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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。2 }' Y/ b. }8 w3 c) ~( m
netlogo自带的social science--traffic grid这一例子当中,
, D4 A# g, P( eglobals+ C: b% H  v6 N7 F
[
. L, [% u  H& t  grid-x-inc               ;; the amount of patches in between two roads in the x direction
) E% f# V1 G; o' e) ?: r4 J5 C  grid-y-inc               ;; the amount of patches in between two roads in the y direction
: }* w& {/ j* h; g% }9 x  acceleration             ;; the constant that controls how much a car speeds up or slows down by if/ r. `, W" A1 g! Q4 z
                           ;; it is to accelerate or decelerate
5 o' p! k3 m6 y  phase                    ;; keeps track of the phase
# A, E, p/ b, S$ K3 ?  num-cars-stopped         ;; the number of cars that are stopped during a single pass thru the go procedure4 t( E% ?: P6 v* Q
  current-light            ;; the currently selected light1 J* t2 U5 r# e/ k& Q7 }
, e6 k! U' E: X3 y6 u; h. K
  ;; patch agentsets; q" N# r' B# i! S1 T+ i$ W0 d
  intersections ;; agentset containing the patches that are intersections
) \( v* _# z  ?& ]- i3 t9 b: t  roads         ;; agentset containing the patches that are roads3 l5 g* U7 @; {8 ?9 }% ?- S& Y! K
]
1 g; W1 F6 ]) U1 f" W: T5 ~- L6 D3 Q
turtles-own& w( n3 J, H* u8 l+ L5 R
[
6 V* C7 M4 g/ J5 @; n% r  speed     ;; the speed of the turtle5 i; Q) I" T* ~5 Z. @( g
  up-car?   ;; true if the turtle moves downwards and false if it moves to the right- Z- w" Y8 S* _, D7 f
  wait-time ;; the amount of time since the last time a turtle has moved
; x/ S& n# K) Q! N& s) l. r]
1 U" j5 s+ n- t% \! c: T
$ d6 B/ S! ~% Y" b2 D" o1 b: Xpatches-own
! c# \4 M& J$ r2 c[
# d! X9 s+ P1 F) ]  intersection?   ;; true if the patch is at the intersection of two roads
- C/ T8 z1 K9 i* R  green-light-up? ;; true if the green light is above the intersection.  otherwise, false.2 h( Z9 ?5 i! K: A0 y* T* l* u$ W" q
                  ;; false for a non-intersection patches.
/ z/ Q& S; |# s. K/ ?; S  my-row          ;; the row of the intersection counting from the upper left corner of the; B. [( F8 e* ]0 ~
                  ;; world.  -1 for non-intersection patches.1 x  k9 Y! t$ I) v+ k7 x
  my-column       ;; the column of the intersection counting from the upper left corner of the
: h' T3 T) r/ P8 k                  ;; world.  -1 for non-intersection patches.
3 |. t4 q  _2 f- q* [" Q  my-phase        ;; the phase for the intersection.  -1 for non-intersection patches.
: O0 I- ]+ }! e. D: n  auto?           ;; whether or not this intersection will switch automatically.2 V: {6 x& S9 P4 F9 k: P* d
                  ;; false for non-intersection patches.
! z7 }: a- I) b+ @2 n: b& x; V]3 s5 e" l0 I; C

6 H/ q3 h. Y! M. @  j& e, u8 F5 E  M' W( v& z, E2 y% n% r& Z
;;;;;;;;;;;;;;;;;;;;;;) L5 `$ I5 I( V
;; Setup Procedures ;;: |) z. T  R% n' i8 W7 z
;;;;;;;;;;;;;;;;;;;;;;7 E- q" e  u5 O; o4 @

, t; C' W8 T* _;; Initialize the display by giving the global and patch variables initial values.
8 a1 }: l$ q* @3 N2 h;; Create num-cars of turtles if there are enough road patches for one turtle to
. Q- S+ w8 p, V  }0 I% R: W# y;; be created per road patch. Set up the plots.8 T" S1 c$ Z/ `- t. D6 W- ?5 f) @' s
to setup
9 ^7 j1 w! S* H* c( A' e  ca* j% r+ C, G6 J) i# ~
  setup-globals' v3 u! r1 b$ r+ F$ t# }: [
( v2 z0 E4 u9 l& s& b+ b9 K9 U9 s
  ;; First we ask the patches to draw themselves and set up a few variables
5 a# X2 x1 a& K$ c0 H) R  setup-patches
2 P' q/ V0 O7 o" G4 a" w; m8 _' G, I  make-current one-of intersections
1 n! [/ x* @; n. p! J  label-current1 t# |. g( i& j' M
( d% d  t# T0 K! I5 A, ?3 D
  set-default-shape turtles "car"
" \- }0 r3 s% r% Z4 q
& Z4 [; r. L$ b- N  if (num-cars > count roads)/ x6 Q% i( M% J$ v( L! m
  [
- P5 U! S9 p" k/ |    user-message (word "There are too many cars for the amount of "# B% G9 f! Y0 J6 k
                       "road.  Either increase the amount of roads ". s5 P" }+ [7 J$ U  n" R, H' e
                       "by increasing the GRID-SIZE-X or "" L8 Y& @' \) z# b$ C! X1 X
                       "GRID-SIZE-Y sliders, or decrease the "
& e1 S* h, v+ L' b) k                       "number of cars by lowering the NUMBER slider.\n"
3 s' N/ I; z) Z9 u                       "The setup has stopped.")
! L* i  E/ }! J( }4 Z/ @$ C* Z    stop2 G* ~7 p- h9 Y  G! u( }
  ]" }- L' ^8 u5 W' k2 L

  y' C/ G* K  M8 S  O  ?$ F  ;; Now create the turtles and have each created turtle call the functions setup-cars and set-car-color4 A$ a7 c  t  k; w
  crt num-cars* k& `; m  b$ f. b. Y# U% k! b  }1 M
  [
* @6 i9 S7 [+ |/ E2 J; U    setup-cars
5 `. L% L' g+ @9 @    set-car-color8 v2 d- t1 M8 P) {: G! [8 B
    record-data
& `6 x- ]# L' {) N- I6 ]! K  ]5 q: S- Y' c$ I! n" d" g

7 `8 t- K$ m6 e. F  X1 W/ ^  ;; give the turtles an initial speed
7 ^% J2 z3 m" k7 k% h% n% Q  ask turtles [ set-car-speed ]
5 s+ c, ^! [% }' S8 ^; K$ |9 D! a' p3 e$ {5 L( u7 X
  reset-ticks
  H5 i2 f/ i* `8 B. x0 k2 `; Eend
- e! P& f4 z$ r6 b' I% b1 }7 m
: j' W; d: z; h( s+ `9 N6 P;; Initialize the global variables to appropriate values
) @9 g% ?( W# g' @+ u+ lto setup-globals
3 ?, \, }- l% m8 w" A  set current-light nobody ;; just for now, since there are no lights yet
& w6 A, H. }) w% I$ W6 k  set phase 0; J; h$ r& @+ Y0 u
  set num-cars-stopped 0
: ~; ~1 u5 c# `6 n2 i- h  set grid-x-inc world-width / grid-size-x
& f: E- h/ Q9 i: d3 Q2 I* t  set grid-y-inc world-height / grid-size-y# w" E1 e( {4 R3 `* G

. s' p: x# J9 y1 R  ;; don't make acceleration 0.1 since we could get a rounding error and end up on a patch boundary3 A0 G' H, G: G
  set acceleration 0.0993 |, x% B7 z9 E2 D+ |
end6 ~/ L3 X3 F/ @) Y
$ a' i) p! d3 ~7 T
;; Make the patches have appropriate colors, set up the roads and intersections agentsets,
" ]$ A1 A' K% U2 f6 n8 ]: B) p;; and initialize the traffic lights to one setting
0 G# b+ D! X9 `5 Gto setup-patches
2 f# b* c  ?! x% Y" y  ;; initialize the patch-owned variables and color the patches to a base-color
; K) ?- J9 _/ c) [4 x- `# Y6 U  ask patches8 b; L. T1 m, {) T: c& {* s
  [
6 X  P4 Y' n1 H- x" r. U4 |    set intersection? false$ r5 B3 r0 B: Z3 \, q9 P1 [
    set auto? false% O& h0 w' ~. d0 w9 C0 S. M
    set green-light-up? true) h4 u$ E& E, r! R
    set my-row -1
$ N' |6 X3 N: x: @5 k$ n# Y* r    set my-column -1
9 r4 _$ m* ?0 O4 C/ t9 O$ G    set my-phase -1
" p- y' _+ [$ c& a    set pcolor brown + 3
$ E. w/ ?; }) J: a: p+ K/ i  ]
/ J# Y6 i7 D! N, Z" n8 k1 U0 S. u7 v6 ]# `9 I
  ;; initialize the global variables that hold patch agentsets
4 c& }7 |. w! u# P% h3 V  set roads patches with! m, F- o0 }* d( E, G
    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) or
* L# @! W6 _2 o3 w    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]7 Z0 d( f3 y  ~9 N; w, z9 ]
  set intersections roads with) Z2 G1 H) y! D* Q, B- C
    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) and
9 Z3 G) N' Z6 W# Q4 A" X; u2 h& E    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]
4 B& p6 H3 u; d* [5 e
% S- J$ K3 d- ~: L8 z8 M" S4 o  ask roads [ set pcolor white ]. q3 f5 E5 ?* A$ [( a, [* c
    setup-intersections
8 |9 M9 i, H9 s6 N6 j" ?; ?end* O& {3 |1 F5 a3 F6 u# ]! P
其中定义道路的句子,如下所示,是什么意思啊?
, |$ ~; l2 z6 H  [ set roads patches with" N& U: A. N$ s8 T
    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) or( ]! z- P! Y; F+ A
    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]+ k4 Y. C; s# M& k  P; b. }$ z
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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