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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。: _6 s- O+ l5 P' k
netlogo自带的social science--traffic grid这一例子当中,
# @/ l. B0 Q; e7 lglobals
+ \1 `! r; J* m, M( z2 d[
. ^4 P( G" G0 H" A2 j: H  grid-x-inc               ;; the amount of patches in between two roads in the x direction$ n* x! _# C( [  X, r
  grid-y-inc               ;; the amount of patches in between two roads in the y direction4 [% y3 K: \5 |- R7 `6 r5 S. o- o
  acceleration             ;; the constant that controls how much a car speeds up or slows down by if
* o. M' K- v/ |& V6 l2 W9 v1 z6 m' T                           ;; it is to accelerate or decelerate
5 l1 N2 t1 m& \% e; N( R  phase                    ;; keeps track of the phase
; S7 S' p) |9 a- J, V! _2 j  num-cars-stopped         ;; the number of cars that are stopped during a single pass thru the go procedure
* R0 u8 g7 \! J( R, L: [4 m4 }  current-light            ;; the currently selected light3 [+ v/ c# x' }, ]. s2 p

2 P% n2 _5 d* u# k  ;; patch agentsets
* S+ B* l& J5 W$ s; Q0 w  intersections ;; agentset containing the patches that are intersections/ J7 J' t# _5 Z9 L
  roads         ;; agentset containing the patches that are roads
; @& k$ w; t- K( K" q4 f. q]
9 l) `  q7 B+ ^0 w' G* [( |- {4 g5 S# E' O4 T' f! v
turtles-own
" A. |6 X6 C& ?4 J0 s7 o+ t+ a) f[! q. j3 X) {5 Q0 T) _
  speed     ;; the speed of the turtle
( j" M# N1 q( I' E' M9 ?$ L$ r8 _  up-car?   ;; true if the turtle moves downwards and false if it moves to the right
' V& B0 q( N& z# ^( D. K' T4 y  wait-time ;; the amount of time since the last time a turtle has moved
# V, I/ x3 ]* ~+ \% \( ~2 W]
- J( Y& N0 b$ T+ Q: Q8 u! y. P% V" K% F+ j; r1 t; ^4 b. w3 ^9 u
patches-own4 G' p  y; n* ?2 l
[
, Q* p, j7 F; P1 E6 f. C5 P3 \: w  intersection?   ;; true if the patch is at the intersection of two roads
- q  h3 T1 C7 L5 d8 v1 _$ Y5 z  green-light-up? ;; true if the green light is above the intersection.  otherwise, false.
4 ^  g3 I2 T) F: Q( d' [                  ;; false for a non-intersection patches.) n6 s, I1 [' u6 p* ~. b" }
  my-row          ;; the row of the intersection counting from the upper left corner of the
7 i4 r! [' S1 ?$ g                  ;; world.  -1 for non-intersection patches.
' p& C- X, G7 I6 |+ v' J* }  my-column       ;; the column of the intersection counting from the upper left corner of the
" j1 N) i' W: \1 c                  ;; world.  -1 for non-intersection patches.
$ u3 Y* h7 {3 `2 I; m+ ^2 ?* C  my-phase        ;; the phase for the intersection.  -1 for non-intersection patches.  _* I  c% T8 J6 W; ~
  auto?           ;; whether or not this intersection will switch automatically.
+ M& f/ M# l  q1 f                  ;; false for non-intersection patches.
, ^5 v+ r' U; x6 F! E  w: Z* K]  y" [* w: X( Z& n" m7 h
; p# o( H' L+ s6 v; U
, W  D/ Q8 j, H- a" Q1 r
;;;;;;;;;;;;;;;;;;;;;;
& V! a/ [; D( d" G1 _0 l;; Setup Procedures ;;
( S. J1 O* g. X: K;;;;;;;;;;;;;;;;;;;;;;% q" K+ d7 }6 P* W) w  T$ [% I. P

' `9 b+ U9 h' H) h' U6 e' u7 K" I;; Initialize the display by giving the global and patch variables initial values.2 d8 h- B. [9 P% C/ q5 p# v
;; Create num-cars of turtles if there are enough road patches for one turtle to2 \- c. l/ M$ }' z! i
;; be created per road patch. Set up the plots.! e% F" N. d. s+ u2 r1 u! N! s# ?
to setup
  }& s. s6 F2 V" i$ a  ca/ C% t8 [$ A. W8 j1 T! J
  setup-globals2 Z, r9 O( ?/ v8 E
4 L& z. o7 t- h, d* m
  ;; First we ask the patches to draw themselves and set up a few variables
+ N# V: d7 v5 v3 G" U  setup-patches  D& b4 x& |9 o7 R6 Q7 V+ z
  make-current one-of intersections: }- m: j5 G# X+ z8 I* Y
  label-current
7 V9 O% w9 I8 ^, ~5 |1 \& ^. |. ~4 {  u$ F* O0 G$ e" S' A
  set-default-shape turtles "car"7 f8 w/ C4 p4 F7 \  i; h3 H

/ g; D! a: A' _  if (num-cars > count roads)
/ t' k0 \* ]: Z7 o! P# L$ v' B: i  [' `. {9 ~/ W; b; @- F* o
    user-message (word "There are too many cars for the amount of "
" {/ `/ V1 J1 a& h. n                       "road.  Either increase the amount of roads "+ L* j  `( m0 f6 o: M
                       "by increasing the GRID-SIZE-X or "( k  G) g: Z% m9 ]) m; h
                       "GRID-SIZE-Y sliders, or decrease the "
6 F8 z9 F/ x6 o& o" {                       "number of cars by lowering the NUMBER slider.\n"
  S/ ?# ]+ Q; s* @) |0 \  P7 c                       "The setup has stopped.")+ z: S7 W# n, x, F  F0 T
    stop
; V: u- U0 C8 R  ]
, u& Q3 o3 `1 P) u: h5 x( L8 t! {- u3 m" ?% L% f( B
  ;; Now create the turtles and have each created turtle call the functions setup-cars and set-car-color0 p" L6 C0 i) H, C2 I. b$ a
  crt num-cars+ {9 G: h, o' L' Z7 L
  [7 S) Y- k5 u  U6 X  }% ?$ V' s8 I
    setup-cars
7 ?3 {3 R' \% C. U    set-car-color$ e, z1 l0 m3 I2 R; ]% _$ h
    record-data! F, A$ O" E) x. @" T8 e# J& [
  ]
% N- s* J1 u2 O5 \+ O2 p  n5 j
, u" b% C) B3 T$ n  ;; give the turtles an initial speed% `! c3 H! Q" N  S, r1 Q
  ask turtles [ set-car-speed ]6 x- i1 g" S! ^$ f' ~$ n

. L) A; H' h3 K' w7 s5 h+ _& ?  reset-ticks
9 ?# n( b/ c4 m- i5 oend
$ c' v- Y6 s& l: I6 U# L5 L# Z
;; Initialize the global variables to appropriate values
6 a7 P( l* C4 e  M8 j% O1 [to setup-globals
; w: H$ Z& H+ _( Z  set current-light nobody ;; just for now, since there are no lights yet4 X* e$ U" S5 Z$ d0 O; z
  set phase 0
$ ?+ @! F  g; n8 |  set num-cars-stopped 0
+ n$ `" }1 F  ]) o  set grid-x-inc world-width / grid-size-x* p/ e! i2 B+ m2 f
  set grid-y-inc world-height / grid-size-y& X/ X( J4 a# G& m

- [+ `% `. B: d7 I  ;; don't make acceleration 0.1 since we could get a rounding error and end up on a patch boundary2 ~5 d) @4 y# K2 E6 V+ _- o7 Y
  set acceleration 0.099
; P( X4 L0 Q9 J9 a' E/ H6 cend
7 f) u" x7 L5 d/ Q+ y, U$ T- f( D
;; Make the patches have appropriate colors, set up the roads and intersections agentsets,
9 m# u$ D4 P, S;; and initialize the traffic lights to one setting% U( K  l. Z5 X' p
to setup-patches
1 D: P( \" J7 y2 k5 V- M! y1 K  ;; initialize the patch-owned variables and color the patches to a base-color  ?6 o2 a  F, [7 t
  ask patches! C" u- C# d/ L0 ?; n. h1 `) S
  [
3 ?" ]+ b8 Q0 e, O( t    set intersection? false. p0 _- _, V6 c" @# N1 U
    set auto? false0 a5 d" L' `8 e9 N; V7 D/ N1 h- f3 E- z
    set green-light-up? true; @6 l) A/ O. j; ^: N+ I2 L
    set my-row -1( A% B2 f* x0 }/ ]9 ^. @- r3 {4 q7 ~
    set my-column -1
) v+ `7 _- R$ U8 g. @, ?    set my-phase -1. `- e7 U! c7 W1 _8 o2 n: w
    set pcolor brown + 3
+ A5 s* W  R& u! z  ]% _4 |8 q5 v+ q% y4 f# y9 ~; N

% \8 v/ M+ N8 R& A2 A. [  ;; initialize the global variables that hold patch agentsets, A$ p9 a) z+ C6 i' V, m
  set roads patches with
7 K! S" O* P* y    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) or; p$ b1 n* k% g" z* Q
    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]
4 G3 X+ i7 n. l1 Q9 K+ s  set intersections roads with' A% L6 Q9 {% Q
    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) and6 i" t+ d. Z. U4 L
    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]+ s3 [$ l9 _4 k0 N, o% T6 [; a

8 ?2 ~, }; |" j2 J% g/ o2 T4 b9 e  ask roads [ set pcolor white ]8 |  {& \9 q  N/ T, w
    setup-intersections
( t3 h7 f4 q9 ~- F" y7 ?end
/ X) v* X6 g, t* ?0 c  ~其中定义道路的句子,如下所示,是什么意思啊?! e# r3 k6 R' X
set roads patches with7 G- Q7 G! |% @& U4 k
    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) or; @7 q5 ~: [' E) o+ G/ D- G
    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]6 N1 N" D) t) B" 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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