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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。1 Z& x5 I/ E1 a& r4 x8 t, @
netlogo自带的social science--traffic grid这一例子当中,! s' J0 Q. P" P/ X
globals
* A% a. _- p; |: W: G' }  _" a2 D[
) S0 s0 [% |" o  grid-x-inc               ;; the amount of patches in between two roads in the x direction: O9 v- K8 }- u( @
  grid-y-inc               ;; the amount of patches in between two roads in the y direction- V- P- |: C! z
  acceleration             ;; the constant that controls how much a car speeds up or slows down by if
, Z: I6 c* `) o. g                           ;; it is to accelerate or decelerate
4 [" c# d/ l) U  phase                    ;; keeps track of the phase' P3 U+ o( z+ S! C. M$ A
  num-cars-stopped         ;; the number of cars that are stopped during a single pass thru the go procedure- o1 D+ K4 K0 x' q$ N/ X9 }
  current-light            ;; the currently selected light
/ |/ E8 x6 H) H" d) j6 _. o8 {6 f4 @  O% G
  ;; patch agentsets; t9 i- N$ H$ q" u. R: x: Y
  intersections ;; agentset containing the patches that are intersections6 v; p3 o: R7 C9 k% @, g
  roads         ;; agentset containing the patches that are roads5 x* C8 ]4 @7 Y
]4 r* |* J3 V+ u/ _/ s

$ J8 D- d1 Y/ l, jturtles-own" s' c: e$ U/ y8 x; n8 u
[
+ s9 y3 P- ~5 K: ]0 y  speed     ;; the speed of the turtle
4 Y$ f. N& ~) @6 z  up-car?   ;; true if the turtle moves downwards and false if it moves to the right
& f0 i" @" k! A% P/ W$ h  wait-time ;; the amount of time since the last time a turtle has moved  K1 W+ A) g' n& t! Z4 ~
]$ L' M$ g8 W- a& p8 @5 @! o2 T" S
% z9 T. e& W+ c" m6 y5 {
patches-own
* `; T% x0 {: m3 m2 @6 I[
+ ]" t0 j1 @. u, X. B9 f  intersection?   ;; true if the patch is at the intersection of two roads
' J1 A/ v) [. _  green-light-up? ;; true if the green light is above the intersection.  otherwise, false.7 C. c* o( \: j
                  ;; false for a non-intersection patches.
( P4 v# R/ Q2 \# ~/ u, s- K0 A  my-row          ;; the row of the intersection counting from the upper left corner of the9 `. H( ~9 Y0 W: u
                  ;; world.  -1 for non-intersection patches.7 `4 ~5 Y! W- p4 d
  my-column       ;; the column of the intersection counting from the upper left corner of the
9 i: Z( o  Y8 ^- f! I* I! F  t                  ;; world.  -1 for non-intersection patches.
( ^9 j9 O9 f) T% J7 d* B2 J9 {  my-phase        ;; the phase for the intersection.  -1 for non-intersection patches.
) Q5 |1 u- K1 r( r5 x+ D) e  auto?           ;; whether or not this intersection will switch automatically.9 `8 y# w* {. R/ u7 g
                  ;; false for non-intersection patches.
4 |! Z6 o% P. j2 }! v8 v], z/ s, a1 f# x. j$ O6 l# j1 _

2 x2 D; g% F2 l3 c7 }
& g* x. k2 t" r" G+ J$ \8 y;;;;;;;;;;;;;;;;;;;;;;
0 t/ o# K$ _4 A1 Q7 b+ M;; Setup Procedures ;;
6 F( W# [) j6 ]3 N* D# N+ S;;;;;;;;;;;;;;;;;;;;;;! ?) [/ \/ Z1 C* g6 S3 s. R, f

  k  y. P" }5 J& f0 x: t: X;; Initialize the display by giving the global and patch variables initial values.0 F& q- Q. s2 s
;; Create num-cars of turtles if there are enough road patches for one turtle to
0 j9 m* e% g9 z$ |- v. Y$ J;; be created per road patch. Set up the plots.
) `& o! N  y) h) nto setup
3 e8 C( E# r- Q5 I8 Z  ca3 G' Q$ M" @5 h  B4 @
  setup-globals" q& O" _8 w4 m4 Q4 j

" h! l3 n0 r0 H' }( S- Y1 B( o  ;; First we ask the patches to draw themselves and set up a few variables# f4 w1 y. _9 \5 C2 M1 m7 s
  setup-patches2 z5 \$ c  Q8 B! x; U9 T
  make-current one-of intersections5 G5 Q/ x7 y+ \+ J/ [/ R
  label-current
% ]2 {" F# A, z8 p, v; d' q+ C% ^/ g/ t+ B+ j2 _8 q5 S, X. U
  set-default-shape turtles "car"
4 E7 L" W: c9 p7 N7 d8 d  v
, h* R& l2 J; z* q2 E, Q4 Q" D0 }  if (num-cars > count roads)& ]: u1 @# G3 P! H2 y. v
  [
' A0 ~( m; U  w/ y+ t    user-message (word "There are too many cars for the amount of "
9 e" v0 O" c) m" \                       "road.  Either increase the amount of roads "4 i: j- F8 B8 t. _4 O5 ]  S
                       "by increasing the GRID-SIZE-X or "* s  }7 O, |. K. j  Y, d# O
                       "GRID-SIZE-Y sliders, or decrease the "9 e$ B- U; V0 ?# c5 G9 R. Q  R
                       "number of cars by lowering the NUMBER slider.\n", h% {7 f) q% G( V8 G, _6 y
                       "The setup has stopped.")
5 R) d# U( {4 a- b; Z/ F    stop7 G1 ]# U; a0 O0 D8 V  `7 H% \7 h
  ]( m6 T3 D; b) q7 V
5 h7 B- g4 n1 R- j# H; d9 _
  ;; Now create the turtles and have each created turtle call the functions setup-cars and set-car-color
. E' w' m2 d8 a- _6 K9 M, X  crt num-cars$ ^: Z/ Z; t5 j
  [
4 ?9 E9 v3 ~# j& t  d' z4 {    setup-cars9 F' E+ k2 i% k( G  d- Q# `2 s
    set-car-color
' |$ D4 u1 Z" \# J    record-data; A5 a/ w9 a- J  k9 I$ A
  ]4 P: Y* F+ V# z7 P% B6 a5 `! r

% |. z) u# v: g; k5 v! r3 ^  ;; give the turtles an initial speed
' Y( a6 `9 J% y) w  ask turtles [ set-car-speed ]: Q" W1 W: ?, H

+ w' N" S* V! S2 m2 b! x6 B! h# B  reset-ticks
/ t7 N6 Y8 B/ [" ^8 k% _end
3 `% q% y! R, M9 c- E1 z0 G6 U7 J5 N  j3 B, Z9 _
;; Initialize the global variables to appropriate values
3 P* w6 M# R% h1 S; B: E2 n! vto setup-globals* b0 \* I4 t* x$ `/ l
  set current-light nobody ;; just for now, since there are no lights yet& O1 ^& i2 T0 A2 O: f2 \) ~
  set phase 08 m; p" R6 z  r& H) s9 w
  set num-cars-stopped 05 a2 E, }/ V5 [9 L0 q
  set grid-x-inc world-width / grid-size-x. C2 b$ z$ \2 L) ]3 E
  set grid-y-inc world-height / grid-size-y4 U' f% r! d- _& Y& p& l

) a. C8 U7 h$ M$ A+ Q! c+ S5 ]6 }  ;; don't make acceleration 0.1 since we could get a rounding error and end up on a patch boundary
% q' W' J8 Y9 g- D, ~; F. n  set acceleration 0.0994 \# i! `8 q+ S2 v% Z5 \0 N) C
end' c4 C% c8 D4 v- h

  x( p, z$ a) b' `; [2 g" i; U;; Make the patches have appropriate colors, set up the roads and intersections agentsets,* d: f% X# T% `  M  U
;; and initialize the traffic lights to one setting
9 m( z( ~# k/ }! I! ?- Nto setup-patches- f7 H& t8 H2 {1 L
  ;; initialize the patch-owned variables and color the patches to a base-color3 }4 Q" V. i; M3 K
  ask patches
7 D) p6 `. `) X% w  [
  @, {# c( Q. o4 Q    set intersection? false( b* {6 t7 a4 K1 i0 E
    set auto? false
! W. Y" m# I. I. o    set green-light-up? true
) L2 f; ^2 K, a- x    set my-row -1; F9 R( G* H7 o/ ?
    set my-column -1
" B  P( v2 _& O- F0 Z8 R    set my-phase -1
1 g" g* C# {% l( o3 i) t    set pcolor brown + 30 d7 k3 N# E4 v& G( h- D$ \, `. ]
  ]/ X0 `# ^3 i' T$ B1 J1 ?. v( w
* X3 E9 G' K$ j0 u4 h" V
  ;; initialize the global variables that hold patch agentsets' U8 v, U# g! i+ }
  set roads patches with
5 _; N  k+ f0 }9 |, l    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) or
2 j: N7 ?) P7 @, P/ N: w8 H' I    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]- q3 ?" k8 d# s  V
  set intersections roads with
" O) v" D8 }8 W. l2 `2 Q    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) and
. N" `! ~. w. {. I: Z0 F  }4 v, \: \    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]) X6 y& W+ Q1 g: u( `

+ G# T- d+ ~. p. ^  ask roads [ set pcolor white ]
7 A) J$ P0 D; g8 e- u1 l/ w8 v    setup-intersections: [+ \; {# T' W  U# K# B
end' e2 I( A: m& Y4 T5 u# J8 k8 b
其中定义道路的句子,如下所示,是什么意思啊?
0 a1 ]- e. A' N7 O set roads patches with
2 E! x! z7 _, Z4 n$ p- {9 z    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) or
2 ]& V3 B. R5 A; X5 O; F    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]& t9 H. c! T; s; ~1 M8 [
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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