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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。! }* y  O' u8 f9 v
netlogo自带的social science--traffic grid这一例子当中,$ \/ p( [5 {! H5 V4 s0 |! t
globals
! K8 X; @9 w6 F[1 \6 Y3 \- w! w% r/ @4 R" M$ P
  grid-x-inc               ;; the amount of patches in between two roads in the x direction# r. d  {9 k# h. p
  grid-y-inc               ;; the amount of patches in between two roads in the y direction
2 ~+ {  H6 o0 }- U9 ~; ~  acceleration             ;; the constant that controls how much a car speeds up or slows down by if, @: o' v/ i* v  k# `( L+ u0 S; S% \
                           ;; it is to accelerate or decelerate
5 C# z) @- u+ f1 q3 v  phase                    ;; keeps track of the phase/ y! a" l6 q( S
  num-cars-stopped         ;; the number of cars that are stopped during a single pass thru the go procedure8 Z5 n6 F# z, ~. {' ^7 s
  current-light            ;; the currently selected light+ O/ o3 P6 s$ w- K! V! `

) b3 n% k+ @: h. H" V  ;; patch agentsets
; q$ |8 I  \2 ^2 W3 C( X! C5 k  intersections ;; agentset containing the patches that are intersections+ J$ n) s% |7 K# W4 i
  roads         ;; agentset containing the patches that are roads+ B9 e2 U; d/ f9 s3 u
]' q. l0 T. ?' g. H+ t3 m9 l
  K; a; R* Y% h. z( F, J
turtles-own
4 ?; {- X( J7 Y$ h4 i- ?9 c2 _[( l+ y# r' H8 f+ f1 y! F
  speed     ;; the speed of the turtle
* n! g5 H+ f  }  up-car?   ;; true if the turtle moves downwards and false if it moves to the right
/ t& T. _/ o$ Y( M. u, w  wait-time ;; the amount of time since the last time a turtle has moved
. S1 M. N/ v0 P]
3 M- |! p% g% y" l$ o4 s% ~8 s% L
6 |- V. h2 K; \patches-own
+ P% D2 T: ^2 o- W5 ~6 Q+ l9 ^& a[5 S/ B$ N+ S8 u. x( a7 ^
  intersection?   ;; true if the patch is at the intersection of two roads
9 e3 G1 i3 J/ y/ ]  green-light-up? ;; true if the green light is above the intersection.  otherwise, false.
" k/ U- y# |7 z& a8 d; Z; E8 L5 J6 }  \                  ;; false for a non-intersection patches.
/ q2 Q$ [6 p, _. W% n5 ~% A9 U$ S  my-row          ;; the row of the intersection counting from the upper left corner of the  x' ]! E$ |1 }( ]% N- _! e
                  ;; world.  -1 for non-intersection patches.0 X" [4 D! y, X( P3 j
  my-column       ;; the column of the intersection counting from the upper left corner of the1 ]1 o( _" k/ `. @( P0 s
                  ;; world.  -1 for non-intersection patches." d9 f* l7 R( G4 c1 Y* J2 g
  my-phase        ;; the phase for the intersection.  -1 for non-intersection patches.
: L9 s5 m) O. x3 L% f  auto?           ;; whether or not this intersection will switch automatically.
! K2 ]3 ]' o: r: u                  ;; false for non-intersection patches.
/ K& \$ X1 f9 ~]& x6 ]* v% K- \  {
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2 t/ H- p; X- `; v6 G) m, w
;;;;;;;;;;;;;;;;;;;;;;' G8 Q% ~7 {, c% z! f! O! A0 i, D
;; Setup Procedures ;;  w; j# ~$ N7 n3 w* v
;;;;;;;;;;;;;;;;;;;;;;
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$ U$ I1 P2 r( ^6 {5 ]4 C- O( };; Initialize the display by giving the global and patch variables initial values.
6 p' x" m" a/ N$ G6 W* y;; Create num-cars of turtles if there are enough road patches for one turtle to3 F6 y/ l  r+ [7 P9 W
;; be created per road patch. Set up the plots.7 \8 i- x7 ~  g, j* o
to setup
# a1 Y1 x* q, I& [! `  ca0 R3 R. K5 w9 f9 C+ r
  setup-globals1 E* W) u! X9 `: O" Q. c

( m: C" f# x! M) K$ L' F  ;; First we ask the patches to draw themselves and set up a few variables
! ~; k( \( m/ A* _  setup-patches8 X7 m! B, F/ w1 V4 d
  make-current one-of intersections
/ z9 j; \. y8 N  label-current
! _1 [2 @) ?( d( Y+ S/ n& f6 R6 z' T, |
  set-default-shape turtles "car"  j0 g  w) I: l8 w; u* e1 a
6 S. g- L0 o9 ?; t5 Z
  if (num-cars > count roads); d7 t, ~2 R5 B9 ?( N3 N0 K
  [
7 \- c2 i$ G. K2 C( D) n1 L( q    user-message (word "There are too many cars for the amount of "1 m3 R7 G) y% E+ U0 V' l
                       "road.  Either increase the amount of roads "
1 A- R" e* q; H, S                       "by increasing the GRID-SIZE-X or "- Z3 |5 o; J$ a
                       "GRID-SIZE-Y sliders, or decrease the ": w- z# U' `1 |3 ]2 `+ B& N3 s# z
                       "number of cars by lowering the NUMBER slider.\n"
# n$ V4 S0 N, ^0 [- h                       "The setup has stopped.")4 W& v! n6 G6 c+ m! p
    stop8 b1 @8 K  x4 D: s9 J9 o- \
  ]2 N, |$ }2 {! j3 G+ L. n

; O3 `; W* J) ]! t0 z6 S' u5 t, ^. o  ;; Now create the turtles and have each created turtle call the functions setup-cars and set-car-color9 a0 y% A% B/ S& |7 l
  crt num-cars
& `( B. |0 ]1 j3 i- u6 p  [
. k, {+ H$ `- Z# ~    setup-cars
8 k" {2 K$ p3 m: e+ ]3 P' P$ c% i    set-car-color" z8 a+ O+ q, l7 F/ b8 {8 _4 L5 s
    record-data
0 g1 s  E  s2 o( U, A8 H( p5 ]" j: {  ]4 A8 ~/ s/ `0 y" {* L: D; F0 x3 `/ q& z+ x
% ]" P. B- n: V+ P$ D8 l. v
  ;; give the turtles an initial speed" F4 Y. R% q) F4 }
  ask turtles [ set-car-speed ]0 v7 q5 I% @7 o* M6 `' H0 v

( V  x' t4 M( w5 T9 I  reset-ticks
0 Y, x  \+ u+ v/ w7 g3 Y7 Fend
# g9 w( K% D- P# `" B0 z4 w  O
4 f' ~2 T, _% W# i) o2 u;; Initialize the global variables to appropriate values/ Q% U, L( T6 X( ~' h: f( w- g
to setup-globals( ?+ b$ Q& b$ m: g
  set current-light nobody ;; just for now, since there are no lights yet9 E: X/ h. `/ I0 U2 Z& S
  set phase 0
' t! ^$ W' K  x/ |( r) ^  set num-cars-stopped 0
( X1 v9 ]2 V& }( @/ D  set grid-x-inc world-width / grid-size-x
1 {/ z2 i2 i, y; w$ u+ \1 o8 S3 j8 k  set grid-y-inc world-height / grid-size-y0 S# ]1 x* Z6 R/ {, I) Q! h8 v
6 j  R% H1 h+ n7 I0 c( z' Z
  ;; don't make acceleration 0.1 since we could get a rounding error and end up on a patch boundary3 q% v3 g- d+ w: A2 S1 |" _: h
  set acceleration 0.099' P% @- _( Q9 f1 z8 L6 I  M
end
7 n: l. i- \4 m5 O
$ v/ q) D/ u5 w& }" z1 f' L;; Make the patches have appropriate colors, set up the roads and intersections agentsets,
9 P$ {  f9 h1 b, r, a1 b& A8 a;; and initialize the traffic lights to one setting
4 K* W) ^' A1 D$ E5 J9 {to setup-patches
3 a3 H7 S$ y3 @* b3 j2 v8 J  ;; initialize the patch-owned variables and color the patches to a base-color
& y3 k$ X7 Z1 f" G1 z* P  ask patches
" @% t- J, f( z. ~  [
8 G" y! O! n: u5 @( H% T, U" A% C+ X    set intersection? false2 s( r  u6 H- B, f- x( z# Z1 r
    set auto? false/ N/ {& y) c8 _  }$ k/ ?' {
    set green-light-up? true+ G) M6 f6 a! G9 T" r
    set my-row -19 y( ]) p2 m6 ^* i7 d" ]
    set my-column -18 c: |/ J- W0 w9 U
    set my-phase -1
: k* D) F$ t2 ]  @  F* s7 S    set pcolor brown + 3! N) t2 I3 v5 m: g/ L  j4 M2 [
  ]8 @6 q8 V7 u4 t& T6 c
  l: U5 j3 k5 l( l
  ;; initialize the global variables that hold patch agentsets% I2 w0 U# X+ u! l  G/ K5 B- y. o
  set roads patches with$ e3 r8 J/ O" ]. q! V
    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) or
% }7 S6 ~) _7 u" U* y* ?    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]
4 e) N5 r$ q' U* k% p& w8 ~  set intersections roads with( E, A: Y. K' k* Q
    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) and
8 `. J6 N$ D! L    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]
6 w1 P- T7 d( [, w3 H
( {' m8 X- C4 I( q  ask roads [ set pcolor white ]6 J4 J+ {7 F! P! O+ _4 q
    setup-intersections
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其中定义道路的句子,如下所示,是什么意思啊?6 B( X) e/ i$ W8 P" z/ A, m* m
set roads patches with/ {7 E- i/ f# G3 b. H9 u7 F1 g
    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) or3 P. q+ Y6 k0 z% z* M
    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]  l3 n( }7 _, Q. |) I3 }2 R; M
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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