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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。; ]% @9 @6 v  d7 p: K
netlogo自带的social science--traffic grid这一例子当中,, j* V! q! J) b
globals5 d( `4 C5 d7 O- j0 d) I7 |3 E* x; m
[
7 b! `8 f, h4 W  grid-x-inc               ;; the amount of patches in between two roads in the x direction
% M2 M$ U: v* E7 O+ Y9 X' ?; g2 b+ m  grid-y-inc               ;; the amount of patches in between two roads in the y direction
2 _. U' S: o( N  acceleration             ;; the constant that controls how much a car speeds up or slows down by if
' \5 U* z% ^4 \8 ?3 C                           ;; it is to accelerate or decelerate* D/ H5 U/ w; f0 a8 c
  phase                    ;; keeps track of the phase1 x0 ^3 n7 z! W
  num-cars-stopped         ;; the number of cars that are stopped during a single pass thru the go procedure
+ `" I2 L& z4 h4 \7 {0 \7 W- U! v  current-light            ;; the currently selected light5 z. l/ ~7 |6 ~. K: _9 m
3 |* d8 T0 i$ G
  ;; patch agentsets
$ S) t4 g1 V0 L  intersections ;; agentset containing the patches that are intersections
4 o: \5 {% [1 y  roads         ;; agentset containing the patches that are roads
& S" I5 i) b3 u0 m]
! M: y; r7 F3 H# d; X$ P* r7 X# F# O/ ]+ t* @+ P, z5 `
turtles-own" n! \& r6 b" ^
[0 l, i$ y* Z1 Q$ @* s" F. f
  speed     ;; the speed of the turtle7 G8 U0 o% R* I5 ^
  up-car?   ;; true if the turtle moves downwards and false if it moves to the right
5 F3 a1 t$ d2 @, _  wait-time ;; the amount of time since the last time a turtle has moved( S' X6 r9 b0 D% f6 ^" v
]
  u0 ~; r, v6 R6 ^! O  V( I1 e+ }' W7 y/ v
patches-own
7 F. k, q3 Z6 N[
& N0 H- v- t2 G) t7 B2 n8 t. q  intersection?   ;; true if the patch is at the intersection of two roads) s* \* \" C: ]( T& U
  green-light-up? ;; true if the green light is above the intersection.  otherwise, false.
, L/ V* B+ }' r5 |) W                  ;; false for a non-intersection patches.
8 Q8 Y- |6 S+ b2 _8 N& ~  my-row          ;; the row of the intersection counting from the upper left corner of the. t1 l% ~/ A( |. A/ J( a6 ^$ q
                  ;; world.  -1 for non-intersection patches.
# G3 j' n: E& r% @% I! L* @8 m0 }0 a  my-column       ;; the column of the intersection counting from the upper left corner of the! t" Q# ^: A* d6 x/ K& H& l9 e  d( f" E# @
                  ;; world.  -1 for non-intersection patches.$ F, ^; m" v9 E1 e7 I  W2 w
  my-phase        ;; the phase for the intersection.  -1 for non-intersection patches.
" ?$ |4 m$ D  d  b" @" k0 X  auto?           ;; whether or not this intersection will switch automatically.
* b! g3 l$ {: l! w2 @                  ;; false for non-intersection patches.% n3 m1 I/ F  ^' B0 s9 O1 K% Y
]) M/ \( v4 ?" G8 Z3 |' `" E

5 q( e# l, V% F0 T( H, f0 ?3 f5 y
! b' s! U9 }: f0 X- V' X7 w, d0 p;;;;;;;;;;;;;;;;;;;;;;, G- s: I0 t: O- ^7 c7 M
;; Setup Procedures ;;
8 ^! D  |3 d2 L$ G( m2 T/ O' g;;;;;;;;;;;;;;;;;;;;;;
' w  z2 o6 ?' ]/ w6 O- p! M+ _/ e
;; Initialize the display by giving the global and patch variables initial values.
; W9 h/ [$ L7 W3 f0 F;; Create num-cars of turtles if there are enough road patches for one turtle to
' e9 }4 z/ h1 u; @;; be created per road patch. Set up the plots./ _' M+ K& g0 s8 F9 A6 z
to setup
2 R% e- |  N3 Q5 T* s  ca
9 r# ]+ T6 l# J% g3 {6 {7 f; R" }7 U  setup-globals
& B' h5 e; q. g0 N- o: G, ^, e* w. h! p0 |3 o! v
  ;; First we ask the patches to draw themselves and set up a few variables2 a) f" y" w" P  D& X
  setup-patches* D( G3 k; y, ]7 d* U; Z0 _* n
  make-current one-of intersections7 y, L2 B3 N& ]  _6 @8 P
  label-current5 J5 [1 Y$ K8 V
) J, N; o5 c) L, t5 Q
  set-default-shape turtles "car"9 o$ q2 g5 U+ r- \' Z

9 r" ~/ n% o. |' i  r4 z2 A' m- K  if (num-cars > count roads)
' D! q2 k8 Z/ l" ~- w# n  [
  I/ _6 a# U( M' m    user-message (word "There are too many cars for the amount of "2 |! D5 V. `) U- j, J
                       "road.  Either increase the amount of roads "
& t$ a- e3 d. }1 v                       "by increasing the GRID-SIZE-X or "
6 c, N: N- `7 B                       "GRID-SIZE-Y sliders, or decrease the "
) w. K9 F7 r! o9 n                       "number of cars by lowering the NUMBER slider.\n". u$ p2 y1 y  e3 D% W! h. u
                       "The setup has stopped.")7 y5 U5 S- Z/ u% q& h9 t
    stop
& ]( W# u. ^2 ~# W& y1 E( G( x% [( E1 z- p  ]
: _/ l! |# }' T: W( X% C! [' t/ g0 }. p! f
  ;; Now create the turtles and have each created turtle call the functions setup-cars and set-car-color9 ~0 T4 ?2 p4 M3 j# }4 i
  crt num-cars" b, J6 b9 l2 i& J& p: f
  [2 O3 C% U4 g7 P
    setup-cars
% d" }) [% T  b" I8 ]    set-car-color
& a/ L4 p: q+ I+ o" B; b    record-data$ m$ {; x6 v# V3 D5 p/ a/ |
  ]& K! W5 o6 X: D

, G2 S/ Z, y, q' L8 B7 r  ;; give the turtles an initial speed% D5 ~+ v6 |8 }
  ask turtles [ set-car-speed ]
; `# t' [% J, k' M4 G3 D' K' d" e1 v/ j3 E3 L% h+ F! E
  reset-ticks
& A- Z% J3 s1 V1 @1 iend! A9 v9 L' q0 Y! e6 m5 s
3 r, I9 R* ~! s) P- V* e
;; Initialize the global variables to appropriate values
) o* @- f, Q! u' k: Dto setup-globals' I9 M2 M. F2 O" I1 A2 c+ S6 t9 e
  set current-light nobody ;; just for now, since there are no lights yet
& X1 I$ Z' \2 V& z9 \8 u  set phase 09 F" I- |6 [0 ^8 S+ q& ]. r
  set num-cars-stopped 0& q4 _! _) G9 N) S" w
  set grid-x-inc world-width / grid-size-x- j) }* O* w' d) X" ?" {: Y9 [+ F
  set grid-y-inc world-height / grid-size-y- l5 o# K$ j' I! ?* u7 `
4 z8 Q& l+ ?, M. e, E
  ;; don't make acceleration 0.1 since we could get a rounding error and end up on a patch boundary( b- X- t3 }0 `( z3 Q( M/ c
  set acceleration 0.0994 ^# U3 B, U2 \( C* N; W
end
  t% s8 O. m7 c2 c4 }  r2 I5 }; D0 L8 w  e
;; Make the patches have appropriate colors, set up the roads and intersections agentsets,
* W- ^4 Q; ^0 y9 ]* |3 _. w) \;; and initialize the traffic lights to one setting' B1 e% J% }8 o
to setup-patches
! K' M" n* ^; j8 S  ;; initialize the patch-owned variables and color the patches to a base-color5 m4 |7 Z1 R/ o7 M! E
  ask patches
$ o6 I. f/ {" Z2 {  [
3 _1 R2 m/ i# X6 R) j    set intersection? false
" J; }: }+ U  h4 j: O/ \! M3 v5 ~    set auto? false
, U. v# C& M, E( U- _! ?! C% _( K+ G% i  \    set green-light-up? true
& G1 Z* `( G1 o! H0 Y    set my-row -1  k9 X8 F8 t- j: H. m  g+ D+ e1 C
    set my-column -1; r! Q/ V, h3 ^# c* ^7 q  _
    set my-phase -1
# ^; h+ Q$ n* P. g    set pcolor brown + 35 H" |6 E3 Z4 u  [: t+ |
  ]! u: R/ W0 T2 A4 [0 U; p
" O" z/ r( s* Z6 U% n: ]
  ;; initialize the global variables that hold patch agentsets) Y  v0 V( d" D4 R% k* E2 N# E
  set roads patches with# l2 S: d  U3 v7 O  r* R
    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) or, P. p+ @' b' m3 U  S
    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]9 U' Z7 m+ d$ v0 P0 X* z* ]* ]
  set intersections roads with
9 t, }, _; d4 l. Z8 J9 l) q) T" R    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) and
( Y, s& K& W# s- P. o6 v    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]
3 W2 E- a. o  E8 q, ^( ^
9 u; X7 E. s8 V& @9 f) |  K' q  ask roads [ set pcolor white ]
# r, V/ Z( b$ m7 H3 `2 D% A9 u    setup-intersections
% P/ E, c  m2 I* K/ W$ U0 [end/ ^) Z% V+ ?) U
其中定义道路的句子,如下所示,是什么意思啊?
) t# n0 n/ H& ?9 Y8 _/ [% k1 ?; k set roads patches with" E% r# [3 b; s7 o
    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) or
- {9 }  V: Q1 c- j/ D    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]' y# y0 D- ^; V# L' l" |
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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