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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。
) X. _% l: `- j4 U/ z$ qnetlogo自带的social science--traffic grid这一例子当中,$ D/ F7 Z2 ~6 ~; v% s0 p
globals
" g$ Z, Y; C' z: W5 D[
* R5 `% C. j+ j' a  grid-x-inc               ;; the amount of patches in between two roads in the x direction
$ U2 H; x* M% P; _  grid-y-inc               ;; the amount of patches in between two roads in the y direction
; g. ^/ e5 ?, V1 ~; j3 u/ f, p/ Y  acceleration             ;; the constant that controls how much a car speeds up or slows down by if
* g/ G( B7 H0 `0 k7 j                           ;; it is to accelerate or decelerate
. Z; i6 d9 e7 h; Z' y( N  phase                    ;; keeps track of the phase
) P+ g( {5 {' O- d" K/ X  num-cars-stopped         ;; the number of cars that are stopped during a single pass thru the go procedure
9 h' R8 H9 j  E1 c4 ]5 ?; x  current-light            ;; the currently selected light
2 C0 }* R4 m$ H3 j) w4 s  X. A
8 z5 ]/ J3 \6 `# j2 `  ;; patch agentsets, r* e8 o. R4 r8 I9 B7 C
  intersections ;; agentset containing the patches that are intersections" K* [$ k2 i. ^5 B+ A+ y9 ?
  roads         ;; agentset containing the patches that are roads
& Q3 U* y) Z) \7 w+ Z]' d- F+ a3 Y2 e. C$ i! H

4 P2 r. \% o' c, H9 Jturtles-own( q+ V% \! _1 f" c( J
[. Z, X" [& A% w
  speed     ;; the speed of the turtle4 r2 w2 Q0 l) V
  up-car?   ;; true if the turtle moves downwards and false if it moves to the right8 R5 Y. C0 e8 d, W. H/ i
  wait-time ;; the amount of time since the last time a turtle has moved+ d& G' y- q' d
]8 p! U- l' P3 F! h! W

/ O* m3 y3 K$ o$ P! ~0 j9 P% Spatches-own3 G6 Y4 h/ a9 W, C; r' u
[  H# j1 C) O, D. b4 O7 L
  intersection?   ;; true if the patch is at the intersection of two roads
3 s4 g5 H3 K, @- X0 x! Q! d6 J  green-light-up? ;; true if the green light is above the intersection.  otherwise, false.
; ?  v4 C1 C7 _0 J7 n                  ;; false for a non-intersection patches.3 P6 j/ |3 C6 N4 g
  my-row          ;; the row of the intersection counting from the upper left corner of the
8 v. y* S2 ?* `0 T                  ;; world.  -1 for non-intersection patches.8 K% b5 y) m' r! A$ x: k3 u. t
  my-column       ;; the column of the intersection counting from the upper left corner of the, V: w5 x0 m2 |2 U+ i7 R
                  ;; world.  -1 for non-intersection patches.! O9 q: o& @& b' y. k
  my-phase        ;; the phase for the intersection.  -1 for non-intersection patches.- e4 R4 J- I# \5 r5 R5 t
  auto?           ;; whether or not this intersection will switch automatically.7 b" f/ @( g2 H) I9 ^" f) }+ E& K
                  ;; false for non-intersection patches.$ }. h3 \1 K* n3 A/ C
]0 x8 _: A! k5 D( k

+ o9 D6 A/ a7 l# o: e
; G$ K- x1 j# t# ?: o;;;;;;;;;;;;;;;;;;;;;;1 Z  C7 A/ \6 C4 C' e0 [4 n, T
;; Setup Procedures ;;  V6 [3 p8 a0 c
;;;;;;;;;;;;;;;;;;;;;;
$ r, V2 q$ W. x! J! T, [0 b; u% t5 `4 q2 E7 O
;; Initialize the display by giving the global and patch variables initial values.
" _4 U. {4 F$ [: j;; Create num-cars of turtles if there are enough road patches for one turtle to8 p$ v& A9 r9 L+ y: `' K
;; be created per road patch. Set up the plots.: d/ @# A" B' P
to setup
* r! {! G- I5 z9 O5 E9 b# L  ca) T9 p4 `9 Z# h- y5 Y! L
  setup-globals) v8 R3 Z" \0 Z* ^

& T$ H8 I! j, u. F2 C% d9 m* }  ;; First we ask the patches to draw themselves and set up a few variables
, N1 ^5 @2 W* L7 z7 o" x/ N! I  setup-patches4 ?* U. E0 W) z  c) V3 F4 K* ^
  make-current one-of intersections
  H- U" y. e) Y8 A4 p  label-current$ a# o6 Q$ D, H$ g. }# A7 H& {
3 c9 g) W* T; m
  set-default-shape turtles "car"+ N2 Q* s, L3 u" ^3 Y

4 Z$ \9 e3 l2 B+ q+ }  if (num-cars > count roads)* {3 r1 e- b0 u, o7 q2 Z! g
  [
$ h" Y5 H$ Q& t" w( b9 J" n5 K    user-message (word "There are too many cars for the amount of "
' Q  @: ?$ `( c  s1 f7 d                       "road.  Either increase the amount of roads "
' b% H% M& v; A; X" o) D& b' W1 t                       "by increasing the GRID-SIZE-X or "
6 J6 B4 y8 b. r                       "GRID-SIZE-Y sliders, or decrease the "
: `4 c0 G2 U+ g8 B- C                       "number of cars by lowering the NUMBER slider.\n"
+ A! W% v5 C. B                       "The setup has stopped.")! k  Z" b, m$ I9 v0 M
    stop
0 B6 `! B% l' i5 [5 [5 [% o+ }  ]
2 O9 \1 S- B. q: f% C$ @( G5 `$ S* U; g" [+ W8 V
  ;; Now create the turtles and have each created turtle call the functions setup-cars and set-car-color
! B2 E7 b$ I% x% Q; r  crt num-cars
  s9 C% m/ z$ [- Q8 A  e  [) Y. j  s9 K% g1 a2 E, j9 Z
    setup-cars' R% @  D2 {8 R6 H2 N
    set-car-color" a$ q3 i! O$ G
    record-data) W2 i* _' p- k" l6 m3 Q- Y) e
  ]
0 m5 a/ g3 i4 N3 b5 r# s2 m" i! p! Y+ M4 f$ u2 _4 W
  ;; give the turtles an initial speed1 L3 d( N0 W5 j7 g* U6 y0 q% ?
  ask turtles [ set-car-speed ]0 H( S, }: T4 h8 A2 m# n7 f9 L; F

" f$ a# V/ I  m- n! V  N/ v  reset-ticks
0 r1 @* a8 I+ c6 @( Oend
' {" s4 f4 x0 k" H5 B% z
0 N$ {9 \3 h' D0 Q6 ?;; Initialize the global variables to appropriate values! @3 q1 X& i4 r
to setup-globals
- [  D# X2 z0 _  set current-light nobody ;; just for now, since there are no lights yet
0 A0 m% Q; N9 @& o1 g) }% `$ M4 r  set phase 02 Y7 |# p3 @6 W- b$ B4 t1 N
  set num-cars-stopped 0  A$ n* W4 @0 I- X
  set grid-x-inc world-width / grid-size-x
( r& p+ }8 h1 f1 H! I; ?1 [  set grid-y-inc world-height / grid-size-y
! R8 H) U0 S7 A+ G4 ?9 z8 _  h1 m# o: f4 G
  ;; don't make acceleration 0.1 since we could get a rounding error and end up on a patch boundary0 c$ L, K8 v( k
  set acceleration 0.099* q- G; J" x* i, Z; m3 F
end
" a4 \7 D' F- H% C, M2 _. y
  a4 A0 x. {6 Q+ F;; Make the patches have appropriate colors, set up the roads and intersections agentsets,$ L1 e+ b9 h' \; E2 X, Z- e
;; and initialize the traffic lights to one setting" p& d( }) \+ y2 B) R# v$ o
to setup-patches
' o7 g! n! C' |* O" G& M1 R  ;; initialize the patch-owned variables and color the patches to a base-color
1 g$ I/ v; o2 A7 J* n, R* f  ask patches8 Z! h$ m5 H8 H" `
  [
! B* n' j4 i3 A9 f. I+ O6 [    set intersection? false
" z5 g) k( }+ c5 l    set auto? false
& b4 [0 j8 h5 {7 r% J/ A    set green-light-up? true, H5 {/ {: ~. l& `. b+ B) k
    set my-row -1/ p' W# J% F% c# H5 W2 M5 ]
    set my-column -18 A% u" Y2 v; N4 B5 h! s! Q, G
    set my-phase -1: c: W9 ]1 K- U+ H  ]
    set pcolor brown + 3
4 _, d4 T3 J7 v. S  ]+ i2 g& Z* y' y) A

: {6 V" C3 b8 w; c. ?  ;; initialize the global variables that hold patch agentsets5 D5 x* {: n# c9 Y' Q9 F' O
  set roads patches with6 R+ C  \& b4 {" y/ R* ]
    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) or/ r- x1 b" b+ v' G6 i) W
    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]/ Z. [& P) B$ t8 A7 h# Z
  set intersections roads with* R7 X! [4 e* {: D- c
    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) and
$ P' V3 x! b' Q/ E    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]' t2 W! D: k3 `2 O% f3 n

8 J- V3 ]8 `8 Y0 j) V  ask roads [ set pcolor white ]
# C/ T+ c; [" a    setup-intersections
6 w* l2 G- |' o; bend1 p3 ^2 x* s# Z6 K# J0 G
其中定义道路的句子,如下所示,是什么意思啊?3 M" L# |) n# i4 ^: v
set roads patches with
% J( O, a  e# I! v+ L    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) or3 {; _9 D+ J  V6 h/ y  @
    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]
. e, ]: R: a4 i& 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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