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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 e4 r" ]0 Znetlogo自带的social science--traffic grid这一例子当中,
( D& @1 B/ R$ s7 \5 C1 |globals$ D" `! [* y- @0 q- q4 \7 v  e1 y
[
: A! S  F9 f# T( M1 Z. _  grid-x-inc               ;; the amount of patches in between two roads in the x direction
: G% d# Z7 N  r1 l1 r- O  grid-y-inc               ;; the amount of patches in between two roads in the y direction
+ n3 r  f' I3 T; c7 a! ^! T  acceleration             ;; the constant that controls how much a car speeds up or slows down by if
2 G/ s  d; C% r  _3 x) j! ]. V                           ;; it is to accelerate or decelerate% n. F" w" F- e6 N, E7 Y% R' \0 F
  phase                    ;; keeps track of the phase
/ G3 H- _8 S  Q" A/ L) A  num-cars-stopped         ;; the number of cars that are stopped during a single pass thru the go procedure
3 S% {" _3 W* T: L3 |: M, H  current-light            ;; the currently selected light, \$ Y) F4 p2 n/ A. z  B; r; q
0 k, |, R! ]* O% s8 ~' |
  ;; patch agentsets/ P2 O) @% `4 K! B+ I, [2 H
  intersections ;; agentset containing the patches that are intersections
  [0 ~  N; Y) a4 a  roads         ;; agentset containing the patches that are roads: l! j% R+ E* g/ V6 q& b
]
- a0 y; A) r2 r, I; s, ?( _
0 c/ K, A- |9 \: ?turtles-own
* @& I! n4 D5 z2 W6 s[
2 {. U! B7 d  |: @- l  speed     ;; the speed of the turtle# ^# Q4 x+ ], H& e
  up-car?   ;; true if the turtle moves downwards and false if it moves to the right1 [+ p- H9 o/ D
  wait-time ;; the amount of time since the last time a turtle has moved
) |/ ]! R+ n' C- u/ |6 Z6 J]
2 n% m! T: b; l* Z' E- }3 e0 X; U3 {5 @# K5 W
patches-own
* c5 v& p; R. c0 H* [, j( X: {[8 y3 ?4 a% i/ K9 ]
  intersection?   ;; true if the patch is at the intersection of two roads5 m4 x% K5 c: m. u. i6 @
  green-light-up? ;; true if the green light is above the intersection.  otherwise, false.
4 q2 b- \* v# y# \                  ;; false for a non-intersection patches.
8 w( J4 d) K) w, v  my-row          ;; the row of the intersection counting from the upper left corner of the
. y$ k) @5 S. M. R                  ;; world.  -1 for non-intersection patches.$ K2 k2 ?5 T( c8 H7 q+ ?
  my-column       ;; the column of the intersection counting from the upper left corner of the
! j0 J: {' Y* f6 F' U' l8 r                  ;; world.  -1 for non-intersection patches.$ M9 |! L2 `6 q6 K2 V
  my-phase        ;; the phase for the intersection.  -1 for non-intersection patches.  [* k6 @- I$ Y: G- {( w7 }4 b, Z
  auto?           ;; whether or not this intersection will switch automatically.$ }! G! \+ t8 s
                  ;; false for non-intersection patches.2 l' Z3 Q( [" {3 p: b7 c  a
]% b2 e4 \& n3 ?7 F/ ]" \

, l- x  y" v, F8 ?/ E1 ^; ^6 }
* u1 \- d. p/ d9 e;;;;;;;;;;;;;;;;;;;;;;- i& B: E6 r% H' c
;; Setup Procedures ;;! v$ t7 ~0 t% G5 ^2 ~) l) k/ o
;;;;;;;;;;;;;;;;;;;;;;3 J) w  f. a) s
; I* W/ u& n" ?2 y1 ~: ~6 H" U: _
;; Initialize the display by giving the global and patch variables initial values.! \+ o$ D2 ]- }# l. ?0 N) H+ w* [
;; Create num-cars of turtles if there are enough road patches for one turtle to2 i, i1 W* Y. t7 b7 M* ~
;; be created per road patch. Set up the plots.
1 |( M, ]- V. I( Pto setup
; G+ ~5 b( o, j& P* ?2 R  ca
# G* V/ C& h& |4 o8 \. K( [  setup-globals5 j, I3 D7 v; @% O; h

# m4 g) Q$ \8 T  O7 O) w4 d  ;; First we ask the patches to draw themselves and set up a few variables+ f# L; @; y$ N4 ~5 ?5 q  v# Y
  setup-patches- p4 q( F5 N6 O
  make-current one-of intersections
- j5 A% A% x. Y" C8 R  a  label-current: K' T9 {6 F8 ?; @1 x5 C6 \+ f  x

5 i: Y9 `' T# k: x% g% o  set-default-shape turtles "car"
0 l2 ]& P1 r  D  `/ O" |' {/ m; p- j6 W: v: v- d8 L( D& v
  if (num-cars > count roads)1 r# ]2 {& f/ Y) P) P  c
  [
; H8 ~) Z9 S4 p" |9 q    user-message (word "There are too many cars for the amount of "( E9 y5 e% i2 N* Y
                       "road.  Either increase the amount of roads "3 V2 w' ~, V7 o, @
                       "by increasing the GRID-SIZE-X or "9 Z* v: p3 i2 g: J' B' G+ T
                       "GRID-SIZE-Y sliders, or decrease the "' H2 r& H$ P6 p
                       "number of cars by lowering the NUMBER slider.\n"' o' `4 a; t+ D0 e- w+ M
                       "The setup has stopped.")1 {: T( h& S1 V( c  W& n
    stop* c3 u  I/ H! ?9 f. x5 R
  ]" P  \) E; e. u; Q0 S2 S2 |

( q! e8 I; F" }  ;; Now create the turtles and have each created turtle call the functions setup-cars and set-car-color0 ], w. j0 n- \! S/ k+ G  t4 H: s) ?
  crt num-cars+ c5 ?/ z7 `" E8 l
  [9 b+ I; @3 D/ G
    setup-cars
' s" e! ~3 k8 P( Q. e) W; `5 F8 t    set-car-color7 c* q! n. f$ ]
    record-data
8 I) v$ D9 @% P+ F  ]/ w. p$ w, c7 w( }% Q' l& @, k
# K& W+ R/ f9 l9 k$ Q! T
  ;; give the turtles an initial speed3 y, E0 L& s# {: ~. J, y
  ask turtles [ set-car-speed ]+ G) ~7 F) [/ M# Y8 U2 U
' b7 l. X6 J6 G! E
  reset-ticks1 h; u# a7 N: Q/ v
end
% Q* G  u! {& Q% ?, k' w) ^4 v
# [+ `" P% S! t% O0 t; l4 q  C;; Initialize the global variables to appropriate values2 d; k& D3 V/ u. K' x8 c: @6 e: w# l
to setup-globals$ Z6 u. L6 L; f; S3 b1 r& z
  set current-light nobody ;; just for now, since there are no lights yet% L0 f8 G& \# R% G" _
  set phase 0
$ a' L  E' ]8 N5 @+ Q8 [  set num-cars-stopped 0
0 }+ C9 E2 x" |& H  j3 B8 h" S  set grid-x-inc world-width / grid-size-x
9 c" x- j% k) D6 k& J( ^/ K% @  set grid-y-inc world-height / grid-size-y
' {% Z4 q7 N9 X) F6 q5 K6 B" v5 u/ E- u. d2 E
  ;; don't make acceleration 0.1 since we could get a rounding error and end up on a patch boundary
$ V6 k4 C% R7 w; p  set acceleration 0.0999 c' p- E  j1 @$ ]% a0 S2 d8 z0 a, ]
end4 t! Y9 d# X6 ^

/ J. R. F1 _$ A! d+ G;; Make the patches have appropriate colors, set up the roads and intersections agentsets,
7 r. Y8 B1 l& {, R2 S;; and initialize the traffic lights to one setting
# ?' c% m$ _# [3 Q4 N1 v* r- Q/ B1 ito setup-patches, p2 @( r  h% C
  ;; initialize the patch-owned variables and color the patches to a base-color4 ~0 T/ \' O0 S0 N: d4 C
  ask patches; d3 m8 Q5 P* D) ^" l! v4 @
  [
' d% b2 W* |5 [& a# j    set intersection? false
4 m* [1 z- i4 _* X& i3 D# E    set auto? false, A. k$ ?9 ]* {% W1 {' n$ Q3 i5 A
    set green-light-up? true+ i) G' X% p" p' }# \0 O: J
    set my-row -1' z* j) U* X; y3 i; s2 P8 ~6 f
    set my-column -1
& r6 J& t) q& M# I+ {% Y; V    set my-phase -19 z' R, g  y% W! p7 N6 g
    set pcolor brown + 3
) ]9 ~' V8 a! E  ]7 k, X, ?; n5 ~7 a$ ?' @! k; d
! V* ^+ P9 K6 Q+ _1 O7 k9 I4 A
  ;; initialize the global variables that hold patch agentsets
$ u  T4 f8 k5 [& {( {  set roads patches with
+ N+ i( f1 f& r, o& W    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) or
, l4 X- T, ^6 F. b    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]
& h* I/ F1 E/ V4 c5 M$ a0 I+ [  set intersections roads with
# S9 S* ^# }" w1 h8 \) c, {    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) and- n" G2 T+ v% u$ [$ K
    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]0 N' A' {2 }) l% S  Y
8 P4 n- ]' Y; y9 f& g  m
  ask roads [ set pcolor white ]+ l+ p& ]0 W6 b  F9 v3 O
    setup-intersections
6 ?) a7 M$ B+ [* ]* x5 x$ `end: {) M" l' e! `' z1 V( r& |
其中定义道路的句子,如下所示,是什么意思啊?
" K# ]3 c* d& z* R  @ set roads patches with
) Z0 m/ n: k! c$ X    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) or
# m* V! Z$ I  O& _+ z    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]! E9 k" o4 K: p/ g3 x
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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