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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 j' f9 w7 P! X% g
netlogo自带的social science--traffic grid这一例子当中,
, t  e( W4 U7 E) m1 Bglobals; O7 N  J5 n- z8 I) q, w5 V' z
[# `4 h9 g4 Z6 G; v
  grid-x-inc               ;; the amount of patches in between two roads in the x direction
7 ~+ W8 W! G! r- J4 K  grid-y-inc               ;; the amount of patches in between two roads in the y direction+ \" p4 Z  t  a
  acceleration             ;; the constant that controls how much a car speeds up or slows down by if
3 i# ^4 y) l6 r0 b2 V) x                           ;; it is to accelerate or decelerate
. _3 |& X8 ~) Q9 W  phase                    ;; keeps track of the phase" q5 l5 e' c" g( w9 S4 A
  num-cars-stopped         ;; the number of cars that are stopped during a single pass thru the go procedure6 O5 z7 t( |) d3 U) o8 C* _+ x
  current-light            ;; the currently selected light7 M; Q- _" P8 S- W3 H9 T5 z* s' a
( s7 V5 c5 d7 ^- y) J
  ;; patch agentsets4 N! u2 r% Z1 p
  intersections ;; agentset containing the patches that are intersections% F" p; @, a. f" |0 G! |
  roads         ;; agentset containing the patches that are roads
' x. i: u/ k/ U- D: N- ~]5 ]1 ^& B6 z. }" J1 u1 f
: x3 @4 @1 L7 A$ e% E+ O
turtles-own* H  W8 N: \/ }) l
[
; V- n* K; A+ F: a* M9 p2 k4 x  speed     ;; the speed of the turtle
0 S' O. d8 ~9 M4 n& u  up-car?   ;; true if the turtle moves downwards and false if it moves to the right8 Q3 f# m) {: H6 f
  wait-time ;; the amount of time since the last time a turtle has moved
7 o4 S; @- O% p5 q8 m]
# Q# e6 m7 ?7 k
$ [0 y% P$ O! Ypatches-own% p1 [# M3 H' y% _4 l$ t, P
[
; C' ~, N# _$ V0 l  intersection?   ;; true if the patch is at the intersection of two roads
6 [) z. b- M) Q  green-light-up? ;; true if the green light is above the intersection.  otherwise, false.( ]8 k5 }' M6 I2 G
                  ;; false for a non-intersection patches.0 n% N: {4 B2 g! ]6 y8 b, O: a2 ]
  my-row          ;; the row of the intersection counting from the upper left corner of the
- q/ q6 T) k9 t1 X- s9 k9 K" ~  E- @                  ;; world.  -1 for non-intersection patches.
9 K7 v9 C" u# T5 S, r0 d  my-column       ;; the column of the intersection counting from the upper left corner of the
+ M$ L# l" F9 S                  ;; world.  -1 for non-intersection patches.! X9 C3 G% ^( a4 f! F' I! }
  my-phase        ;; the phase for the intersection.  -1 for non-intersection patches.* j% |" F: y4 F* C& ^
  auto?           ;; whether or not this intersection will switch automatically.3 G: J$ b; M9 c% G& h2 Q
                  ;; false for non-intersection patches.
; _! d$ |( m$ }( h- M% A) J]
4 m* x: [1 h# S' Z8 ^! d
0 W4 ?) T1 K% W
# k- F! f* |8 A& E9 ~0 _# O& ~4 ]& W;;;;;;;;;;;;;;;;;;;;;;
+ c8 ~) D, w# j" K( c: j- V1 I;; Setup Procedures ;;
7 C( @0 T' b4 i# Q/ \& g) M% c; n8 M2 n;;;;;;;;;;;;;;;;;;;;;;
6 |/ E, Z. @: `+ R, M& J% @0 V/ `
;; Initialize the display by giving the global and patch variables initial values.
; N0 }0 l+ \" S, Y;; Create num-cars of turtles if there are enough road patches for one turtle to
) u  `' j, [1 x8 s;; be created per road patch. Set up the plots.
1 g4 u  e. c0 _0 q$ `0 w# p+ Sto setup0 ?' z2 n) H1 T/ Q2 F
  ca& Q. M7 f$ a- l1 U% i' B
  setup-globals
/ c/ S3 k2 ~4 w8 ]6 j
, t/ u+ ^  |' |: y% x4 A, c! X" H  ;; First we ask the patches to draw themselves and set up a few variables& W; l+ \9 V. W# A# W+ p
  setup-patches, Z" e( U' j- y, t
  make-current one-of intersections; ?8 o. L" x+ a
  label-current* }5 y1 U1 q. m8 ^/ A" B

7 P6 y: g% v9 @9 p1 Z  set-default-shape turtles "car"
) H4 V2 s! v; ?1 o4 Y# q1 F$ f
" s2 S$ N8 K) j% A  if (num-cars > count roads)
& M% z& s* t: y0 ?  [
5 e- |3 a6 L* e; B: M0 L    user-message (word "There are too many cars for the amount of "
6 p3 m/ y, D6 M- ~0 Q  e5 Q8 @$ A/ B                       "road.  Either increase the amount of roads "
) Z! F, i/ X, C6 f8 r8 Q: r& P                       "by increasing the GRID-SIZE-X or "
* \$ `" c: M6 P% w5 c9 E6 _6 ?                       "GRID-SIZE-Y sliders, or decrease the "
8 _/ y/ \5 p8 b2 |; L- L/ [, l                       "number of cars by lowering the NUMBER slider.\n"" e2 |6 z) _0 J1 F
                       "The setup has stopped.")
' P! u$ Q+ s" E% ^8 f1 n    stop
( j' y" c' m0 z) ~6 Z1 A( j  ]
* T2 v% ^* O- n( m! |6 O7 O% a0 s' ~3 q, L8 V, k
  ;; Now create the turtles and have each created turtle call the functions setup-cars and set-car-color
& B' _8 w  I) ^  crt num-cars
+ h4 ~+ W" p% o, @( }* e. G/ D  [/ L% D9 d4 W7 p- R  k
    setup-cars4 R9 W8 c1 {$ J5 ~
    set-car-color
' e( Q# L: `5 A    record-data
  Z% J% h+ l4 Q( s( _4 C  ]* m$ M/ k6 C. O

, ?2 `) ~$ g" b9 E& X) a; X  ;; give the turtles an initial speed
- E+ i# m0 \9 n* Q" d  ask turtles [ set-car-speed ]
4 j; c. e$ m3 M" ~- }" v. B# Q* k2 ]8 v
  reset-ticks
" u4 r4 R/ n# a" O2 O- gend" h7 Z* _6 n/ R4 W7 l

% N3 R9 i! z: D& B;; Initialize the global variables to appropriate values
. y; s) S0 D* t+ L' y8 Z: n  {6 xto setup-globals
4 h+ l4 |' l" G- O3 D7 P; d  set current-light nobody ;; just for now, since there are no lights yet) v0 B; T+ r% A5 a* k7 ~7 D$ ?& Q0 z
  set phase 0
+ `1 [) B; q% W: k7 s: \( s  set num-cars-stopped 02 Z% y8 a& s, l; z! F
  set grid-x-inc world-width / grid-size-x9 ]: w! w' C/ A  T- C- I$ E
  set grid-y-inc world-height / grid-size-y
7 q& W. Z( j2 ^+ @8 S, r
: q0 ?( r6 C0 z; W6 F3 P1 K7 T  ;; don't make acceleration 0.1 since we could get a rounding error and end up on a patch boundary6 M* k' ]0 n$ k2 C7 I& Q0 E) c
  set acceleration 0.0998 G6 Y% `0 K2 j/ J8 K# \& g
end
/ T: {, |  Q! |% V. i& k6 a! j
5 @5 f3 y: u4 T+ F, [;; Make the patches have appropriate colors, set up the roads and intersections agentsets,; N9 ^! ^7 e  E" w
;; and initialize the traffic lights to one setting
# X# G) m  u/ \9 [, V3 ^to setup-patches7 c0 t  u4 t4 t
  ;; initialize the patch-owned variables and color the patches to a base-color
2 P2 Y0 K1 a8 W4 S  ask patches
. b1 H& D; x+ x; J; M) O  [
  w# d3 v" d' K/ T% }1 P3 D) Q8 D    set intersection? false! p+ w; J! }6 n$ r* ~7 ~
    set auto? false
5 t6 m( \( [- U4 q' @' M7 w    set green-light-up? true
, M; o" e$ \% i; t" K% @, ^    set my-row -1
% J; {% {: y) L: D& h, `    set my-column -1
/ K* q, e! X/ ?* r" \5 t    set my-phase -1
; S. }8 R1 F8 f' C    set pcolor brown + 3  j2 H/ M' S3 U8 {% }8 j
  ]
" {1 B! O3 |. J) m6 v  s! W2 s! N# z6 G9 k6 c% n7 b
  ;; initialize the global variables that hold patch agentsets* C5 |1 j( \* P" Z' F
  set roads patches with" l2 x5 F* U8 l5 }; r* \+ g
    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) or6 G: @6 l7 Z3 b  ]
    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]& E+ w5 }3 E; c2 P3 Y/ O2 C
  set intersections roads with
: p( C1 E( K6 B) b+ I' w1 z    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) and+ N7 f1 h) ?- ^( P
    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]; O' D2 d  h; V* q8 u

1 @7 ~6 w. N0 ?/ @( R0 }) p/ B3 \  ask roads [ set pcolor white ]1 |- k  j0 z. i( c( G
    setup-intersections% I2 j+ ?& |6 F# n2 O
end! v$ Y% ~, Z$ L+ g
其中定义道路的句子,如下所示,是什么意思啊?
4 z" v, U# S$ R/ G! R/ Q set roads patches with
2 E2 G# ~$ e2 p3 m4 T. l$ B    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) or
8 q5 F& y1 D9 B: F    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]0 u* H( C- ?& N
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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