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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。4 ^2 I2 D5 q  S( L" _, V# X4 c
netlogo自带的social science--traffic grid这一例子当中,
; k9 C9 r) @  h9 Wglobals( Z: \, W  t+ D
[
. }6 R) w/ Q/ i( j4 v' V5 H5 l  grid-x-inc               ;; the amount of patches in between two roads in the x direction
$ F  ?$ W' O" g7 v  grid-y-inc               ;; the amount of patches in between two roads in the y direction
4 a8 p+ O. |9 h: I& N- q  acceleration             ;; the constant that controls how much a car speeds up or slows down by if4 I2 e. {8 ]* k2 F1 t8 L8 U7 T
                           ;; it is to accelerate or decelerate" o7 E4 W% o4 \  X* U! F
  phase                    ;; keeps track of the phase
! o# Z, Z  M5 Y+ @2 h6 D' r  num-cars-stopped         ;; the number of cars that are stopped during a single pass thru the go procedure0 S, ~) @: T0 A0 u- Z
  current-light            ;; the currently selected light
7 Y& @4 ]5 ?% g8 N
3 K0 h+ S2 A# R3 a' d/ D  ;; patch agentsets
6 v# L# h5 X- m+ Y0 _- D9 u  intersections ;; agentset containing the patches that are intersections
$ j$ K9 }: x" ?' W; j  roads         ;; agentset containing the patches that are roads
# C9 k4 J4 M; t; W- z, }  g- n]* X5 T2 `8 M3 s( J7 {

% V' h' m  {+ o- Cturtles-own
7 ^- v8 \3 q. G- @& C[0 S3 i# ^5 P% ~" z7 u  G
  speed     ;; the speed of the turtle% z; d9 [# H" i
  up-car?   ;; true if the turtle moves downwards and false if it moves to the right5 P1 B3 }) k! j! }7 `
  wait-time ;; the amount of time since the last time a turtle has moved
. w) d2 W$ _! L% E8 [. G4 A]% W/ L7 O) F! r% B

- J8 x+ h, ]) e' r  X9 R3 O( E- {patches-own
& J& W& x  f$ ?8 Z; q4 F6 A! V[
- |# p1 \! P' A, [- [8 D# e+ z5 l2 c  intersection?   ;; true if the patch is at the intersection of two roads. L; S3 \6 b9 g. T' V
  green-light-up? ;; true if the green light is above the intersection.  otherwise, false.% d/ o% U5 H2 C: p4 g
                  ;; false for a non-intersection patches.
8 j  H8 T: Z1 u5 i: ]/ Q' `* G  my-row          ;; the row of the intersection counting from the upper left corner of the
; V( M6 \! {9 I! w4 O+ R                  ;; world.  -1 for non-intersection patches.
: _! y3 @5 L: t  my-column       ;; the column of the intersection counting from the upper left corner of the$ B9 A: k( e; b6 ]# H" Y5 ^5 W
                  ;; world.  -1 for non-intersection patches.: a- L  O2 h; @3 w8 p! p5 E, z+ C
  my-phase        ;; the phase for the intersection.  -1 for non-intersection patches.! N, G4 }" x* l# Y6 C9 n( B6 ~
  auto?           ;; whether or not this intersection will switch automatically.
9 x1 C0 H; J( ?                  ;; false for non-intersection patches.
* z2 d% D+ G# l5 [: s" R2 l% w]  w) V% L& s' y

; M& ]) p, K5 Q& k) D) l4 l* m0 c
( |" K$ f$ N" t  m5 M6 j) v;;;;;;;;;;;;;;;;;;;;;;/ w, K5 f: I$ S- [" m) D) b
;; Setup Procedures ;;# W0 s3 x1 q$ a( |& `
;;;;;;;;;;;;;;;;;;;;;;- H5 K# n% i- N' t' v: x
$ W  O" y2 @6 @, t: r
;; Initialize the display by giving the global and patch variables initial values.
# p4 }  e9 M9 k4 F" h, @" _5 e;; Create num-cars of turtles if there are enough road patches for one turtle to
4 \; w; E+ |- m: e% q6 M3 Z  _;; be created per road patch. Set up the plots.
# q) M1 @7 O  G& N# P4 I5 Ato setup4 G0 l3 V  N$ K# l! J
  ca( I3 J5 Q. N  J$ W( _
  setup-globals- {8 i# l! W, P
! m' V: h, }% ]1 l4 T; E
  ;; First we ask the patches to draw themselves and set up a few variables6 n! v( ]& P5 }
  setup-patches) O& o6 b6 j) F% _
  make-current one-of intersections
5 }, p) Y0 f3 I/ g* S0 k  label-current) i( q8 C" K7 d2 R3 y! ?6 q, P
4 U/ F" }7 b; ^3 _6 _
  set-default-shape turtles "car": ~8 U  W" z. j$ h! N( s  m

  }7 G+ S5 \0 f  if (num-cars > count roads)' e3 z! A- ~+ C5 b3 ?+ C' G: j
  [
6 z6 d" G4 o% P1 k    user-message (word "There are too many cars for the amount of "4 m5 J& ?6 P( |3 p  r
                       "road.  Either increase the amount of roads "
  B: E" C- e4 o7 I                       "by increasing the GRID-SIZE-X or "
0 W+ b& `* D! J                       "GRID-SIZE-Y sliders, or decrease the "
/ @( _: c7 i) n  q                       "number of cars by lowering the NUMBER slider.\n"! h' E5 Z8 P9 d7 G: p) \6 `/ p
                       "The setup has stopped.")* O- n: Q1 k+ p* _
    stop
- r# T7 c- k5 Z3 b: p$ q  ]4 ~- y+ p2 M: \6 @9 n0 N' }

% l9 A5 }& r0 S  ;; Now create the turtles and have each created turtle call the functions setup-cars and set-car-color* Z; _5 ~. H9 k
  crt num-cars  x4 ~$ ^* T" _. C) `
  [
0 n  o5 g3 K3 b. O  D    setup-cars8 [( @+ ^% B: _6 U( s8 \
    set-car-color7 B( p% ?( Z- f/ r; u$ U% @
    record-data$ k) V# t8 c7 G
  ]% t# b! `; l; O3 o7 c* o

& [$ J9 D' ]/ O  ;; give the turtles an initial speed+ C9 |3 {: R; n& z
  ask turtles [ set-car-speed ]
& o( r. a) ~: T% g( l' R* n
& e+ l4 J$ D( X; a) Y  reset-ticks; ^1 T( F6 ~. F7 k; t
end
( r; G! z  {' V, Q
- D' F$ A7 W* {0 y0 z9 g/ l) h9 j;; Initialize the global variables to appropriate values
+ V- R1 X( W2 q2 g( I, Rto setup-globals5 L+ t; N, p: A7 q9 @2 K" S
  set current-light nobody ;; just for now, since there are no lights yet, E6 e" P0 ^, I4 }5 H
  set phase 0, _; w/ W* z, F3 Y5 c! @& p! C
  set num-cars-stopped 0
6 u* C* ^2 w) Q5 N  set grid-x-inc world-width / grid-size-x
, O' E2 E0 B3 z  set grid-y-inc world-height / grid-size-y
( C9 Q8 w1 c4 n  q" V- x/ W
. F( {" F7 H  n; B8 X  ;; don't make acceleration 0.1 since we could get a rounding error and end up on a patch boundary1 I5 ~/ {3 P: Y4 f
  set acceleration 0.0998 J4 H. v; F7 Y( l( l
end6 M$ U- E% z* _; z4 y$ y
! j2 q6 I3 k! `- l! Q/ l* w
;; Make the patches have appropriate colors, set up the roads and intersections agentsets,
5 R2 \* |- O7 m, Q: V3 a6 n;; and initialize the traffic lights to one setting; G# K) |  g. ^9 K5 a* @
to setup-patches
; v4 H3 Z5 G1 r; Q( F2 K2 l6 Y  ;; initialize the patch-owned variables and color the patches to a base-color
% Q0 `* A# p$ R* ^' `* t8 M$ }  ask patches& J  ^3 j% t" L0 R" Y, w6 L
  [
) w5 l# l, J8 P0 }9 s, [+ |    set intersection? false1 D: {7 M' T" ]
    set auto? false+ t: S: t9 V+ l2 K1 _( }' a
    set green-light-up? true
2 ~  F" b) h! d  K: t" `" A    set my-row -1
+ A1 B- p! H+ q7 i2 d& J& n    set my-column -1
; v) R) V$ D3 J4 f    set my-phase -1
+ r0 G2 q$ ~: Y% j- q    set pcolor brown + 3
* C6 m% {  a+ ~# C/ Y9 k. H  ]
% A0 A8 V5 G0 U% K
9 ^8 i0 v" G, q& y3 }" z! O2 }  ;; initialize the global variables that hold patch agentsets
6 f0 i/ _9 M0 T% A  l4 N$ e9 }  set roads patches with
+ _, t0 r  ?2 s1 q# o/ q    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) or
. k+ @! R- t: F9 y2 @    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]
5 `) [, H7 f& D! ^: K  set intersections roads with
& j" m! F( M. C* B7 ]/ ]! ?& F! ~    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) and
5 J1 U! L  |- J7 O) n7 j4 [    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]. D- F* D2 v' O7 S4 o/ u+ a
! p- t* _1 N" A: _; A2 F# D* r
  ask roads [ set pcolor white ]* Y0 _6 E, d' u6 t
    setup-intersections$ k3 n8 d( r, Z  t' h0 @. J, d
end
% G) Z/ X* f8 }) U其中定义道路的句子,如下所示,是什么意思啊?
3 `3 D7 E0 }- ^6 J3 I set roads patches with
# d; t% w, ?# I' _2 q$ X( K    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) or1 {) K4 Z6 m8 H
    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]
7 R( ], X  t+ p- ~. ^- l+ 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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