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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。, ^+ C& M, A3 s8 u
netlogo自带的social science--traffic grid这一例子当中,4 e8 t9 R& A) S0 Y' p
globals
/ _$ h4 ~  Q( G2 |8 X[
, X# E% S; v) M5 s; i* U( b  grid-x-inc               ;; the amount of patches in between two roads in the x direction
; _- D/ Q# }$ s3 C3 [5 D: w# [  grid-y-inc               ;; the amount of patches in between two roads in the y direction$ S! r8 }1 l% I7 Y& ?- @
  acceleration             ;; the constant that controls how much a car speeds up or slows down by if
6 J  ~4 Z; G6 e6 e, M- s                           ;; it is to accelerate or decelerate
" @( w+ I6 J: O9 f  phase                    ;; keeps track of the phase
6 W8 r9 b7 C; t" N6 X  num-cars-stopped         ;; the number of cars that are stopped during a single pass thru the go procedure/ p4 |  Z  m  n' H6 S7 k' H
  current-light            ;; the currently selected light
% M7 H) P$ C0 _% O3 a3 i9 y! e, d' D6 n! P2 O
  ;; patch agentsets
8 Z" M+ l' O% b6 _9 d( D  intersections ;; agentset containing the patches that are intersections
& a8 E# ]; j' X) _) u$ {6 Q  roads         ;; agentset containing the patches that are roads& ]6 E( D7 c" _
]  `$ I& r6 C- w

# T" N1 j8 y9 R) \/ ~turtles-own
$ O, Z" X. {& m: D, B% b[, x. j. ^: W# b( m) J
  speed     ;; the speed of the turtle
2 z- Y# n; X# Y  up-car?   ;; true if the turtle moves downwards and false if it moves to the right- j; B0 M6 U  |* G) E
  wait-time ;; the amount of time since the last time a turtle has moved, B7 t8 }% {( F6 S2 f
]. P" p) h" `- q" ]- B" G" g
: j0 m7 N7 Z. r5 a# {# L# v
patches-own
3 u" \( C* I/ `2 Z" A4 C[5 k0 a' h! L) A- G
  intersection?   ;; true if the patch is at the intersection of two roads3 e9 u1 t6 l; ?6 S, S) F
  green-light-up? ;; true if the green light is above the intersection.  otherwise, false.* {2 z" D, E" T8 D9 Y! D
                  ;; false for a non-intersection patches.$ m: N( n; x9 E' A  G6 L
  my-row          ;; the row of the intersection counting from the upper left corner of the2 \% }# E3 S' W- K2 w# }
                  ;; world.  -1 for non-intersection patches.' j4 \( q5 d$ ^( x/ C
  my-column       ;; the column of the intersection counting from the upper left corner of the
  p% x9 L2 e3 \                  ;; world.  -1 for non-intersection patches.
2 ^6 f7 Y( h' T4 e* F, D# h( k  my-phase        ;; the phase for the intersection.  -1 for non-intersection patches.# Z) s# D) O9 k2 P$ i  _4 b
  auto?           ;; whether or not this intersection will switch automatically.
# I, d. N* A, l                  ;; false for non-intersection patches.+ A1 H3 ]- ~- T
]% H) j" `8 A* ~" q& K# c

9 u5 F" j1 Y2 j1 V% G3 l% [
4 U$ w5 A1 E8 L;;;;;;;;;;;;;;;;;;;;;;3 l7 r' Y  A% b: \
;; Setup Procedures ;;
7 i6 y3 \) M9 _+ x) P, p3 d;;;;;;;;;;;;;;;;;;;;;;
' R! Z6 _, p$ W7 D/ t5 f+ A  Y" a: h3 J. p4 V+ z3 W0 R7 i
;; Initialize the display by giving the global and patch variables initial values.
# \7 L0 Q6 x, D2 g1 n5 i- ]# |;; Create num-cars of turtles if there are enough road patches for one turtle to
1 X* e/ q" G" m: f;; be created per road patch. Set up the plots.3 u1 E# k- C- s/ ?
to setup
, C8 g: a9 u0 o3 y0 `% h  ca5 p8 b- B9 |1 L3 C
  setup-globals
, c4 x  t0 C# Z$ G* }* j3 C6 c; z! T( `  F0 W0 V0 C, N9 t
  ;; First we ask the patches to draw themselves and set up a few variables
) d# ~; l: m) b$ C* Z  setup-patches) N+ s5 J6 t# K7 I+ d' ~$ t" ]! G
  make-current one-of intersections
- h8 d- }* M' Q. O  label-current
1 D1 m- J( P: p2 N0 g# J
  l0 G2 _: Y4 Z4 e. b. [  set-default-shape turtles "car"2 o7 }! b. q9 q0 Y$ P0 X( O

$ T* W2 U+ I0 Q  U$ o9 T* v  if (num-cars > count roads)7 G# R- [. @! f& O& b
  [6 [  l5 l# L7 ^
    user-message (word "There are too many cars for the amount of "
) W$ _1 e. f# ^4 d4 A+ r& f                       "road.  Either increase the amount of roads "1 S& m+ t  e# o$ K+ w- Y. ^% K! j' b# a
                       "by increasing the GRID-SIZE-X or ", X0 m( ?* k$ I+ M
                       "GRID-SIZE-Y sliders, or decrease the "
+ p- {" S& x( }                       "number of cars by lowering the NUMBER slider.\n"1 p% t& ~# N" c2 A; g  \
                       "The setup has stopped.")$ j) O  q8 r( R2 r; `) e
    stop: W8 Z- I: O3 S$ ?1 N- t
  ]/ Q. n1 l3 J+ f" M+ a

0 m+ c, O+ y* R$ ~  ;; Now create the turtles and have each created turtle call the functions setup-cars and set-car-color% Y3 l& H6 l" y( a) |) h: ~/ A
  crt num-cars
$ g9 s* m% W, H$ {1 t  [
# Q& `& i( P7 J& ~7 k    setup-cars
. o5 Q, H7 Z7 \- C: h! K. G* b$ c    set-car-color4 y: S9 v+ c5 @6 V$ ~, F6 _
    record-data
! R4 x7 d. Z+ ^& l; J( @  ]
4 @" [7 {* X% {, Z. K
! }% J/ w; l5 J; z9 m6 s6 ]7 B- b  ;; give the turtles an initial speed
% G8 w) F* \* G" K: V. V! F  ask turtles [ set-car-speed ]% c/ ?3 K8 B: t

& Y+ \. t" `0 S0 a3 }( o: @- a. g  reset-ticks/ v/ f9 t3 v( \; q5 F
end& S, u# a% m% ~9 A( q

0 b, j1 H  p* G; D1 o;; Initialize the global variables to appropriate values
- P9 F2 Q  B: U" G4 E  I' Lto setup-globals7 Q- ]4 m+ A; ?/ n2 H. ?8 O
  set current-light nobody ;; just for now, since there are no lights yet
+ M7 a1 _8 B! Q" B& T' Y" u  set phase 05 @) \7 v. a* ?/ Z- I
  set num-cars-stopped 0
0 W) ^  s* W* t1 W. @  set grid-x-inc world-width / grid-size-x+ M$ ^7 O- f7 g9 w2 ]
  set grid-y-inc world-height / grid-size-y8 J! d% h/ V8 B! e0 C6 O
  z. {( l  c" t" e; {) x
  ;; don't make acceleration 0.1 since we could get a rounding error and end up on a patch boundary
0 \7 B1 |: l2 M' W% _3 Q9 |  set acceleration 0.099
$ h+ J* T8 v: B8 |$ q+ Qend
! w: s; z2 W% q( p) |) M7 C# i# I, G* M! m5 K3 _# N1 w
;; Make the patches have appropriate colors, set up the roads and intersections agentsets,. n* V. P1 |" W& L+ y* m
;; and initialize the traffic lights to one setting
* X" n( i" \- y7 Q# E% xto setup-patches
4 Q  Z# q9 p0 x. D! s  ;; initialize the patch-owned variables and color the patches to a base-color
: n- g% J+ `9 b. S0 t9 k  ask patches
6 p, r$ p2 x# a: w  B  [: M0 D. r( _# S' j+ }
    set intersection? false
. `" U  C+ _8 a+ ]    set auto? false
2 ~- j. y2 L/ v; R2 F* h: ?1 X    set green-light-up? true
+ n' O7 G* d7 H" G! d8 K3 _) o& l    set my-row -1; k2 _, ]' e; x: J. a
    set my-column -1
; K( M- B& {5 E9 D1 v    set my-phase -1, j! Q- ], z4 @% M
    set pcolor brown + 3
+ f( O7 |/ A2 h) M5 ]8 w' Q  ]5 X- @, L: V, O" R  P$ P
+ E8 c7 [' A1 b3 e( K! Z- d
  ;; initialize the global variables that hold patch agentsets0 T7 x) ]3 K. Q+ N9 m' s$ W
  set roads patches with8 J/ ^% T1 w, P; R' M9 k
    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) or- K3 A  Q0 }3 m; x0 s" Y
    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]+ v$ @. ], C: f2 N: t
  set intersections roads with
+ K) z, {# H$ J+ l" e7 O. P    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) and
( f: C0 f) B8 }+ l& d    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]
/ d5 Y; `/ S* |
/ O) F) M8 V) h2 Y6 q% w0 ]  ask roads [ set pcolor white ]- j/ }8 U, J5 O! l8 x& b
    setup-intersections0 w7 k- K! v. [& F9 I* p" a
end
$ C* u- N, Z5 o9 d$ z; Z其中定义道路的句子,如下所示,是什么意思啊?* t% G+ y4 D$ ~" P$ R% G( x
set roads patches with( \4 ~5 E, z5 ~! r- G' j  I
    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) or
; ]2 g! }3 {( T- ^    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]; [, r8 v, l; c* 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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