non-intersection patches., R9 g3 M2 y  P5 x
  auto?           ;; whether or not this intersection will switch automatically./ N8 u/ S" \$ }  T) \! J  o
                  ;; false for non-intersection patches.
+ n( v. M+ J( p]  B  n. _: [9 Y, F+ }6 N+ W7 u  t

) _: {: E5 B: A0 m- o1 V, O+ E) K2 x' l% z! g$ n. J6 ^- P
;;;;;;;;;;;;;;;;;;;;;;7 Z; F" D) p3 n+ H/ P4 h8 |. S+ R
;; Setup Procedures ;;( o, t& V! K: t% U8 Y7 p, h
;;;;;;;;;;;;;;;;;;;;;;
, ]2 u& m: n2 F7 Q) k  O! K9 O9 f2 V1 r
;; Initialize the display by giving the global and patch variables initial values.
0 ]. Y) z6 Q) l* ?- K. S! ];; Create num-cars of turtles if there are enough road patches for one turtle to
/ L) Z/ g' b8 K3 n: P;; be created per road patch. Set up the plots.; y! w3 O$ j9 @9 Z# p  _0 D3 z* p
to setup; O3 h. w+ Z# O8 B* b% i
  ca
6 N5 t! g) w) P' y- [7 e6 i  setup-globals4 e# I! l2 [. {3 y

5 B& w: I2 j5 i) e0 C- ]) M! V" w5 |, v  ;; First we ask the patches to draw themselves and set up a few variables
7 D$ r0 D) Z- i, Z  setup-patches" M3 l& S" |3 t/ \! }: x
  make-current one-of intersections0 @3 Z) e8 L% k% \- w& B) O% N9 G
  label-current
' U4 @# S% v  c" V; b! f  c$ }  h' P5 w3 }% T
  set-default-shape turtles "car"
7 R4 @& m! C" \( J
6 M  @& S; R8 j0 C+ U* h  if (num-cars > count roads)3 ?( \" }+ m. ~: D8 M/ z+ a3 U
  [1 W) c, j0 G3 ]3 A2 K
    user-message (word "There are too many cars for the amount of "! x; l+ @5 f& ~/ o
                       "road.  Either increase the amount of roads "2 I! P; K3 ~# i& H6 e* U8 ^, \4 s
                       "by increasing the GRID-SIZE-X or "% A8 n, W' T7 N6 j6 i5 ]" z
                       "GRID-SIZE-Y sliders, or decrease the "
$ v7 q9 r2 _- T# Q; f7 c* _                       "number of cars by lowering the NUMBER slider.\n"5 U' N( l9 ^) [, t4 k; L0 ^) J& e
                       "The setup has stopped.")" P6 V% p0 w% ?
    stop% A* \. V0 P! F& \/ X4 [
  ]
4 F( @7 v0 [5 j% z
3 K; L6 H# g6 C0 O! a- l  ;; Now create the turtles and have each created turtle call the functions setup-cars and set-car-color
( S/ S! L; m% D4 Q& y1 W, H# f  crt num-cars
) |- O; p5 t; G) Q- U2 w' \, G8 Q* @" }) e  [
  c; P1 W% u! G# F7 l% `4 q* q    setup-cars
5 G: S: `1 O7 J  h, Z    set-car-color2 x8 {" a; y. e: [& P
    record-data  v  N8 R6 j$ _+ d" L
  ]
: O& \; X4 D6 W1 h9 o' y* D
+ _: @" F+ ?! b1 N  ;; give the turtles an initial speed
0 G! h6 _3 e& o; \& a( [) R% Q' O  ask turtles [ set-car-speed ], S$ F, q$ o& t2 \5 n  j  W8 [
" N4 m% w3 \9 ?. x" C9 A4 a; G
  reset-ticks
; v) L. V0 {$ O! U1 C+ Kend8 M2 z* W/ X3 z; Q4 t

, f7 {# e# _+ A3 a# Y3 j  P/ _;; Initialize the global variables to appropriate values( s: W. r- a- f: F% k# J) R
to setup-globals
! x# v7 w0 r6 }9 F6 @  set current-light nobody ;; just for now, since there are no lights yet
/ ?$ g! H2 Z: a/ _  o  set phase 0+ d4 ]% Z# U- ~% X; I- Q
  set num-cars-stopped 0
6 W/ y# f2 c: V' g  set grid-x-inc world-width / grid-size-x
- {: T% Q* k, z3 ?& j3 z0 N  set grid-y-inc world-height / grid-size-y
1 p6 I8 j) n# F' z1 `" V& S4 r, U' ~, X2 I. q& l
  ;; don't make acceleration 0.1 since we could get a rounding error and end up on a patch boundary' M4 U4 t& a' {( J9 J! v5 g: O
  set acceleration 0.099
3 n4 ]+ ^( _7 ~& @/ Q/ \  Fend
; Q4 _. q; F4 u7 S3 f
3 }$ u1 L2 L* J% b& Q;; Make the patches have appropriate colors, set up the roads and intersections agentsets,
; [0 i' J: {. B/ ~;; and initialize the traffic lights to one setting! m& m* w4 D; H8 q" @' |
to setup-patches
+ [' h2 g. U: W( m  ;; initialize the patch-owned variables and color the patches to a base-color( ?  _, l: w! D9 Q
  ask patches8 P. [% w' T, t6 `2 b8 @9 T7 _+ w
  [
7 v8 S& _  T  y! P6 x$ F    set intersection? false
7 S8 F! d0 ~5 Z8 g' I8 B    set auto? false+ g' A# H5 {1 {5 d, d' w# O# I8 Q9 z
    set green-light-up? true: n- \. b0 \3 X5 R% z! @! i
    set my-row -18 p- q" b. j7 K, T2 f) I
    set my-column -1# Z% a$ x7 B' K' o$ y. o
    set my-phase -1, J9 h( |5 b9 L2 [  r' H% b
    set pcolor brown + 3- L6 I! r( k& c# m- n8 j
  ]
4 x; Q( L+ K5 d( Y0 |! w0 ]% Q5 o0 M4 ~. o7 J, u. a
  ;; initialize the global variables that hold patch agentsets
& N4 ]4 D( C* |& S5 J3 v1 f  U  @  set roads patches with
( {8 v- `  K# q: H! d    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) or
) F5 u/ j! G/ n    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]& u3 z) ~  T( {+ p2 J9 _- E
  set intersections roads with  n$ o- f. J( e; [* X
    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) and/ o' E  V% d* [( }4 E. e
    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]  F. [1 ]# l& u& N' \

4 X. H; c- m% `4 J9 V. i/ m8 G, L5 D  ask roads [ set pcolor white ]4 }- a& j0 Q9 M& E' _- q2 C
    setup-intersections' I- `8 i; M1 y
end& ~7 [, j3 f2 K0 U: n6 p& ~, X
其中定义道路的句子,如下所示,是什么意思啊?
+ f3 a. ]( q4 ~6 q8 i  r/ d0 W set roads patches with  D. `& ?: Z1 g" K( C* L3 m
    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) or
, m/ D8 ^# D" \" f9 f4 H2 x0 J    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]' i8 O1 w5 ~8 H- U. V2 P
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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