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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。% q$ K& a# r( z; o. {
netlogo自带的social science--traffic grid这一例子当中,
0 q, F8 f% S; ]3 Tglobals
2 G$ j6 k9 |, R0 g* D* s[
/ B6 _& y0 x6 L. a7 w  grid-x-inc               ;; the amount of patches in between two roads in the x direction: `! x/ j) K" x, o2 B
  grid-y-inc               ;; the amount of patches in between two roads in the y direction
# X* X5 y9 _0 Z* Q  acceleration             ;; the constant that controls how much a car speeds up or slows down by if
1 B( z- V* A* G, _+ r4 e                           ;; it is to accelerate or decelerate9 Y. c, q$ b- P
  phase                    ;; keeps track of the phase! i4 q4 E, _6 w
  num-cars-stopped         ;; the number of cars that are stopped during a single pass thru the go procedure
; m0 L; X& U6 l( c1 o, B7 R  S  current-light            ;; the currently selected light
' t/ ]2 x3 d2 }* p$ h" z4 h9 ~# k
  ;; patch agentsets
. l- E% _& N: J* z; x2 K$ R8 t4 t. ^  intersections ;; agentset containing the patches that are intersections. T' S1 J; k( k% n
  roads         ;; agentset containing the patches that are roads
. W, E# b, Q! e( \( o7 e% B]/ e% W9 _* L% G+ A' m

" y( Q; Y1 }" ^turtles-own6 d: x. t, n& n: o$ D
[
- k2 S: x. a  T' i3 Y+ V6 U  speed     ;; the speed of the turtle
) Z: V9 Q. c: k8 V/ B+ u$ M  up-car?   ;; true if the turtle moves downwards and false if it moves to the right
+ k+ L- s) e2 ^9 Y  wait-time ;; the amount of time since the last time a turtle has moved8 G) ~: @+ G) A( }) Q
]9 H2 ?# y" k1 s" o% r3 z  b

! Q" s* P, q6 vpatches-own
" N! G2 C6 w: I. K7 |[
: v9 q6 D+ G# [9 b3 [2 r  intersection?   ;; true if the patch is at the intersection of two roads- }2 G7 |! Y# B
  green-light-up? ;; true if the green light is above the intersection.  otherwise, false.
! M# i4 `6 p4 _7 m# ?3 i& O" V; z                  ;; false for a non-intersection patches.
; O8 |8 f/ C' i  my-row          ;; the row of the intersection counting from the upper left corner of the6 {5 E6 ~- h7 F) M, q
                  ;; world.  -1 for non-intersection patches.+ l- V/ T. t" T- _& [1 C! R8 k1 c
  my-column       ;; the column of the intersection counting from the upper left corner of the8 h: r0 W+ r, G1 o' T( ~
                  ;; world.  -1 for non-intersection patches.1 p$ @" \+ [& `1 e, e! i% k+ m
  my-phase        ;; the phase for the intersection.  -1 for non-intersection patches.
8 O0 [0 B" _7 \! b/ S6 c9 ]8 t  auto?           ;; whether or not this intersection will switch automatically.  |; E' m3 t0 c! Z- U: V
                  ;; false for non-intersection patches.% }# {) g1 }9 a+ Q+ S' a" ^
]. d) T8 S% o0 C" G
5 `% v, p* C, k+ K2 O$ D9 N6 c

: o; f/ r; \! {* e;;;;;;;;;;;;;;;;;;;;;;( t6 w! N: x: O: s
;; Setup Procedures ;;8 K. `% O1 j: b
;;;;;;;;;;;;;;;;;;;;;;
5 u( `) S: ?4 s! m8 M6 V* p' Q: U3 d) t3 w  z: J
;; Initialize the display by giving the global and patch variables initial values.
/ q& V* Z# f9 B0 D/ V; t$ w. o! I; k;; Create num-cars of turtles if there are enough road patches for one turtle to
, ], E& K* g/ ^( v6 f- _;; be created per road patch. Set up the plots.. g7 t* `9 Q9 }. C1 L/ l
to setup6 D! j' A! t' G1 v" u. ?5 y
  ca
. A+ m: z( ]( w; E/ l  setup-globals$ f1 ?2 S1 I) P& G8 @
5 j1 a" p" ^! u: J/ G9 ^
  ;; First we ask the patches to draw themselves and set up a few variables
6 y8 W. _* e4 `  setup-patches% W$ e7 @- y8 s* V" @8 J% X6 b
  make-current one-of intersections
, b6 [1 b: s8 h) T  label-current! r; A+ ~7 V5 E

$ c* x  h) X8 y+ N; r- Q+ J# N  set-default-shape turtles "car"
" a  f/ A; o9 H3 |% @8 l/ w3 C" W# w4 {
  if (num-cars > count roads)
8 S3 \. H9 A: r0 M. W  [* p* j. r' X) @- O5 h
    user-message (word "There are too many cars for the amount of "
8 v+ }/ P# M  _                       "road.  Either increase the amount of roads "
" \2 p* o# e; O0 ?                       "by increasing the GRID-SIZE-X or "- v: K7 n- Q" D9 J6 x, H& N' R, w
                       "GRID-SIZE-Y sliders, or decrease the "! p6 l  Q2 V0 U( G& }
                       "number of cars by lowering the NUMBER slider.\n"
. q9 ^1 X+ A  p" I3 W1 S                       "The setup has stopped.")
" d7 k# t9 Y; h$ D# ?0 _9 E! n& L    stop7 m* G) c/ Y! T3 n7 Q- ]
  ]
: k3 T" @* f1 g1 D9 s
4 A# u- A8 R8 `" A  ;; Now create the turtles and have each created turtle call the functions setup-cars and set-car-color
  Q  G+ t, ?/ V  W  crt num-cars& N& Q" L$ y, H5 v  y
  [
! ^) f& z  `6 D    setup-cars) m/ v2 n# c  V# m% ]
    set-car-color
6 T+ F  z$ F5 w$ p( I' l2 u. V    record-data
2 _. \- d" k9 f4 ^6 P* f! K  ]3 u8 I5 `3 q( Q( K7 [/ R; H
' D# Z/ A9 ]" A
  ;; give the turtles an initial speed/ g7 }0 ~. L7 n6 m/ p
  ask turtles [ set-car-speed ]4 u3 U1 `/ V+ P  a$ l% h* K9 b

: a" j+ S4 p) i7 s0 G  reset-ticks) v# a& K0 ]. H$ t) h; j
end1 Z0 I0 f$ f, T4 P# `. H
  q- C3 A% [: Q- Y2 s9 |
;; Initialize the global variables to appropriate values
" I5 d- F* ~8 X' m$ _% gto setup-globals
. o# }" {, V/ h) L6 _. ~  set current-light nobody ;; just for now, since there are no lights yet
% L( C% s4 Q. U3 G  set phase 0% S; |( ?7 R3 t/ l( H) {  Y) R
  set num-cars-stopped 0
" [/ A% J: c/ t- Q$ ^1 P  set grid-x-inc world-width / grid-size-x( {8 }+ I5 `4 q; m2 X2 e" P& Q
  set grid-y-inc world-height / grid-size-y
1 p" l/ ^3 Y3 Y' G/ N/ {5 S0 T" d; ~: }. }( |
  ;; don't make acceleration 0.1 since we could get a rounding error and end up on a patch boundary0 d( f6 B6 f/ I; }3 {
  set acceleration 0.0999 i# d: {) m$ ^+ t$ ~0 O4 R
end
) K- n9 }( A! o( x8 j1 @
; [) E* U% z5 R. T6 n1 \;; Make the patches have appropriate colors, set up the roads and intersections agentsets,
9 v+ h% {7 t' f;; and initialize the traffic lights to one setting2 a7 r3 W3 J( h: R/ m3 [: S
to setup-patches
0 J. Q8 W: E) ^* x- R2 o% w) W: l6 m! A  ;; initialize the patch-owned variables and color the patches to a base-color
5 x, `; m7 b7 v; F2 Q  ask patches
9 |% b6 w' C$ F! j9 [! g  [
, \- `, h* }+ K) A    set intersection? false
" \+ d0 \, f( |8 w3 G  \( U& @    set auto? false
) k# }3 x% A) l" H    set green-light-up? true
3 U( E! E1 u0 q6 _' L7 |    set my-row -1. y( j/ e- W+ s' I: K& E
    set my-column -1
% d3 U/ y* b9 j0 x1 F    set my-phase -1$ a* g, K, m& I5 ^
    set pcolor brown + 3( `8 w. M0 z3 k' w. l- D$ X
  ]% X. U- @) [+ C0 m# X* Y2 H  z
4 Y/ Z: d$ X4 _+ G8 a" q& g1 m
  ;; initialize the global variables that hold patch agentsets! g) @5 @( j% e
  set roads patches with
' n( M; a; l- {# U    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) or" i5 H" T* F. ~( q& A( T
    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]4 ?# B) q- @3 e5 R- m! P
  set intersections roads with: H5 Y/ ?. S& j7 A. R
    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) and; R  }0 E, a$ t
    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]2 ~; I  ?& H$ Q+ l

5 C+ ~7 b! M" }  ask roads [ set pcolor white ]0 h: T3 y6 V1 p* x
    setup-intersections
, O8 U+ \) P! t$ |end: O# W3 q" M- d7 o$ I8 D
其中定义道路的句子,如下所示,是什么意思啊?' e- q6 i, X* m/ y
set roads patches with
) f: s3 I% A$ T+ y: [3 T    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) or& _* i: x% D( i% {, O
    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]3 @; k$ p+ j2 [: Q
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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