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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& A8 q( N! M& _. X; ?2 U% A' Pnetlogo自带的social science--traffic grid这一例子当中,
5 d4 ?0 f- q% R; p! |globals
# q9 _) \8 g( t& Q# I[
( k) U9 W" P6 U# U6 [  grid-x-inc               ;; the amount of patches in between two roads in the x direction# y6 m, F+ P6 P) k" U, O/ w
  grid-y-inc               ;; the amount of patches in between two roads in the y direction
3 ?. S6 w9 ?  ~5 A) n  acceleration             ;; the constant that controls how much a car speeds up or slows down by if. k, O6 m8 P% G9 y
                           ;; it is to accelerate or decelerate
. j0 g1 Y+ v, g; K6 d/ F- H* f  phase                    ;; keeps track of the phase9 m6 ^( r0 P- `" b( T6 z
  num-cars-stopped         ;; the number of cars that are stopped during a single pass thru the go procedure( \1 v8 G0 S% q5 g/ O, U
  current-light            ;; the currently selected light4 Z7 g, A3 J+ {& A' e

# G$ h2 z/ r- L) `  ;; patch agentsets
4 v; S. l4 @* {6 }  w  intersections ;; agentset containing the patches that are intersections) W/ [! F8 d6 ~
  roads         ;; agentset containing the patches that are roads
/ }1 j3 M: O# T/ E3 u2 a7 y]
- Y( C4 S7 G  \; Q3 ~
& I' F6 H1 l5 }1 G& ?* o4 T% N8 `& Lturtles-own! Q- h6 Z% p% {0 ?
[: ^3 L0 v% b+ K1 @
  speed     ;; the speed of the turtle% N6 @( r! c) i- ~( p- n8 O
  up-car?   ;; true if the turtle moves downwards and false if it moves to the right
# Q& E+ y6 ^7 R9 d3 p  wait-time ;; the amount of time since the last time a turtle has moved$ Q+ B# c( k) O( m! E
]# W3 e. G+ x) l- b" |

; X7 x( D9 Y" ?patches-own+ ~& ?" R& f5 y: P  P4 o
[6 i2 b" k, n1 X' @8 Y) i9 Q% n% ?
  intersection?   ;; true if the patch is at the intersection of two roads
- v1 R* ?' {6 @& x6 U- K/ C& t  green-light-up? ;; true if the green light is above the intersection.  otherwise, false." t$ Q# |7 a0 l4 j' H) e
                  ;; false for a non-intersection patches.3 E+ a: R: W3 \+ r, a
  my-row          ;; the row of the intersection counting from the upper left corner of the
- d$ `4 I" I; V7 G! F/ D+ Y% v                  ;; world.  -1 for non-intersection patches.% r4 B9 i( A' f. ~- j7 c( j. i; Y
  my-column       ;; the column of the intersection counting from the upper left corner of the; v8 S1 a( ?. ^2 }1 d
                  ;; world.  -1 for non-intersection patches.
: O9 f2 F  Y6 \# V  my-phase        ;; the phase for the intersection.  -1 for non-intersection patches.& ^5 f( h% F+ z# s$ o9 V5 E
  auto?           ;; whether or not this intersection will switch automatically.
) I3 E. A, Z' C2 {$ ^9 u, N% A                  ;; false for non-intersection patches.: f& G6 D) Q9 j
]2 j1 z, F, Z+ A) t4 `! [4 e: e
; t) R# l7 X3 z8 p' Q' W5 X) |
9 J/ Z) b* n+ i' P% D  I! E
;;;;;;;;;;;;;;;;;;;;;;4 K8 o( ?! @4 y
;; Setup Procedures ;;% m4 \9 e  L  D0 R
;;;;;;;;;;;;;;;;;;;;;;7 W3 G; k3 i: V' `

2 P9 x9 g- [0 Q& Y' @% g9 z;; Initialize the display by giving the global and patch variables initial values.
0 N5 C2 ^2 x* l6 Z" X4 X( s4 [;; Create num-cars of turtles if there are enough road patches for one turtle to. D( H2 [* V" [6 V: I0 `0 g
;; be created per road patch. Set up the plots.
$ |3 ?( i- z% P5 P& t- E& bto setup
  j# ?( \4 X6 v. Y) H, S  ca" S5 {+ M4 e& Q5 P+ D* l# P
  setup-globals6 W. |8 O* g: ^6 R; L& B; u) x+ u
$ a8 h4 {" X* V7 C9 [/ u
  ;; First we ask the patches to draw themselves and set up a few variables
! Z/ y7 w, F$ M, b/ |  setup-patches
% a) K0 l2 ~+ [( j+ {6 s  make-current one-of intersections: H$ y! h* l% N2 T( v8 D
  label-current8 i8 M0 g- d; a7 h/ f

( c: s( n: t7 i" W6 O  @  set-default-shape turtles "car"
& x# h- J) M9 I- @9 w9 ?4 h. M6 Z8 F% H0 B( M
  if (num-cars > count roads)3 S1 f7 v. X. G; c$ E
  [
6 Y+ Z( E9 A7 x6 g0 J; @    user-message (word "There are too many cars for the amount of ". y7 W: g$ V& o% m+ Q
                       "road.  Either increase the amount of roads "
& z. }5 w0 H! z2 h4 R                       "by increasing the GRID-SIZE-X or "
( ]+ W& L- A* ]- g- d4 ^                       "GRID-SIZE-Y sliders, or decrease the ", q$ D3 Q- P# g1 e
                       "number of cars by lowering the NUMBER slider.\n"  T4 r* V$ N3 {$ e
                       "The setup has stopped.")
3 D! ^. ^8 G; a9 |8 ?/ \1 N    stop* g' E. K" l3 D2 i
  ]
6 V* [- f' [- L- E5 |
$ J$ J4 y& @3 ^6 P  ;; Now create the turtles and have each created turtle call the functions setup-cars and set-car-color
: S& Y, f, R9 B- n  crt num-cars# G3 F; l1 N  T$ |
  [
, ~# L& z& S9 y    setup-cars. x8 z; C; s- y  t1 p( w" G  h% o
    set-car-color
' Z$ d1 R3 P+ Q8 d/ l    record-data9 v& |& B" @8 A5 ~6 c% P
  ]
& i- T* D* [7 \$ w; Y' Q0 b: K4 o  l
  ;; give the turtles an initial speed+ \! q8 m9 l+ R8 |% {( ~
  ask turtles [ set-car-speed ]
& J3 V6 c" T6 n; b( Y
  P7 k  ^  s5 L1 e4 f6 A8 u7 R  reset-ticks
: p6 y! |% [4 fend/ C; L8 a! k3 Q: {+ [! G( ^1 }1 k

4 Y6 Q& p; ?$ t  Z; f;; Initialize the global variables to appropriate values1 p# o6 }) p7 S9 {  |+ N( k1 ^
to setup-globals3 M" t) I3 ?0 T5 v: t
  set current-light nobody ;; just for now, since there are no lights yet
1 a8 a8 a% `; V3 w* q  set phase 00 D+ Y* a% ^# T) x- `; Z4 |
  set num-cars-stopped 0
6 `8 }+ j& X! g  set grid-x-inc world-width / grid-size-x& D# g) m& `7 M: q& U+ [  g
  set grid-y-inc world-height / grid-size-y
; W" j# V  c& E. p
' y* E9 u" i2 k4 W" d  ;; don't make acceleration 0.1 since we could get a rounding error and end up on a patch boundary
4 l6 H% c5 q) Y6 r# R$ `1 Y  set acceleration 0.099( _4 e; W  H' s' S( U
end" N# W# l# S$ J  f$ n3 J( x

2 V  e/ ]1 l7 e" U' D" P;; Make the patches have appropriate colors, set up the roads and intersections agentsets,9 G0 p( u/ x0 j5 p
;; and initialize the traffic lights to one setting
+ I0 v9 K; @3 [! V+ J6 j: Nto setup-patches/ f& ^* o! a$ {8 _/ Y
  ;; initialize the patch-owned variables and color the patches to a base-color
6 \/ U( x! c7 ~# ]) p; r' j  ask patches. E- ~- B8 F- J6 o2 b- ?! l$ \/ P. X+ @1 H
  [
( w; `, P( o( w" c7 z    set intersection? false0 x( w4 E5 G6 U3 [" Z* C3 T
    set auto? false
# x0 _5 x+ L0 i" k- x5 e: L    set green-light-up? true
7 \  P2 {. A# A$ Z' e    set my-row -16 u$ M. s! I- N
    set my-column -1& [9 q1 h: c. L: i8 _/ [+ I
    set my-phase -1
. p! g" ]+ e( L! H  k: a    set pcolor brown + 3, d- q: _# M7 R5 y, K
  ]$ @. D8 d7 y5 F* G9 D7 z# y/ X
+ x# q- a' I* Z5 [) \
  ;; initialize the global variables that hold patch agentsets
* U. m9 h5 D; @  set roads patches with/ r) S( a$ p4 l  P
    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) or
2 R1 v1 j# G# ^  Y3 \* }- n    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]
4 g% d0 j+ m) f/ Z  set intersections roads with
7 ?+ U% z/ T# k: A    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) and+ i5 O7 O4 }) F/ P# w
    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]* T& b# ^# B* G, q% ^' S1 h3 F

5 K- N" i, z/ a3 o0 V  ask roads [ set pcolor white ]
# M' j; V: Q2 Z1 z+ h+ k% a    setup-intersections
6 \* e. S# t, `& Send6 [4 I' G: W4 _, k3 @. W
其中定义道路的句子,如下所示,是什么意思啊?
" N0 _6 P. w" d set roads patches with- }1 w  K2 v8 |! s, n0 v. D
    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) or' F4 y4 c% Y# e- Y8 [& l
    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]5 s! }0 H9 y/ e2 U7 C
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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