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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。
+ A# u; P( ]% u7 Y/ z: u+ ^netlogo自带的social science--traffic grid这一例子当中,
) Y9 C& r, s7 h5 ]1 B  ~8 }0 F0 gglobals
. U7 I6 O" l$ K; }[
4 P! V( z5 y& [, ?' H/ j  grid-x-inc               ;; the amount of patches in between two roads in the x direction, H8 ?' F( Z( _6 d9 [1 v; V
  grid-y-inc               ;; the amount of patches in between two roads in the y direction
8 k" G- j% q, z$ F2 @/ l' y7 L  acceleration             ;; the constant that controls how much a car speeds up or slows down by if  w) \: B% N0 P7 e; K
                           ;; it is to accelerate or decelerate
, }7 v; ^0 O3 z  y) M2 T+ x  phase                    ;; keeps track of the phase
9 I" j" m  i6 _/ b2 i  num-cars-stopped         ;; the number of cars that are stopped during a single pass thru the go procedure
! n+ b0 c, M8 w! m! D1 S; {  current-light            ;; the currently selected light" h0 _  }: s+ N2 r: p. B

& J( C& j, a% I2 d' p% x  ;; patch agentsets2 `- [/ g2 K0 m/ s* j; H' t* _
  intersections ;; agentset containing the patches that are intersections
' E0 q* q3 }" q' }  roads         ;; agentset containing the patches that are roads
+ ]* Z! H5 K# ^9 G]
1 d% |7 D6 S* ]- n3 ?- t0 O. A% X# [' Z' R' b! s4 W
turtles-own' F+ E1 D5 J: v2 T$ [( O# l7 ~
[
4 f3 r  C3 X) k4 A3 ?" Q  speed     ;; the speed of the turtle$ ?9 E/ M$ \/ x+ f7 P
  up-car?   ;; true if the turtle moves downwards and false if it moves to the right& U' x: ^7 l* T: |
  wait-time ;; the amount of time since the last time a turtle has moved
8 ?+ F8 @& Q0 f0 P! z4 ~$ W5 \]
# O0 o5 C( M7 t: {
2 Q' n/ S4 c5 P: x4 v5 G+ n7 ~patches-own( k! u% ]6 c! k
[  i7 N4 K& B  Z5 O* E+ m& P" x
  intersection?   ;; true if the patch is at the intersection of two roads% C' A4 H4 C' m7 G) B& m  l/ Y
  green-light-up? ;; true if the green light is above the intersection.  otherwise, false.
) ^2 L2 K) w' @2 d% A# G/ d: S( [                  ;; false for a non-intersection patches.
  V# z4 b* x. S4 @7 V  my-row          ;; the row of the intersection counting from the upper left corner of the
8 o2 O( v( u' u% D& S5 f+ d2 l                  ;; world.  -1 for non-intersection patches.% @  x7 l9 I, i1 M5 u2 }8 d2 \
  my-column       ;; the column of the intersection counting from the upper left corner of the( {' E  w  X3 E& c* b7 n7 S3 n
                  ;; world.  -1 for non-intersection patches.
; [7 W, W, N9 w' K! m1 g  my-phase        ;; the phase for the intersection.  -1 for non-intersection patches.5 [2 s7 M* q* y
  auto?           ;; whether or not this intersection will switch automatically.
* q/ @7 i1 W9 t" C" v4 c: ]* Q% y                  ;; false for non-intersection patches.$ g1 n0 A/ k: U) z7 a1 [7 O9 M
]4 T" ]( O% |2 G( s& {) D/ V2 f

8 M1 L5 Q+ f  I) Y+ k
3 C2 A' q7 ?+ [& E4 C1 F! _* _. u;;;;;;;;;;;;;;;;;;;;;;
( i0 o1 n- U0 |' S;; Setup Procedures ;;
4 {# m9 [; N& N) \( r+ O0 `4 s6 v;;;;;;;;;;;;;;;;;;;;;;
% s3 K  l. P6 l! A
0 A: Y; J+ Z+ S( p;; Initialize the display by giving the global and patch variables initial values.
0 C! B( j- E, C- _- N/ W;; Create num-cars of turtles if there are enough road patches for one turtle to
! R) d5 c. H7 {9 ]3 h;; be created per road patch. Set up the plots.
& b, T8 Z$ p/ R. |  H+ m, Fto setup
  v2 D* G7 j$ X4 K  R. g  ca
# h, ^* I' Q/ c( N/ ~0 q  setup-globals+ Z; r. ~# ^- |% P

6 A) H) `  ^( d  ;; First we ask the patches to draw themselves and set up a few variables2 e% {+ m& A4 g+ Q, }
  setup-patches2 B5 c+ ?( G. v& o  _! w3 m
  make-current one-of intersections( q8 ?4 K& y7 \! i% W. Z
  label-current9 ~$ D! \8 P7 _* X  X  Y5 o
7 S3 |! l' j7 q* z/ f! n% F2 I
  set-default-shape turtles "car"
! n% x3 ~. a# s
& t. W6 e. v6 c2 v" P) w  if (num-cars > count roads)# H  }. g  V' U5 g% o4 @- d
  [
2 V2 }% q% @( c0 S2 g9 W7 }" N/ v    user-message (word "There are too many cars for the amount of "& t7 P' M) h+ W9 z/ R
                       "road.  Either increase the amount of roads ". O6 j( \2 h% |' J- x' ?: M9 }
                       "by increasing the GRID-SIZE-X or "
8 B% c5 P4 @- a9 n$ O3 e* s  K                       "GRID-SIZE-Y sliders, or decrease the "5 l0 u# W3 n+ l8 M1 Q
                       "number of cars by lowering the NUMBER slider.\n"0 {! P8 D( Y) r2 u* |& R
                       "The setup has stopped.")
$ s4 j* L! {4 g/ Q1 j% V    stop
& R* M6 n3 T" w5 w& t% t  ]/ [6 e4 N/ N7 I( ~" }
' k3 d( a0 \  K+ Q3 u9 e; O. b2 k4 \( N
  ;; Now create the turtles and have each created turtle call the functions setup-cars and set-car-color! W% \0 d5 b  B* t" T' h
  crt num-cars) z* T$ G  Q4 @  b  K6 L
  [& B3 t, N; K3 R, t' m% K! ~( v
    setup-cars
7 Z# u  S. `. U9 {1 e    set-car-color
; o: ^9 q( k; M8 s4 R8 e2 b% K    record-data
- G& W! A+ u6 S: c  }. f% E  ]
- V/ h+ x7 [' V" t! b  }0 ~7 Z* l! n1 P# O6 [
  ;; give the turtles an initial speed
+ w$ z9 ^- C5 U. O2 Q  F  ask turtles [ set-car-speed ]0 e  U$ h, m% A$ u( }! `- ~. P% c

" j) u: o! d0 q% x7 d: U! D* {* K7 c  reset-ticks
# G0 h7 ?& @( z' S3 M3 W" J: Oend
. o! i- r8 x/ v, K* Y3 Q5 u
" i' U: D( ]. P' ]; l% [- ^( y- N% d;; Initialize the global variables to appropriate values, |  @  L  u' L( i
to setup-globals5 J, J+ L' L7 V/ j3 A# X! J
  set current-light nobody ;; just for now, since there are no lights yet
0 k' |: `& L0 k7 a  set phase 0
1 E* o/ l6 _& \/ y, U! \  set num-cars-stopped 0  ^9 X3 o# `7 v& n
  set grid-x-inc world-width / grid-size-x, L  l+ i  t; k& B/ ?& u
  set grid-y-inc world-height / grid-size-y
, H& Q# P  g9 `6 c; n3 T7 i
  d# b) u( Y# ~+ R  ;; don't make acceleration 0.1 since we could get a rounding error and end up on a patch boundary8 \7 c& o9 W3 p1 i1 L$ Y( {
  set acceleration 0.099
, Q  w- {9 o# h8 P9 Mend6 g- o; Q4 t  ]$ \

  U6 G( G4 v" ?;; Make the patches have appropriate colors, set up the roads and intersections agentsets,
. {- m6 s/ b* m# Z. z;; and initialize the traffic lights to one setting
. Q7 S; l0 o, t6 Mto setup-patches
5 g! {1 ^" K9 O$ L- ^  ;; initialize the patch-owned variables and color the patches to a base-color
- E9 \. d) C2 }2 G" i  ask patches# a( H3 o. V+ x% A( z! l
  [
4 J  n. j6 u( ?4 ]6 W    set intersection? false9 H) S9 g8 v& Y6 E4 k: b
    set auto? false
$ g* B2 b1 G" ~  K& ?    set green-light-up? true
( N9 u9 c) I1 o- N    set my-row -1! h* ^. G1 j% C* o$ B, L% M1 w
    set my-column -1; p* q& k4 ^: b
    set my-phase -1- \7 Z7 F4 t. u& r' T
    set pcolor brown + 3
/ y$ s; L6 K0 Q7 \; e! S  ]6 \1 K/ ^" v( D7 t9 z9 R
8 z: O3 w2 T' j0 T! ~9 q  r
  ;; initialize the global variables that hold patch agentsets( {3 w8 `$ }6 `! r0 w) V- U+ _& v
  set roads patches with  O+ f, d/ c1 [
    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) or% X& ^9 V6 r* x2 J8 C
    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]
% r; |* A. y6 F  set intersections roads with# ]1 O+ L1 H) x. T9 I  n& d
    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) and
1 z8 F8 a+ a; X3 C9 A8 T1 T    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]: Q' w. m8 R! |( K, E$ K
  Z  \0 f! q7 g% q0 T
  ask roads [ set pcolor white ]
: q  P& o; u6 M" e8 }    setup-intersections; n8 J* a# L) u# |. J! m2 J
end6 I/ y6 M  d4 D" x
其中定义道路的句子,如下所示,是什么意思啊?  W, g; M0 @% h2 M9 Q
set roads patches with
% Q3 A' l. P! p    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) or/ K2 M, F" z2 i5 E) q3 T4 i) v! k, L
    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]
3 u$ g* [( ]" z$ l- q" d8 G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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