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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。# e9 Q- n5 L" \/ R) J
netlogo自带的social science--traffic grid这一例子当中,0 g; Q( c: q+ `* u% U
globals
% k4 l2 h; _: w; N" J4 P1 I[+ J8 n. g% N8 B: F
  grid-x-inc               ;; the amount of patches in between two roads in the x direction
) @6 j/ i, `4 k0 A  grid-y-inc               ;; the amount of patches in between two roads in the y direction! [. f0 |: v. p; R* [0 d, x" U
  acceleration             ;; the constant that controls how much a car speeds up or slows down by if7 X  Y, m, M5 T3 X
                           ;; it is to accelerate or decelerate: q, J9 b( L. ?* G3 M" v
  phase                    ;; keeps track of the phase) h. K, k6 o& W- s& R2 b
  num-cars-stopped         ;; the number of cars that are stopped during a single pass thru the go procedure
" J& K: K* B4 U3 }  current-light            ;; the currently selected light9 m0 p; o5 x5 o/ m/ Q

% R& S8 S0 I5 r, ~. a! u# w! k  ;; patch agentsets
: ~2 W$ }( `( c" Q  intersections ;; agentset containing the patches that are intersections
5 z+ ~' M- W: Z9 g  roads         ;; agentset containing the patches that are roads
  `1 M5 z" q) p8 O& e. R8 d0 ^]( p' {$ u  J5 K4 q

" }. d- _; {6 s0 |2 Zturtles-own
4 w" ]# r. c, X5 B, u; g[. E" e. |: F( W% ]+ k
  speed     ;; the speed of the turtle7 X$ q* l' h( H# q* k8 o( f
  up-car?   ;; true if the turtle moves downwards and false if it moves to the right5 n& N) k0 P5 @7 P
  wait-time ;; the amount of time since the last time a turtle has moved) J* N2 ~2 ?! S5 o( w$ A) K
]
* d6 @: J; a* C( [: u# q: D4 F+ E: S" ]" W
patches-own
4 g0 O7 O. \. `; Y' ^[# ?# i4 T& ]" w
  intersection?   ;; true if the patch is at the intersection of two roads9 h$ I  E$ E& \2 [9 t
  green-light-up? ;; true if the green light is above the intersection.  otherwise, false.# P0 A) {4 V9 @4 Y
                  ;; false for a non-intersection patches.# L& ^! j/ b2 e" a+ l$ ]+ I5 R
  my-row          ;; the row of the intersection counting from the upper left corner of the
( B% q: ~0 s) [2 @# f& }2 j; |5 k( f; T' m                  ;; world.  -1 for non-intersection patches./ ?, V- ^6 q, z) H1 T
  my-column       ;; the column of the intersection counting from the upper left corner of the$ ~4 g' e* H, `% Z6 _0 P. r
                  ;; world.  -1 for non-intersection patches.
2 n! e" |" q' i( E. `" B) k  my-phase        ;; the phase for the intersection.  -1 for non-intersection patches.9 d! @& v; \& @- s; l5 O/ U
  auto?           ;; whether or not this intersection will switch automatically.
) L! M: x/ r8 z& u5 [% U                  ;; false for non-intersection patches.
/ N8 Q. Y+ H3 k  U# |. {8 C]2 @* u2 _8 J* B7 P6 E
; K1 V, a% q& `' R+ ]: A- C- N
; J  o; x4 ~% P! V; l
;;;;;;;;;;;;;;;;;;;;;;
" U9 h' z/ O3 l, {. a. `0 Q3 D;; Setup Procedures ;;! B0 L" U7 k+ L) [4 Q! z9 G
;;;;;;;;;;;;;;;;;;;;;;
6 w! I7 ^) b) x$ S
7 E* X& J/ o& R7 R3 ^; `* l;; Initialize the display by giving the global and patch variables initial values.* ]( U9 _, X  ~' b( z
;; Create num-cars of turtles if there are enough road patches for one turtle to' [& f  W6 }" {* P
;; be created per road patch. Set up the plots.
; o9 A* Z! }; yto setup
) M& Y$ c9 P  f% o6 `  ca
4 H  P% S7 _0 D, M  setup-globals
9 M; h: g5 F% d3 b0 N( {( H
4 z8 t  M$ L* {8 t; ?$ V" @  ;; First we ask the patches to draw themselves and set up a few variables
' D2 H( e9 @% }- d! {% ^: |  setup-patches
5 X$ ^# ?  x4 H1 A  make-current one-of intersections
% l  b1 l  k/ T* ~+ ^  label-current
' S, R$ p6 L" I- l& a; L- o6 P, [
' s" W5 d+ Q/ ]: K  set-default-shape turtles "car"5 v- i- w1 J5 d+ }# R( `

" p8 X3 U/ Z7 ?" a  if (num-cars > count roads)
; p8 n; d1 q+ i4 Z/ ]6 s  [% w: K9 H: j$ F9 P2 @8 z0 f
    user-message (word "There are too many cars for the amount of "3 u7 r% {, q/ R/ m
                       "road.  Either increase the amount of roads "0 j8 a) b. z, H" Q* z3 q& H2 H  O
                       "by increasing the GRID-SIZE-X or "
/ \& P( ^$ S) |  v0 S9 }( }! M                       "GRID-SIZE-Y sliders, or decrease the "0 R" ]; w, A2 v) O7 B( ^/ _) p
                       "number of cars by lowering the NUMBER slider.\n"2 f" H: J/ a1 L5 F$ w
                       "The setup has stopped.")' ]; b5 `! u" ~4 O: S, o) h
    stop5 |, T  n& Y3 ~: b; z
  ]
3 y5 H: T: _: b5 V$ l$ B' U
/ q* x3 s( @" M7 v! H  ;; Now create the turtles and have each created turtle call the functions setup-cars and set-car-color
/ n) h* S( x6 Y1 p5 L- w; i  crt num-cars
9 m7 |4 D2 S' L/ q$ i  [4 c/ S- k  f% @1 P1 p& V1 ], _
    setup-cars
" \  j) u' ~' F5 [6 P6 j6 S    set-car-color
$ k: r9 T4 \$ o7 O, Z    record-data' ?9 t3 H2 z* v7 y0 q1 `5 x5 ~+ P
  ]
: @  A( f# K' K: b0 R
$ z; `$ }! G8 \: [6 H' Q* `+ ^6 f  ;; give the turtles an initial speed1 M  u8 S+ W) a9 C! @5 z
  ask turtles [ set-car-speed ]
2 i/ c4 z  B1 `; Y- D, q+ d% t& c( ?  Z8 B' ~, l
  reset-ticks- H# g7 F0 R  h0 P. i
end
# F+ D3 ]- R7 |, N4 U5 _8 m7 ~! H& L1 r% o( W- k# O( @1 y$ m4 `
;; Initialize the global variables to appropriate values
* S- {0 m! ~# V' D# `' v8 Qto setup-globals
: n# H0 X' t; f. j4 Q  W% X4 g/ A  set current-light nobody ;; just for now, since there are no lights yet
: w0 \$ x7 w4 D  set phase 0
+ X' k- K1 V5 V6 W1 s  set num-cars-stopped 0
* t: L1 E1 H0 A  set grid-x-inc world-width / grid-size-x
6 Z& R5 O6 G: [3 n9 f/ `* G  set grid-y-inc world-height / grid-size-y5 Q" M8 E* U8 [* f2 @$ c( J
* M1 [/ g+ m6 P
  ;; don't make acceleration 0.1 since we could get a rounding error and end up on a patch boundary
/ i5 y5 ~) Q! S, K7 V, Q  set acceleration 0.099
- W; o/ \2 q8 ^- T4 d' a. R: uend' N6 Y& v6 D$ {1 O' C/ u

( A) G* W# X+ f! e* I( z;; Make the patches have appropriate colors, set up the roads and intersections agentsets,
0 w, Q# x1 K! d5 |, c' \7 p1 [3 S;; and initialize the traffic lights to one setting2 c5 i( K$ G' L! F3 U% _8 X
to setup-patches
& N% E9 |% S6 L- T  ;; initialize the patch-owned variables and color the patches to a base-color
+ [5 A, O3 c, e; O2 ~  ask patches
+ b3 Z4 R; R9 z3 X/ v  [
' a. V' |5 N. y( ~* D    set intersection? false
3 i, S3 X9 N" T% b4 t    set auto? false
1 ]' `% z* F, m. C( a- E6 f8 |" k    set green-light-up? true
4 h1 k0 s# b+ T7 \/ F    set my-row -1
) D+ ?; U. w/ w# X& v3 ~% `    set my-column -1
- a/ K  T0 P2 t. P& m5 q6 L- z5 I1 C5 t    set my-phase -1
2 M4 [0 s$ l; k1 J! j4 l; N2 _    set pcolor brown + 3
4 S+ E) q7 _/ k7 ]+ v4 j! [  ]
) s2 E, b# y4 d0 n6 Q; e) U4 L' S) g. E& f) S, A% C3 H3 [
  ;; initialize the global variables that hold patch agentsets
0 @- `' U; |' ~4 P  J5 v( H0 x  set roads patches with4 y+ D7 j8 T7 Y8 D( m  v- p
    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) or1 k( ^8 y2 \5 {' b6 ]0 R; R
    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]
- V* I! y! m4 {% `3 ^* D+ P0 x1 ^  set intersections roads with1 d/ T8 _- A" n+ |
    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) and9 w& m& k2 ~) ^- `( ]( s$ i
    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]
6 j1 x  d* m/ `0 z! r, h. C6 k! V" c! c9 ?
  ask roads [ set pcolor white ]
' n7 c$ }3 E+ @7 }7 u( `    setup-intersections
8 S1 T' H0 `- w4 Jend) L! N5 S* g$ O" d- l3 K! d9 }/ x
其中定义道路的句子,如下所示,是什么意思啊?$ C" `4 B2 C$ j: n
set roads patches with
5 H' u8 ]) ]" m3 z' w* Z) h% L    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) or
9 U6 }7 b4 `! v    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]
( Z' H* N2 r5 q$ [2 Z3 Z% v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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