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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。
, @2 i8 v  u& {/ gnetlogo自带的social science--traffic grid这一例子当中,) o  h( ^& B0 Z
globals- v6 a) H  p+ d% Q, T& \  l
[$ B& N) {% C, a5 _
  grid-x-inc               ;; the amount of patches in between two roads in the x direction6 p1 y% G+ Z) M; T/ V
  grid-y-inc               ;; the amount of patches in between two roads in the y direction
, S9 e. y6 E. w  acceleration             ;; the constant that controls how much a car speeds up or slows down by if
: y& f) ]$ e; n# @/ _                           ;; it is to accelerate or decelerate
/ ^: d! I$ f. t  phase                    ;; keeps track of the phase0 \8 e" i7 s5 c5 b+ t  X3 C0 O
  num-cars-stopped         ;; the number of cars that are stopped during a single pass thru the go procedure
6 P  h8 n3 E3 C% }# E' g3 M( t  current-light            ;; the currently selected light) |4 g/ H* E# R  {+ J. Y
, F# s* a& F% _! V" m6 d
  ;; patch agentsets
/ B" Y! ~/ B5 S  intersections ;; agentset containing the patches that are intersections) L! A1 d) z( r) `' s
  roads         ;; agentset containing the patches that are roads  C) F% q) Z! Q& ~
]  X3 ]7 Y3 ~1 v" i  h7 Y! ^

) Y$ l; z6 ~4 Xturtles-own
% v( Y& A9 y9 f; ^/ Y+ c& V8 j[7 q5 }- q2 G8 [& ?* K
  speed     ;; the speed of the turtle
# `% b9 V4 M: u  A  up-car?   ;; true if the turtle moves downwards and false if it moves to the right
0 p" E) ^- y( L8 d3 o  wait-time ;; the amount of time since the last time a turtle has moved
6 u8 I. J# `) ~8 t7 j. [. r" O, w" P]* Q2 y" c1 Z( ?: w9 m, `5 R

" ~3 L) B! j: X$ Q8 n8 j/ ~$ {patches-own& e  {" W) b3 t9 [1 m/ ?
[" P4 m; v# y/ u. }& a" t, G6 ^3 h9 {
  intersection?   ;; true if the patch is at the intersection of two roads
* i$ w/ `1 L- ?( P$ {  green-light-up? ;; true if the green light is above the intersection.  otherwise, false.
  h7 k& p& [# r* C                  ;; false for a non-intersection patches.
, V, p3 n0 O' o' z/ X  my-row          ;; the row of the intersection counting from the upper left corner of the
" Q7 g( L) Z* s/ s% W( A                  ;; world.  -1 for non-intersection patches.
6 o& A( q1 X$ y  my-column       ;; the column of the intersection counting from the upper left corner of the
  @# d, w! Y3 q0 }9 c                  ;; world.  -1 for non-intersection patches.. Q6 B7 a9 ?: @; b0 x' T. x
  my-phase        ;; the phase for the intersection.  -1 for non-intersection patches.! x% ~2 ]+ y7 p+ @
  auto?           ;; whether or not this intersection will switch automatically.
: o. b1 D# u- T                  ;; false for non-intersection patches.
4 L1 q. p; g- D$ O' e* p# t$ Z$ B]
; K* ]  ?5 o- U- M: M% `1 ^$ @0 T2 s" u
% U! t4 a3 d3 m! y3 n# L( H; ?' U% C+ X3 f  k' `4 n
;;;;;;;;;;;;;;;;;;;;;;9 v% r0 j% N, k% N" j
;; Setup Procedures ;;4 f5 K. Z' K; y$ i+ |
;;;;;;;;;;;;;;;;;;;;;;
: s7 g! e% \) _. _; \  H9 G; b2 u% K% A* I$ o" y
;; Initialize the display by giving the global and patch variables initial values." q7 O% J) ~% w
;; Create num-cars of turtles if there are enough road patches for one turtle to
; O$ @# x% E) k) h;; be created per road patch. Set up the plots.
! P, u* b1 h  l6 yto setup
2 q; E3 t9 I$ X; b, B  ca# \$ j! `. ?- S
  setup-globals
- |' @/ I6 u, D+ N3 g6 ~, W% B  w- W8 M  y+ y
  ;; First we ask the patches to draw themselves and set up a few variables
8 s+ g% A! i' D. U/ a  setup-patches
& Q& l* r; k$ S0 \1 L5 a" v  make-current one-of intersections3 l6 c# S  ?" e
  label-current
$ c" f8 T* f% b4 d3 T: z% Q4 U
. D6 M" B4 X/ Z2 E  set-default-shape turtles "car"
7 |; w5 k1 }8 b7 X- z2 G% d( n7 M* U8 N2 o  `! f% U7 {' u  Q
  if (num-cars > count roads)$ s1 s) {* K4 a: U
  [+ R% m! h8 \2 z$ I6 J6 ^6 \7 v
    user-message (word "There are too many cars for the amount of "' B3 g* [) X! E* s5 d
                       "road.  Either increase the amount of roads "
1 p+ X5 N6 b3 S/ e1 }0 H                       "by increasing the GRID-SIZE-X or "5 e+ k! o9 q2 Z, ?
                       "GRID-SIZE-Y sliders, or decrease the "# h9 ^  j' I2 l4 E$ W( b3 S
                       "number of cars by lowering the NUMBER slider.\n"
- b$ T6 H" d, {% i, I; c  O2 b7 W                       "The setup has stopped.")
1 A% ^5 ~1 a" f! F! p, r0 Y    stop" K0 c8 a3 ]3 {) O$ v7 n8 X
  ]3 j# _, P* ^' u7 v
' k7 {6 x" o* E
  ;; Now create the turtles and have each created turtle call the functions setup-cars and set-car-color
% J/ v* f* B* o  V9 I  crt num-cars" Y6 G7 _& h5 X/ H" a; q
  [
0 f( P/ B! d6 K6 z9 |    setup-cars% d! ]0 T7 i9 D4 r& ]" H3 T
    set-car-color0 `+ R* i! F2 q- E9 y
    record-data! t+ j0 I% k; @  ~6 b1 @" I$ g
  ]
+ s1 t0 ?* w7 E/ k/ H0 u. }1 n2 X* M' I
  ;; give the turtles an initial speed% r0 }/ V+ r3 }: E, K
  ask turtles [ set-car-speed ]0 m+ P) A! a* S& u7 b% R  N# R
( f. c0 f% a2 i9 X5 Y( o
  reset-ticks
9 @) ^9 i5 w: r5 wend
& a0 h' }) u4 I# Z6 d
6 [7 C* H; m( ~;; Initialize the global variables to appropriate values! t0 A+ w* y% \
to setup-globals
- f$ w8 \0 A7 M0 n" @$ _6 k; `& k  set current-light nobody ;; just for now, since there are no lights yet/ r5 r3 I" ~1 c* O8 d, U
  set phase 0' |0 u( S$ v; |
  set num-cars-stopped 0$ M& W, d9 H5 i& ?- ?0 B3 Z; P( i# ?) d1 u
  set grid-x-inc world-width / grid-size-x
4 h3 a: o! Y1 y% N/ w( w  set grid-y-inc world-height / grid-size-y  T8 E- w# M2 V

% I7 z' a. W6 m" I  ;; don't make acceleration 0.1 since we could get a rounding error and end up on a patch boundary, }, c. J. e5 U* q; b, d8 u0 a1 Q" a
  set acceleration 0.099
1 k' X; Q' @! s- I* L/ r3 w5 Jend( E, Q) ^9 J9 V( V3 f0 i

& ?- n, M9 g2 Z" r, Q* o# w, g;; Make the patches have appropriate colors, set up the roads and intersections agentsets,# n' j" C  A1 K; F( j' @7 x7 o$ T
;; and initialize the traffic lights to one setting8 T/ x3 [6 p% o9 ?! Y0 X! e
to setup-patches) o: n; Q$ f8 l) P1 ~& Y7 Z# X
  ;; initialize the patch-owned variables and color the patches to a base-color1 @0 i9 u3 P; Z& v$ u; {
  ask patches
6 J& {8 H- f& y# [  [
( [) p1 d: {. w, r, ^. P9 Y    set intersection? false$ [0 c* M4 z/ l- Y5 D" u' J6 i1 ]
    set auto? false
" E9 G, Y' D+ E8 V- n    set green-light-up? true
  s+ r* S, B* G9 @" d1 J$ p    set my-row -1$ q, F. I' O! c  v2 {# a0 d. d8 w
    set my-column -1
& I3 {9 B& [/ A' V  D  f2 m    set my-phase -1
! x1 |; e3 F4 X. {5 p( m0 k; i3 L% d    set pcolor brown + 3
( q- W; [) Z  B; W& C  C  ]& \# r' C7 j; t6 }
+ S( T: g, M% q" {2 x
  ;; initialize the global variables that hold patch agentsets8 u" j( L* I% w
  set roads patches with3 d" ^2 ?! ^8 u6 s- v
    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) or+ ]$ w" c$ `: V1 ?2 F
    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]
. i! v, e5 N, C5 I' ]+ g$ q  set intersections roads with
2 D# f+ t, s% V. y' ~* i    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) and% U. D8 R: G$ l" C+ b, Y+ P1 p
    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]
/ H: r  `1 t. z8 n# S" t& W6 y1 l  M% x, I7 S  ~
  ask roads [ set pcolor white ]  Q: k: T  K; C# v9 m. V+ r
    setup-intersections
6 O$ O9 V& a/ F6 ?5 ~end: |& t# ^9 K2 j6 @. `1 V
其中定义道路的句子,如下所示,是什么意思啊?/ |8 {0 @# S) ^- r% E
set roads patches with
# v: `* H2 h) }$ Q    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) or
9 ~8 p% \/ L* E/ Y7 p0 Y+ i    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]* B0 x  r- D4 A. L: I
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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