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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。
+ b$ A* R( V8 M& f" X' c/ b- enetlogo自带的social science--traffic grid这一例子当中,
- u& \) V6 M7 c6 ^globals# W+ M( Q* `9 Q  a8 M" q5 c/ D" {
[
8 M0 A& E, d/ ^' V8 k/ g  grid-x-inc               ;; the amount of patches in between two roads in the x direction
3 |" B8 |. }4 L! W$ ~# N8 H  grid-y-inc               ;; the amount of patches in between two roads in the y direction( I+ Q8 Y3 U6 l5 I9 a
  acceleration             ;; the constant that controls how much a car speeds up or slows down by if4 c7 m! i: |- ]
                           ;; it is to accelerate or decelerate
( b# }2 Y: D' b& _) [/ J1 L' Q; r  phase                    ;; keeps track of the phase. f3 ^) `8 t+ ^( P+ \8 f, E) k3 X" {
  num-cars-stopped         ;; the number of cars that are stopped during a single pass thru the go procedure/ M2 v: u6 U" P+ k5 o
  current-light            ;; the currently selected light% S! ^/ W+ W% o. ]
, s& |3 _5 S0 s% m" G; e
  ;; patch agentsets
9 v1 D( z3 Z5 @: Q' Z1 X8 |  intersections ;; agentset containing the patches that are intersections
' D5 Y6 t6 K1 g) U! ~  roads         ;; agentset containing the patches that are roads) f. F7 ]! k: |$ T; r
]
6 _; T0 g/ ]$ x" n2 g' |6 Z
  B7 e+ e/ m! J" h, e0 wturtles-own' r# v: T2 @. j* }& X- l. n4 x
[+ ]; I0 K+ y: @- c4 y' r2 \! l- w
  speed     ;; the speed of the turtle$ p$ a' \4 E, ^* s  Q. j
  up-car?   ;; true if the turtle moves downwards and false if it moves to the right7 S, G1 F4 F6 D! P! \4 H
  wait-time ;; the amount of time since the last time a turtle has moved* R( M9 O! }7 q
]
: a1 E; `1 p0 b, w: B2 t9 x. |1 j" R7 [; V
patches-own/ K1 r5 Z3 T4 B+ f3 V; D
[& G5 w* B3 {  F. O# y2 @( r
  intersection?   ;; true if the patch is at the intersection of two roads2 X4 d7 j2 g' q3 n
  green-light-up? ;; true if the green light is above the intersection.  otherwise, false.( L0 B& G9 ~% Q  O% e: o3 N
                  ;; false for a non-intersection patches.1 Z  M3 P8 N$ J
  my-row          ;; the row of the intersection counting from the upper left corner of the0 j  Z6 G' n- t
                  ;; world.  -1 for non-intersection patches.
3 w6 X; e" }+ M$ N  my-column       ;; the column of the intersection counting from the upper left corner of the1 P" ~. C' u6 B4 A6 V  x; C
                  ;; world.  -1 for non-intersection patches.
' ~* S0 a8 q! A& b, `! K  my-phase        ;; the phase for the intersection.  -1 for non-intersection patches.
5 g# C. `; m" y; r  auto?           ;; whether or not this intersection will switch automatically.
. T6 p6 m2 P3 \& J' A                  ;; false for non-intersection patches.3 l6 w/ P( T- t- V
]
' @% u8 z$ L) [9 ^
4 ^, g4 A( Y, W2 |
* {1 b: D2 X6 b;;;;;;;;;;;;;;;;;;;;;;
3 N7 n, C% p& G& C' m;; Setup Procedures ;;( g/ n1 D0 x, R: e5 A$ X
;;;;;;;;;;;;;;;;;;;;;;
4 R+ P% l( ~7 D4 g6 i" o
. l$ K9 g& U+ a8 ]+ g;; Initialize the display by giving the global and patch variables initial values.
/ @! X2 b: M1 J2 g. P;; Create num-cars of turtles if there are enough road patches for one turtle to$ E" u5 E6 i6 a% Q# H, f& ]/ v
;; be created per road patch. Set up the plots.
3 `" w  a9 R$ fto setup! A7 `( |1 k/ F$ k% b# ]. S
  ca, ?' c; a$ n0 ?8 w: b
  setup-globals
1 {1 n. x' {% D+ X8 i
) Q- b) d5 C! w  ;; First we ask the patches to draw themselves and set up a few variables$ l3 I) B; Q+ R
  setup-patches
% s7 m. l  ^1 T  make-current one-of intersections! ^/ u& m7 ~: n. b
  label-current0 h" f+ l; @3 \

" X! d8 ?, f* r+ L0 Y  k$ ]  set-default-shape turtles "car"
* C$ ?; H( p9 U+ S
/ t) ]+ J8 |) O( V: H  if (num-cars > count roads)
1 m- j( n( ]. n, W  [
5 s8 G: R  V6 f" P$ N    user-message (word "There are too many cars for the amount of "
5 M  Y, R' y  I( m                       "road.  Either increase the amount of roads "
" V8 F1 U' d/ e* a) m" e. Y' w/ w                       "by increasing the GRID-SIZE-X or "9 k% g4 S$ d4 R7 f8 K
                       "GRID-SIZE-Y sliders, or decrease the "
" O- t  B. G* S0 z) }4 M( V3 P) A. m                       "number of cars by lowering the NUMBER slider.\n"
/ ]$ @% j' x) Y; F; Y' R                       "The setup has stopped.")
' `; s6 e" N) Z" i    stop) W! m8 U9 D9 K, I7 O' v
  ]% k6 x/ V( U8 r# ?% J2 M5 B2 @0 u
' Q3 J9 J. N- b0 R: H$ Y
  ;; Now create the turtles and have each created turtle call the functions setup-cars and set-car-color
: o% C% B# G1 G" ^1 D: y  n  crt num-cars# U) {* ^; E' ?3 T, [( `# G
  [: p; S& N' ~! g3 f3 X( r
    setup-cars7 z2 h, h( ?% A) Z1 Y
    set-car-color) `& s5 \- ^9 S7 K% i
    record-data
% Z6 S# W% G" p3 m  ]8 Y! B' K! z( Z# c; w6 F' O

4 L$ D6 A7 R6 Q6 l$ u  ;; give the turtles an initial speed
& ]$ L- K' M4 }$ e  ask turtles [ set-car-speed ]
  E; ]2 L$ O0 v/ s& K# d- k0 r  ?
: _) t1 P4 k2 V6 \  D# n& |. ~( D  reset-ticks
) B% E: y/ R3 {2 m( gend4 F# @( i5 i4 q) O$ L
; ], b! M# I, c
;; Initialize the global variables to appropriate values( ^3 V: M. B7 N8 ?- a# V; T
to setup-globals9 k; f& }5 E" C
  set current-light nobody ;; just for now, since there are no lights yet
9 _9 `8 X, K9 b& M  set phase 0# P( C+ b' j0 a& f6 P6 U6 L; r
  set num-cars-stopped 0; v2 }2 y9 o' R; j
  set grid-x-inc world-width / grid-size-x) X0 o$ m  n! [% _' x7 t
  set grid-y-inc world-height / grid-size-y
" W  i+ }- y# |! N2 F& M/ A( `, r! d. f3 l6 T4 T: j! N
  ;; don't make acceleration 0.1 since we could get a rounding error and end up on a patch boundary
' p* ^3 S+ C% y  set acceleration 0.0998 Q3 Z) W9 C3 a$ U8 C! y3 D
end+ t: H: H! e% u$ j1 A
- S) s/ f/ L  @* i' R# \
;; Make the patches have appropriate colors, set up the roads and intersections agentsets,+ l8 H. U4 t! V& \
;; and initialize the traffic lights to one setting
% M2 K' E* @& q1 Z& Oto setup-patches$ V, a5 e5 V2 J/ [) Y0 j
  ;; initialize the patch-owned variables and color the patches to a base-color
! a9 U& }( e7 c6 `  ask patches5 c# Y, |; l4 L8 |6 c
  [7 R$ h& g* D7 k( n) l* l
    set intersection? false8 U' H* A8 w8 Q* M, J
    set auto? false
: D) p% O/ I$ t* I* @2 G, Q    set green-light-up? true0 G  Q7 C; {# F; X7 C3 h/ V5 i
    set my-row -1
6 P* y% v# k3 b) x( s  e, q    set my-column -1
5 @2 I$ e: y" k9 \: k5 N3 S    set my-phase -1
( c# b- u. v7 |" K! ?0 k1 n( e    set pcolor brown + 3
* L5 e% }4 i4 G3 q  s8 w  ]$ T2 f; R0 D/ A4 |. Q

5 Q' F7 k) N* o1 D3 J9 r  ;; initialize the global variables that hold patch agentsets
+ z7 h& G# W, t4 U: z' }6 n  set roads patches with
3 P3 T3 i+ U% J+ x9 z2 g. E    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) or
" I( j2 C8 i6 L. D1 [4 e    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]
4 J% {, `: g; U- V  set intersections roads with
. }( E4 X! V, |3 J9 G+ U& q5 I    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) and
* }) |8 d+ a3 H1 N5 K/ L2 I    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]
1 x6 M1 k% m5 B, u
; ~/ H6 F9 q) a' C2 J; j  ask roads [ set pcolor white ]$ t8 l1 z5 K8 m! P5 ]1 f
    setup-intersections
6 C, H# T1 p! G, w: i, k! B3 aend
8 o0 }+ W; u% K4 T# H8 Q8 h7 N其中定义道路的句子,如下所示,是什么意思啊?3 D  X" I( E( M% S5 y) {
set roads patches with
0 ^+ R& ]% l& c    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) or3 X5 {2 z! f3 C, _
    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]4 _( Z5 O& T* @. N
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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