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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。3 ?! y6 n: I" H
netlogo自带的social science--traffic grid这一例子当中,+ r- T0 n. S/ I& v( |- z2 D
globals
: l! ]1 ?3 W) I) C5 K[
2 n0 f) j9 m) y/ P/ ^  grid-x-inc               ;; the amount of patches in between two roads in the x direction
+ x6 e" x& Z/ |" W) g; g+ [# c  grid-y-inc               ;; the amount of patches in between two roads in the y direction0 x( E+ ]$ p( b% F4 G# q
  acceleration             ;; the constant that controls how much a car speeds up or slows down by if
( F8 E& \- n2 N# z& ^! i, G$ n8 z                           ;; it is to accelerate or decelerate
$ \9 o1 `. M' j% e. m3 a  phase                    ;; keeps track of the phase
% w5 q. s* C. Y' {0 p* P5 f  num-cars-stopped         ;; the number of cars that are stopped during a single pass thru the go procedure2 s* v6 W$ J2 i3 S  ]: t
  current-light            ;; the currently selected light
' {% |2 n  W/ ~- c$ n
: [) R. Z' `9 G  ;; patch agentsets( w* `8 }3 Y7 b4 S* r! r
  intersections ;; agentset containing the patches that are intersections
; L) M. N0 H7 G  X7 g  roads         ;; agentset containing the patches that are roads. a, F! t+ n4 d( H5 t
]. i4 \6 z/ Y6 Y# |7 T

% ~9 h; Q  P" ~) r% g# L0 wturtles-own
' L' z6 D$ \8 [0 w+ y) t) Z# J; D: F7 Q[8 d" r2 n) ~5 D2 b6 A
  speed     ;; the speed of the turtle7 l8 g2 R1 ]) ~
  up-car?   ;; true if the turtle moves downwards and false if it moves to the right' G: [+ H, k9 H3 c3 o9 U* e( s8 @! T
  wait-time ;; the amount of time since the last time a turtle has moved0 H/ R1 e; x- e0 N& |( `9 K/ y
]% c& F: j) X5 D9 i0 d, Y
4 j! x* u. _2 v! Q& i0 F
patches-own
  D) w, T# e" V+ g7 t4 X[
0 {" A( x- U2 s% G7 ]  intersection?   ;; true if the patch is at the intersection of two roads
& l! \& A, [1 u$ s  v5 a. G  green-light-up? ;; true if the green light is above the intersection.  otherwise, false.
- n( q1 y* \" l                  ;; false for a non-intersection patches.
. s0 d# |7 n+ v8 }0 h  my-row          ;; the row of the intersection counting from the upper left corner of the" K- i0 }1 h+ Y, y3 I
                  ;; world.  -1 for non-intersection patches.$ ]& R8 T  M8 z3 V* T2 \
  my-column       ;; the column of the intersection counting from the upper left corner of the8 ^  k& O& h) w- N; Q0 }* ]
                  ;; world.  -1 for non-intersection patches.+ y3 y# q' T. [. t0 Q3 ?# @4 }6 S
  my-phase        ;; the phase for the intersection.  -1 for non-intersection patches.6 ~0 r% j5 }  G( `* b" y/ d- A( w% `# O) R
  auto?           ;; whether or not this intersection will switch automatically.( U1 f2 [0 Z% u% |, Z
                  ;; false for non-intersection patches.
% m4 w5 Q# V0 e]5 n) S9 ?: w) A; Y$ s
" p* Q: h- V6 o1 p+ r% H$ }
" o/ J, O3 a# e( ~. M8 g5 K
;;;;;;;;;;;;;;;;;;;;;;
0 g/ H: c" }! [7 L;; Setup Procedures ;;$ b7 F, Y0 B/ P. I. i
;;;;;;;;;;;;;;;;;;;;;;- d% h; a1 {5 s2 n% E7 v& n

0 D( L. b5 M2 K7 d: u;; Initialize the display by giving the global and patch variables initial values.
5 A( v, H5 ]4 A8 U1 f;; Create num-cars of turtles if there are enough road patches for one turtle to* v5 q. X% V7 n$ E1 [+ W! T
;; be created per road patch. Set up the plots.
4 J  L; ^4 M1 @1 H; Ito setup5 Y5 R1 o7 O+ F! B1 j$ ~
  ca  L2 `* p, F, j
  setup-globals: M" P$ k) @7 [4 S  h4 n1 q1 R
7 X9 C# e* E) `  J/ u- x) E
  ;; First we ask the patches to draw themselves and set up a few variables3 M! Y/ q. X0 e) K
  setup-patches
# U5 J4 e( y2 ]6 R* q% W& S- [  make-current one-of intersections
, D+ D2 Y/ [: e& g' w6 L$ I# H: Y  label-current
' h9 f8 L  h# Z/ ]! J5 V6 T3 l7 B2 Q9 C! d
  set-default-shape turtles "car"
: U7 d  D- ]- c' b% _0 `# E" h' h% R8 ^+ _
  if (num-cars > count roads)
" P; d- {, N2 A# n0 o6 Z6 H  [5 Z) S8 W! X8 `) M0 u5 x% a; y$ J
    user-message (word "There are too many cars for the amount of "$ g1 l+ g/ S% f1 P1 [! L
                       "road.  Either increase the amount of roads "
4 @0 E  r5 e6 y& ^3 s$ H' @                       "by increasing the GRID-SIZE-X or "/ e9 @' o3 E. @
                       "GRID-SIZE-Y sliders, or decrease the "6 A* u1 T8 |" j1 q+ l
                       "number of cars by lowering the NUMBER slider.\n"
+ c. d9 R& m$ \: R7 x* p* T. a                       "The setup has stopped.")
8 ^. b3 e6 `. N8 W    stop  A, W; g5 H; y  L. v
  ]2 F% ]( ?" ~; _$ }, s* P& t

3 |1 V! a: f$ X6 N$ K  e  u  ;; Now create the turtles and have each created turtle call the functions setup-cars and set-car-color
7 n' ^7 S2 @; I+ }" i! @* A$ C& u  crt num-cars! D- S6 J) T; E- q3 i
  [
- A6 o$ W* P4 @. j; \$ o# _3 G, N    setup-cars
; a- C8 d7 D4 u: c    set-car-color# S+ g. X. ^2 Y( I3 H# E
    record-data
$ g1 a* g/ `$ B5 c  ]
$ B7 Z! _' a  ~# i( {% k, p
. Z7 A+ w* A* y; j* d  ;; give the turtles an initial speed/ R; Z+ z+ B* d9 p' y5 L
  ask turtles [ set-car-speed ]
& ^) N* k9 E' ]" B* A  O0 A. n5 n# ~( s- y4 L2 i
  reset-ticks9 H) _* t, A/ x; r0 G: F
end& \# r# ?: Q9 k, R' t

& F( x: }& H* [  j# f;; Initialize the global variables to appropriate values0 D! Z, i1 Z* y/ Z- b8 D5 Z+ x
to setup-globals
7 u( l% Q  A# f  U  set current-light nobody ;; just for now, since there are no lights yet2 U2 d/ J) W3 S% I
  set phase 0
2 D" x# c1 |/ f; ~  c& F! z  set num-cars-stopped 0
; n! \1 M4 E$ q/ W+ x' K5 r  set grid-x-inc world-width / grid-size-x, }6 v1 o6 w' F) Z
  set grid-y-inc world-height / grid-size-y
! [- U! B/ n8 H. W  ^2 D6 w- N, T
  ;; don't make acceleration 0.1 since we could get a rounding error and end up on a patch boundary
. H7 P( X! t& [( \  set acceleration 0.099
$ |& B  j7 p0 h. k9 nend
- E( X2 e# I) i6 Q( A( b
! M- X" ]- b6 O/ |0 f;; Make the patches have appropriate colors, set up the roads and intersections agentsets,$ p/ ~, _6 q! X+ [" x9 e
;; and initialize the traffic lights to one setting  ^4 q+ B! V' O+ Z/ m8 X! M9 M- S8 z
to setup-patches
  k: {6 b' E: Q& |  ;; initialize the patch-owned variables and color the patches to a base-color% s: I7 O3 U1 L, A, j1 h
  ask patches  T6 H1 w1 M4 W( ?
  [  E, v6 D% y6 `7 Q. k
    set intersection? false5 \0 U& J0 u& m2 r2 U3 k: S' T5 {  ?
    set auto? false
% m( r) j3 C6 C8 g$ W) X& b    set green-light-up? true
7 p: @, y( r: v3 K8 n) d7 I4 d, F    set my-row -1
! O; I5 z( n3 O! V0 K7 @    set my-column -1( X- i2 i0 L$ o7 a" T0 }
    set my-phase -10 J0 B5 l& X, P- ^9 \
    set pcolor brown + 3
" s) H5 }4 D# s6 i  ]1 \! C( b: Y$ M* X" ?% E
  M2 p+ f/ R; n7 W% ~2 o" N" l8 t
  ;; initialize the global variables that hold patch agentsets1 R- L' h& _' C1 y2 p, D
  set roads patches with
' u- c) [" [% L/ x8 x2 y+ l    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) or
* m9 B( r, `# x: U, h- E" ~    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]6 z8 e$ T" Z4 b! E' s
  set intersections roads with
1 i# E: g9 w! Z* Q' ~    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) and
$ i% ^1 w, U( n( @$ C    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]6 a8 b7 R' U( Z% _9 E" y
; {* D5 b' j; }' z' u1 f) W4 v
  ask roads [ set pcolor white ]! u# X' Y" w; V6 m* E
    setup-intersections
/ F6 i1 d- x# A5 f& Q4 j8 Wend
2 Z( G3 y- H  X8 e# d/ s其中定义道路的句子,如下所示,是什么意思啊?! g6 `" ^6 X4 q* o; p( Y/ n8 @$ k
set roads patches with
8 R6 t6 x; g0 m" W5 g    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) or& z3 `+ k' E: T$ c7 [7 _  }. _
    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]3 X6 _$ d+ C0 \
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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