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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。9 r( X" F: |2 V, Q3 {1 }4 Y
netlogo自带的social science--traffic grid这一例子当中,
: ~# [" }7 ?8 P# `# d+ ?globals
/ E9 L$ _% U/ ^% y( a[
1 K3 y* I3 {# \- k+ z- u  grid-x-inc               ;; the amount of patches in between two roads in the x direction2 y, n6 j+ F6 M; t4 S3 i) c
  grid-y-inc               ;; the amount of patches in between two roads in the y direction- Y+ w# c7 l0 o1 O$ f+ h6 R
  acceleration             ;; the constant that controls how much a car speeds up or slows down by if
5 T6 x" i* r, z, d                           ;; it is to accelerate or decelerate( S6 B& W8 X7 u0 @9 v. }" i
  phase                    ;; keeps track of the phase4 Q" h" J# A3 W* H: G8 c
  num-cars-stopped         ;; the number of cars that are stopped during a single pass thru the go procedure, [4 K( z/ i; T' ~
  current-light            ;; the currently selected light8 u7 p: u0 x8 `# t
% v9 G/ {. U5 W) I# @7 f
  ;; patch agentsets! r( p: n% `1 R  W' s8 U+ ^
  intersections ;; agentset containing the patches that are intersections! B% z9 ]! ~& o: g" l
  roads         ;; agentset containing the patches that are roads9 `7 G+ T$ `6 v3 A4 V) i
]
" Z( i4 g7 A' L/ U' c& L2 a, m+ M, h3 m
turtles-own& N3 v* Z. ]9 I
[
  }3 W" m5 R1 S+ {& c% U  speed     ;; the speed of the turtle
* g' j# v' W! b4 i# f. u  up-car?   ;; true if the turtle moves downwards and false if it moves to the right
( V+ n( W+ ]0 K& D# {7 c* G/ S# J3 i  wait-time ;; the amount of time since the last time a turtle has moved
1 h) ~% O5 d) `]& p( c7 z8 Z1 ^  V' ?
7 j- r2 V) X1 _* h
patches-own
/ a" N* \' I( j4 E; L0 x[/ v% B1 m: L0 _# i" \- ~& i
  intersection?   ;; true if the patch is at the intersection of two roads4 R4 u- F' q. G. t' f; f
  green-light-up? ;; true if the green light is above the intersection.  otherwise, false.
) C; n' j4 h/ ?$ Q                  ;; false for a non-intersection patches./ Z2 t$ k; n# G# S6 Y7 X
  my-row          ;; the row of the intersection counting from the upper left corner of the
- V( [# F- d% T1 h7 J( f! F) [& \                  ;; world.  -1 for non-intersection patches.% [9 {3 Z# }2 J
  my-column       ;; the column of the intersection counting from the upper left corner of the
8 q+ ]" y4 }" t' C                  ;; world.  -1 for non-intersection patches.
( P: \; B: y, v1 S- V' Y5 F  my-phase        ;; the phase for the intersection.  -1 for non-intersection patches.3 {9 g! N7 r9 m% |# m% o- h& i
  auto?           ;; whether or not this intersection will switch automatically.# c: ^4 ^$ g6 Q& x0 e9 z" {2 W
                  ;; false for non-intersection patches.
, j8 [0 [' B. N7 V0 z]) l; A% V6 |* L+ T' E% l( E
8 r) _' o: ]/ {
5 a# F5 p! Z: Z7 v0 ^3 |
;;;;;;;;;;;;;;;;;;;;;;+ F6 u$ a" y- C" z# S$ m
;; Setup Procedures ;;
0 }( f& ~. P" u2 L& w7 O;;;;;;;;;;;;;;;;;;;;;;
* X& h* [  \1 x5 v1 C) ]
% o' _: o- w% K2 O;; Initialize the display by giving the global and patch variables initial values., Z; @8 ^" B1 b1 D4 ^; U9 c/ ]
;; Create num-cars of turtles if there are enough road patches for one turtle to* |# X: n8 s1 i; s( f+ a* B6 a% P
;; be created per road patch. Set up the plots.
7 d# A( d7 g& Oto setup
+ L9 i. W" B5 X  ca6 L9 m7 [  ?6 ]" K3 Z- d
  setup-globals
$ }6 U! e3 }1 D( T, f& p5 J4 `7 Y
  ;; First we ask the patches to draw themselves and set up a few variables
) O3 j8 A7 k5 R: X2 \3 {  setup-patches
$ p( b$ _2 T1 i# `  make-current one-of intersections
: \: C/ T$ ]: R* j4 H  label-current
/ g# f! _& p9 ~$ H1 {6 E
# c( @/ \1 t4 {  w  set-default-shape turtles "car"% L/ k  d6 w1 ^) b4 j( l

# ?$ J* O& F: h& T* M  if (num-cars > count roads)$ u( v4 g4 _+ u5 j, h2 t2 a
  [: G- p4 B# y( |2 F4 ~
    user-message (word "There are too many cars for the amount of "9 ~: `2 D2 F8 ^# X
                       "road.  Either increase the amount of roads "
7 e, l5 l, U: M- S6 ~                       "by increasing the GRID-SIZE-X or "% s* A; w0 t( p9 A1 H
                       "GRID-SIZE-Y sliders, or decrease the "# z4 Q# }& F! i5 Q8 ~" R
                       "number of cars by lowering the NUMBER slider.\n"5 n# J: W9 E9 u- h- B7 a
                       "The setup has stopped.")
: z* [% ^3 F$ X4 w; m; C9 C4 Q    stop
: ]# N1 F& x+ U& x) w# v% X  ]
* v. E  ]# Z. ~! _5 p8 F% v) V2 D4 N
7 }( n+ P" U, ~  ;; Now create the turtles and have each created turtle call the functions setup-cars and set-car-color
8 q$ r6 X" t. e' F  crt num-cars
$ @, l8 ]* Q2 z" y2 ]0 x  [7 h1 F( [) @2 A! J" j, O$ g' ~' y% O
    setup-cars
  l% M" v% j& M* Z6 k( j. Z$ X    set-car-color. T2 \9 v  `1 i: o- w6 _8 P" o
    record-data
* G; {9 p+ E2 i  ]4 v' F8 S: L% S1 l- Z9 M

& P0 Y/ q- Y1 a# m' \6 t  ;; give the turtles an initial speed
# f. k6 a. p( _0 w6 {/ d$ G; I  ask turtles [ set-car-speed ]
! X5 C( {  k  ~% N0 ^% p- A. B
1 ~! s( l( j$ `0 p  reset-ticks
, z' k) q% G: b/ X; F7 x# a5 gend
" a- V. {' U1 D$ e# P- N6 M& Z4 @  t
;; Initialize the global variables to appropriate values; H  ^) d: `2 x' G7 Q9 C
to setup-globals3 X; i) Y0 H/ J7 _2 U
  set current-light nobody ;; just for now, since there are no lights yet
2 u2 \/ e% p  R# W5 h  set phase 0
1 i, y5 _( [' R* r9 N! k* v  set num-cars-stopped 0
' u8 C2 Q/ E5 T# t0 R; L7 M  set grid-x-inc world-width / grid-size-x5 m& m3 `: c; @
  set grid-y-inc world-height / grid-size-y
' R! w( O* }8 r: q# C/ R3 c0 k9 t9 d% F- u6 C
  ;; don't make acceleration 0.1 since we could get a rounding error and end up on a patch boundary
7 K# `1 t& x4 C# f( u, G  set acceleration 0.099
4 A$ p& c0 L" @3 w7 I+ Cend: z4 Y0 x2 l, V% F1 G
  p' r0 I  T" p- W
;; Make the patches have appropriate colors, set up the roads and intersections agentsets,
4 w$ j& p) |$ a! b;; and initialize the traffic lights to one setting; b5 C" c, F! V$ ]
to setup-patches
4 k) o9 \6 d5 l* L' W4 F2 W& _  ;; initialize the patch-owned variables and color the patches to a base-color
5 P0 t4 h5 W" D6 f$ x  ask patches
* }, e. M4 I6 q2 t6 ]/ ~0 U  [. v- x9 @" C8 {" a. O
    set intersection? false. `0 ]! f; \: D3 e+ V
    set auto? false9 j; h- Z0 E+ {3 L/ v* f+ }) f
    set green-light-up? true7 `$ K1 t( a# `( Y; n
    set my-row -1( b) P$ D' o2 h, J* {4 e
    set my-column -1  ^" S# B$ N5 U; O2 t3 X; t5 e
    set my-phase -18 o) A% X- s2 [
    set pcolor brown + 32 R" c- s8 R& d$ h
  ]  K% P: b4 S* u8 {  |/ J# Z% S

6 i2 r% ]9 @+ V6 O  ;; initialize the global variables that hold patch agentsets% f) {9 C3 D* q% a
  set roads patches with) o  h0 q% p5 s. h# n2 p
    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) or
& F/ H9 G' k/ ~# E0 t5 A; O    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]
5 [$ u) ^4 F. [  set intersections roads with) y  H0 |) q8 T" o
    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) and+ P1 @4 P7 K9 t- j
    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]: j2 R9 T% y& t# q$ r8 w
! z2 U% J$ A: ~" S2 l/ h- y- h
  ask roads [ set pcolor white ]; r' O" x/ \  U5 ]
    setup-intersections
7 \% A+ X7 E7 l5 {end1 v! u1 o3 D' b( \( C4 R# D* U
其中定义道路的句子,如下所示,是什么意思啊?
0 B8 S5 Y; C6 j# N! I& L. Z set roads patches with8 H' R& `5 t- d9 Q- R3 W
    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) or
- I& h( e  X, Q! ^" W5 ^    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]
& w% g8 _6 ~, w+ F8 V; K6 E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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