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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。3 n6 `' s- f9 s9 D
netlogo自带的social science--traffic grid这一例子当中,
9 U; t6 W1 ^- w& q' Aglobals7 s+ \) w- r: n- W" m
[
8 i) p9 b& o8 w  grid-x-inc               ;; the amount of patches in between two roads in the x direction
4 X' @+ p) v7 I# u1 V1 J  grid-y-inc               ;; the amount of patches in between two roads in the y direction4 J% U8 n% h5 H. M# R
  acceleration             ;; the constant that controls how much a car speeds up or slows down by if
" d) e6 I; C) R/ D$ P) d! w                           ;; it is to accelerate or decelerate& b7 r# P$ P# I( _; a! N. b+ [
  phase                    ;; keeps track of the phase. H$ E) C2 i6 p$ p
  num-cars-stopped         ;; the number of cars that are stopped during a single pass thru the go procedure' T9 A: Y8 T9 X' e4 ~6 k- f
  current-light            ;; the currently selected light
) v5 _, N& V, ^$ V  y
. O  R4 M5 R  P  ;; patch agentsets. P, P1 G) I6 v1 u- S
  intersections ;; agentset containing the patches that are intersections# M! z0 B* v  d$ _/ r1 b5 y7 I
  roads         ;; agentset containing the patches that are roads- i' s! C: ]3 g4 N1 H5 e
]  _  q$ N! r# z. ^- M6 I
$ S  e6 d& k& f' a# D- G; y, q
turtles-own% M2 ^+ o) z$ x. A8 k+ ~' `( h
[
# U& W! B1 f* }, k  speed     ;; the speed of the turtle
' u4 _! ?' r3 z. b, _& A% K  up-car?   ;; true if the turtle moves downwards and false if it moves to the right
7 i/ o) `7 M$ j* E7 r7 p! H/ g  wait-time ;; the amount of time since the last time a turtle has moved
( c5 t2 ]) [6 `$ v]) e& M! ~3 p. \. W
# |7 o: u$ X; a$ H; y7 c
patches-own
0 O% i8 H& o$ Q% R/ C# G$ x6 f[
' f6 ?  \! R% b/ k  intersection?   ;; true if the patch is at the intersection of two roads8 E0 o6 p5 J) W
  green-light-up? ;; true if the green light is above the intersection.  otherwise, false.
: K6 b# t% b( u; x6 Y8 Q. f                  ;; false for a non-intersection patches.) M8 Y/ F; ?6 C
  my-row          ;; the row of the intersection counting from the upper left corner of the4 r/ h- c! y0 V. X( @
                  ;; world.  -1 for non-intersection patches.
4 o6 O" M2 b* B9 {' E% {; v4 n  my-column       ;; the column of the intersection counting from the upper left corner of the
, E6 F0 |* l- P4 B0 F                  ;; world.  -1 for non-intersection patches.% m/ W+ |# B* W! G& ^1 Q8 t+ R; Y! I
  my-phase        ;; the phase for the intersection.  -1 for non-intersection patches.
4 S8 Z& w0 V, M/ I9 s2 H' d  auto?           ;; whether or not this intersection will switch automatically.
/ ^1 L, G* f. x4 ~% h: B& g                  ;; false for non-intersection patches.
, D" x2 e% v# p, |! \]. N# R% |3 {( y4 w

  i3 k6 O0 m" g- h6 y" L0 W, M8 z- [" Y& `) }+ z( n' p0 c
;;;;;;;;;;;;;;;;;;;;;;
' V/ P, r% S1 `/ p$ m0 X;; Setup Procedures ;;8 |6 h' r: c) p4 t: X
;;;;;;;;;;;;;;;;;;;;;;
. e% a' R, }! x" ~4 J# p8 Q% ~% j4 f3 I3 ]$ I1 Y; l
;; Initialize the display by giving the global and patch variables initial values.
  t2 u! \1 Z3 x4 ]/ E. {' Z;; Create num-cars of turtles if there are enough road patches for one turtle to, r: u/ g* n; ], D5 Y4 ~
;; be created per road patch. Set up the plots.8 m/ \1 C2 U* F
to setup; I. `7 l! `/ T& P
  ca
$ g  [: x% p: b- s8 O  setup-globals
; p. W- P1 @% e! p
5 U! e/ Z4 _/ a9 C  ;; First we ask the patches to draw themselves and set up a few variables* \$ x. u; m$ f$ G. }0 G5 x4 V
  setup-patches
# X2 J. t/ b2 ?* _; I" u  make-current one-of intersections
& A6 o; }! W. t2 s" j( I2 {* S  label-current
$ d: k/ j. I" Z  y' {. I
  z( S9 K% n/ Z  set-default-shape turtles "car"
  O' J; p+ Q3 y% R) c" s% U/ J7 Q6 h0 J
  if (num-cars > count roads)
: Q; [9 K9 E2 f, x8 H  [2 o( x7 P8 t. u9 b$ E* K9 U
    user-message (word "There are too many cars for the amount of "1 a3 K' r2 S7 u0 j
                       "road.  Either increase the amount of roads "
/ C0 b% A' i9 E- V                       "by increasing the GRID-SIZE-X or "9 h; U% c1 L! P- h: `/ `) D
                       "GRID-SIZE-Y sliders, or decrease the "! Q3 y7 z9 t; H$ d, Q3 l6 W
                       "number of cars by lowering the NUMBER slider.\n"
0 C/ @- `9 f. ^                       "The setup has stopped."); L' [: z% U; z" M0 I! S( G9 Q7 L! z2 d
    stop# W* ?$ ?  G, D' l8 ]; S
  ]
- Y6 E. v# z  c# R0 t
. R- l8 e% T% M" s* Z  ;; Now create the turtles and have each created turtle call the functions setup-cars and set-car-color
7 ?; Z. M5 y/ o9 J; N# D  crt num-cars
; a: u2 @* h9 C4 v( V7 {' J  [8 u3 t  V8 V) x% M- e
    setup-cars4 i/ Z% k+ W) a& |9 E
    set-car-color7 B* K, A% u5 |
    record-data5 X* Z$ J5 c. ~3 ?* F! {
  ]) v! k3 M; Z8 i2 g: ?
4 @1 R8 a$ l( O" K7 f3 f
  ;; give the turtles an initial speed
5 o/ \5 E' W; H' Y! c/ s  ask turtles [ set-car-speed ]! s1 x' N: V7 u' _/ o, Z" }
7 s. r( M  C& ?$ t
  reset-ticks
) r2 Q# K6 W! {end
# s# s. Z' _, G. G0 Y
% ~' i9 o' }+ v& A" j% r;; Initialize the global variables to appropriate values0 T- @) M1 j% q  [6 W1 {& b" t
to setup-globals
+ q4 E: ]4 [* |  set current-light nobody ;; just for now, since there are no lights yet9 D9 Q- p' X8 U- s( H) O# x' p+ p- g8 g
  set phase 0$ c! B$ ~2 A. y2 s% t
  set num-cars-stopped 0
  P7 @$ b* A3 L* X, k  set grid-x-inc world-width / grid-size-x% ?& A2 s- V; q8 T4 x& m- e0 H
  set grid-y-inc world-height / grid-size-y
( T  m4 R0 b4 k3 l- v( k# \4 Y( w
3 {: Z0 b: l$ `% k/ R, }7 i1 o9 s  ;; don't make acceleration 0.1 since we could get a rounding error and end up on a patch boundary
# x4 N' `# p0 \  set acceleration 0.0996 `" Y  u: _8 \( q- `  |- |5 |
end! f, Q! R7 ^2 c  C. q9 `! }* E* Z
) M5 ^# z# `& ^% [
;; Make the patches have appropriate colors, set up the roads and intersections agentsets,
& U* e- D# V" o9 V8 [) g;; and initialize the traffic lights to one setting
+ y& e/ C0 W6 Wto setup-patches
( F1 q* J1 r* s8 |, H# J7 f  ;; initialize the patch-owned variables and color the patches to a base-color% Q3 N2 ~0 X& i# [
  ask patches  X2 a0 p. t$ R# c0 p2 \5 n; W
  [( Z! r3 o9 H/ ?: \! c; }# l: v
    set intersection? false* [% _/ S) D4 z# p. S' z& f
    set auto? false3 I. [/ e* c' k
    set green-light-up? true; ^4 a  n$ _! U6 b' E
    set my-row -1
3 `1 T" g  G" r    set my-column -12 v. b4 y/ ?! {. c; {; Y4 `
    set my-phase -12 t$ U3 Y1 q' L! G! i
    set pcolor brown + 3, `0 ?8 G. {7 w/ t+ x5 ^9 D4 `8 Y
  ]
3 o4 A5 L# F, i4 S& K8 P) c( F7 a( O8 ]
  ;; initialize the global variables that hold patch agentsets
5 t! o( m8 n$ a! g& T5 C4 o  set roads patches with% O  f, R2 i3 y  A. J
    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) or6 R& X  x$ X8 g, @: [4 m1 s& i/ Q3 l
    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]
2 N% e: w5 n! p- O( O  set intersections roads with
) {+ l, s& o4 H  ?) k6 i* s    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) and
( Y" M0 T5 V) f    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]
8 [  F$ _: Q% u2 o( D4 F. x# u! h$ G4 ^# L) [; j
  ask roads [ set pcolor white ]
2 x* h% j$ ?" `    setup-intersections
% h) I( w9 H3 [( [8 z" S, @7 m% d) G$ Z; lend9 D3 t# b! e* N1 d/ K+ J7 r- g
其中定义道路的句子,如下所示,是什么意思啊?  x/ e) E& \; r% }, B
set roads patches with
4 a5 D3 n% k2 `0 q0 i- ]' E    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) or$ W# Y& I9 C3 p1 }0 Q/ k( B0 l# W
    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]/ T* [5 p9 s) B) q
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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