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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 E  P7 c) T/ ]* x: ]. B5 a4 U8 K
netlogo自带的social science--traffic grid这一例子当中,0 m$ H3 T/ H6 F7 r0 }' U4 a
globals! ~7 w3 Y; C3 D6 o% D
[
  J3 w" M7 p# _" F6 ~  grid-x-inc               ;; the amount of patches in between two roads in the x direction4 w% ~# Y8 q2 ~0 y! t
  grid-y-inc               ;; the amount of patches in between two roads in the y direction
9 u* M& _5 [0 q+ J9 s  acceleration             ;; the constant that controls how much a car speeds up or slows down by if
' u2 L) _  o/ {. ]                           ;; it is to accelerate or decelerate+ b7 T* [7 m8 B
  phase                    ;; keeps track of the phase$ n, V9 [$ t! }' J  u. x8 u
  num-cars-stopped         ;; the number of cars that are stopped during a single pass thru the go procedure
2 L, k! C/ k" R  current-light            ;; the currently selected light0 R! \, K1 l+ x8 t3 E' I+ _
2 E! d) |+ i2 P! w4 S: q* k
  ;; patch agentsets
7 R; k9 e6 _- b5 ^: L  intersections ;; agentset containing the patches that are intersections
2 M+ U2 L* a7 l3 k  roads         ;; agentset containing the patches that are roads1 R& ], q5 j3 J- F4 G6 L
]# p0 U( d% x+ o8 I
8 s8 t, N8 r# ?5 S. v1 R3 d6 t; C
turtles-own: \; b: @1 o8 a/ r$ ^
[
/ A- c; t# N$ N1 ~  speed     ;; the speed of the turtle
% a/ Y: p5 u7 p% ~& _( h. a  up-car?   ;; true if the turtle moves downwards and false if it moves to the right
2 @4 x: J( i3 H9 N$ b  wait-time ;; the amount of time since the last time a turtle has moved, x, Z6 Y" l) a
]
/ A9 W) p$ n6 r9 a( P
: @# Y' Z$ ~, L4 y$ }+ h/ t' H* Hpatches-own
  c" s, L$ p5 v9 H, n[- g: u; I  u% s: Q( ^( F
  intersection?   ;; true if the patch is at the intersection of two roads( f( T2 g# B2 n3 u- z
  green-light-up? ;; true if the green light is above the intersection.  otherwise, false.3 ]! U2 Q7 ?' M+ q7 u
                  ;; false for a non-intersection patches.
, f% U' L6 u" ?* `+ ^  my-row          ;; the row of the intersection counting from the upper left corner of the
: [& v9 _+ j: f! ~3 }6 z, }( P                  ;; world.  -1 for non-intersection patches.- f. i4 G& w" A
  my-column       ;; the column of the intersection counting from the upper left corner of the
6 {, j: R$ e  ?4 }5 G                  ;; world.  -1 for non-intersection patches.8 d- @7 c5 |4 q$ i( M: M- K& L) C
  my-phase        ;; the phase for the intersection.  -1 for non-intersection patches.
) f( T) {+ m# I$ E4 Q% k  auto?           ;; whether or not this intersection will switch automatically.
& V. G1 P0 Q3 \, a                  ;; false for non-intersection patches.
5 T, b4 k: Y8 _/ z& ?( R, H]
3 H4 Q7 _  d/ q: M8 Q; t  ^' w0 g; }) h  f$ g8 G. m' q' D

( r3 \! l, y  J3 b: D- m0 S;;;;;;;;;;;;;;;;;;;;;;
; L7 D6 f# G- X  Y% b& ?;; Setup Procedures ;;$ [  c7 N/ x7 q* M. b3 ^3 G4 h/ q
;;;;;;;;;;;;;;;;;;;;;;! O( @6 M3 r' d

, Q& p& X+ q  R, S; j6 z;; Initialize the display by giving the global and patch variables initial values.
# M' L5 |3 `' Y4 u$ ?;; Create num-cars of turtles if there are enough road patches for one turtle to  G. n1 a5 Z+ E/ }0 [8 c5 {% x
;; be created per road patch. Set up the plots.
0 v3 B7 u, G& q  `to setup
; z; Q& L' i7 s, V0 N  ca
7 Y' k' u; F, o  setup-globals0 N% F: {2 D: ?0 k! t* _8 A

: [& B- Y# |: I6 z  ;; First we ask the patches to draw themselves and set up a few variables
2 N2 j4 S7 z) L; [9 O  setup-patches
( P: Z, l$ i- `6 Y( g3 z  make-current one-of intersections
; S9 r4 R; c$ o; O( F; h! T7 i( X  label-current
5 t0 S; C; t2 l4 d
2 |. ?4 G2 b* G* l* P7 K  set-default-shape turtles "car"1 U4 B( O7 }, o; d
1 E/ g: F1 I0 ~0 C
  if (num-cars > count roads)
4 G* Q4 c2 a0 t' H# R  [3 Q% s: s' q! G' |
    user-message (word "There are too many cars for the amount of "3 M' u' ]2 N4 o
                       "road.  Either increase the amount of roads "3 A' D: v% C) j! s  J" s1 L1 b
                       "by increasing the GRID-SIZE-X or "' x+ H6 C2 Z8 t& C6 x! P3 F
                       "GRID-SIZE-Y sliders, or decrease the "' O  S* j+ X+ W) M2 P
                       "number of cars by lowering the NUMBER slider.\n"
6 d1 S( Z2 x6 L8 I& u                       "The setup has stopped.")
6 F3 G+ b2 Y* F8 ]% \" M* Y    stop5 j3 y8 v  B7 Q$ \: O) F7 P% b
  ]
8 m: Q5 [. q7 F0 N6 }) c3 q, W0 X* v& K) h' w. f
  ;; Now create the turtles and have each created turtle call the functions setup-cars and set-car-color2 @% `3 w! e& d! m! z8 H
  crt num-cars
/ `- B" F' q5 [: x: M6 I2 K  u  [
! O0 [' R: C8 W" S4 B+ g2 x    setup-cars
( }( X! r7 b1 v" M    set-car-color
( J5 E! N% n1 i$ l5 f    record-data
1 k# J1 R0 ]/ Z8 }( k  ]
, n' V: }+ \7 j6 o
. O+ n8 r" h  a  ;; give the turtles an initial speed+ d7 @& p  S6 b' K6 u; c; E
  ask turtles [ set-car-speed ]
9 L7 d1 a* E. D7 m( p7 U7 G
' h! N: `) X: s% Q4 V* J  reset-ticks4 E2 n3 `& @% I( f5 P
end# v3 e7 O/ r7 W# u$ Y& C/ d& s
- ~* [. ^" _' n2 h, f
;; Initialize the global variables to appropriate values' _9 D' j- a5 W: h. T" C
to setup-globals
; t8 a6 e0 R1 @8 l3 I$ X: v  set current-light nobody ;; just for now, since there are no lights yet
8 \+ y2 ~* P! P  O  set phase 05 j6 Z) q! r* X  W  f! w( z
  set num-cars-stopped 0! t* U% T* E. f/ {, U
  set grid-x-inc world-width / grid-size-x4 L+ M7 o6 J1 J8 ~1 J4 e
  set grid-y-inc world-height / grid-size-y
1 S( W' C7 A- Q1 a3 s; M, b
# O) y/ T- c6 q3 {3 U' f  ;; don't make acceleration 0.1 since we could get a rounding error and end up on a patch boundary6 `% F8 T6 M& D6 e1 U' }
  set acceleration 0.099
6 d" \' s' i4 u- C* nend, E' H+ B/ m+ ]+ p. E# a2 {+ }/ a; m

/ v" B( M( h" y- g& c7 ]+ _7 k;; Make the patches have appropriate colors, set up the roads and intersections agentsets,' c& I) e  v; g( A5 X5 a
;; and initialize the traffic lights to one setting
2 j- {9 ]# K4 C# p" ^0 Vto setup-patches
' T1 w" h  l2 E. O/ g9 s  ;; initialize the patch-owned variables and color the patches to a base-color. ]- C. ?, t0 E: F# ]- c* q
  ask patches8 U  M/ F9 a% X% o# G8 V
  [
( ?7 ~7 f# u8 `$ Y/ e& l! N7 Z    set intersection? false
. n3 b+ Q/ ]) \; t, N- h    set auto? false) ]) S1 m0 E+ X" l) U+ `
    set green-light-up? true6 |6 x, n- l9 W1 W
    set my-row -1
% O% C  ^7 H7 n3 n$ n7 A8 A    set my-column -17 z* V" D# k2 _4 `" ~( J
    set my-phase -1; _% _7 `- Q* x8 K
    set pcolor brown + 3* R) B# ^) D" Y$ o2 g& D
  ]% I& X2 e9 [4 I' Y/ }  @  E& I0 ?

+ X( w% N$ s* n: L/ k1 n" M  ;; initialize the global variables that hold patch agentsets9 k( u( m, j# M/ N
  set roads patches with7 o& N. f7 A: c$ _! |0 g. Q
    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) or
6 H( P: D- F; V" ^# ~. r    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]
) [/ g7 m8 W: o& K* R  set intersections roads with; Z( [4 j6 w! q7 h
    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) and
/ @* o' F7 `: m4 E8 v# c    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]. q; c1 Y; ?9 U$ {6 b6 z" j
% t2 i  t8 x* _5 G7 [  N. k1 f
  ask roads [ set pcolor white ]
  o3 h& `# q0 S" W- k+ ~! n" J    setup-intersections5 h( d/ O: N3 y) f1 t
end
* s5 w* V- V8 G9 X其中定义道路的句子,如下所示,是什么意思啊?
/ \( V+ V6 K7 v+ f- P( W) [ set roads patches with+ B9 ^- w% W) s3 q8 F
    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) or
/ {1 u, v& }. O4 d3 m3 u* K- F9 D    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]
6 v4 w9 _% [- C5 D/ W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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