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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% ]  G; ^6 ?- P. y! E3 }: `
netlogo自带的social science--traffic grid这一例子当中,( h% s1 p" e- {1 Q" c8 d
globals9 c7 U% d/ j2 Z- m6 a4 n
[% U5 P% |) c- N& z2 `( e
  grid-x-inc               ;; the amount of patches in between two roads in the x direction: K: i3 g/ t7 ?: E% F  |6 ]
  grid-y-inc               ;; the amount of patches in between two roads in the y direction2 J( N9 n8 h; q( Y% k& ?
  acceleration             ;; the constant that controls how much a car speeds up or slows down by if
! [2 A4 |- L3 K                           ;; it is to accelerate or decelerate* a4 `! X$ P; ~8 \4 f; y3 b
  phase                    ;; keeps track of the phase
; c7 I, _. d0 o5 q, q: ~: Q6 c- g. o- B  num-cars-stopped         ;; the number of cars that are stopped during a single pass thru the go procedure/ }1 Z/ k( e( ~. @3 a; W
  current-light            ;; the currently selected light
- i7 f6 h: O- d! K: G, `& k' G, r4 d; t' o
  ;; patch agentsets, j. V3 Q4 @4 _) m8 B
  intersections ;; agentset containing the patches that are intersections! {# n) |" T( x% T5 n0 N
  roads         ;; agentset containing the patches that are roads
! N$ v* d& k* Y' s]5 ]8 Q' [+ B, C7 d  _9 p( f
: M; \$ p  q' o0 Y9 Q) P
turtles-own# x, v9 `* g* U, f; |4 j  C. J" D
[
' {8 s5 ^( Q0 O" i/ O4 r  speed     ;; the speed of the turtle' T2 `- Q' v5 c8 V! ^- E8 ~
  up-car?   ;; true if the turtle moves downwards and false if it moves to the right/ q, o% g: m7 ?1 A3 f0 ^
  wait-time ;; the amount of time since the last time a turtle has moved
. _5 l! o6 G" x' v. d; Q5 L% ], p]7 L' l* Y# L: B4 h0 y/ ^- U# f

+ F! q1 X6 P4 _7 E8 A! @& c( hpatches-own' k2 X$ T7 o/ N1 Y
[
3 r. J4 C& r: G% |/ d0 I* h* a. R  Z% N  intersection?   ;; true if the patch is at the intersection of two roads
$ R/ m" i3 b% J% y  green-light-up? ;; true if the green light is above the intersection.  otherwise, false.
3 e, M1 {  l1 J& f8 c8 M0 I                  ;; false for a non-intersection patches.& P. ]: b, A2 U- L* ]5 O
  my-row          ;; the row of the intersection counting from the upper left corner of the
" p4 }- R+ i3 Z' N- V2 ^                  ;; world.  -1 for non-intersection patches.
' y" W. |+ E# q0 U' r4 t; T  my-column       ;; the column of the intersection counting from the upper left corner of the, k5 g( t! M3 T
                  ;; world.  -1 for non-intersection patches.
+ x" C& c$ @9 F/ b* `  my-phase        ;; the phase for the intersection.  -1 for non-intersection patches.3 C8 @1 q3 G9 Q& v7 r8 U" d
  auto?           ;; whether or not this intersection will switch automatically.
% Z. z  C2 p% B" ^+ W, A                  ;; false for non-intersection patches.4 t, Y- I! O' G
]
" f- |8 A/ ]" \, I0 t# G2 ^4 D' E* O. P
: S" a% |" v1 h0 s* z
;;;;;;;;;;;;;;;;;;;;;;. B* s7 @3 c* K* @$ k9 D% P
;; Setup Procedures ;;
9 P. W0 E: d) O- H. b) [0 }$ H;;;;;;;;;;;;;;;;;;;;;;' G4 ?4 G+ ^" A% K. [
. Q2 }- h8 F  M: l: m: R" S! t" Z9 [1 p
;; Initialize the display by giving the global and patch variables initial values.
0 j" m( A- Z( j. ^2 [;; Create num-cars of turtles if there are enough road patches for one turtle to; D$ }0 }3 ]3 f3 `- _3 F- P& l& `& w5 E
;; be created per road patch. Set up the plots.- u  x4 O+ L9 Q$ |: X
to setup9 i( g( v% M8 f
  ca) U5 O) h  v" v" C7 j
  setup-globals) `6 Q6 @6 l6 S! n$ N/ O
( V5 ~) M+ h* l
  ;; First we ask the patches to draw themselves and set up a few variables
; T8 o! `& p& A9 l& i5 U. p( U  setup-patches3 |) Q# p6 n- j& t- L- ?+ m
  make-current one-of intersections
2 W4 \5 T0 r( `( m$ D  label-current
# a- f; ?, X  J& n2 q& _
# {, Q2 ]+ f( ]1 o0 ]5 C  set-default-shape turtles "car"
2 r( I7 s' `: m" Q. F5 r6 g% d/ t9 M: ^7 W& r5 h
  if (num-cars > count roads)) M0 D" _* Q7 [; R$ s
  [. }! |9 w+ `$ ]6 R2 t
    user-message (word "There are too many cars for the amount of "
) F' ^" r% E: |* T( X                       "road.  Either increase the amount of roads "
0 U8 X( O) j. q4 d                       "by increasing the GRID-SIZE-X or "
9 E" d: r7 |5 n5 d7 o                       "GRID-SIZE-Y sliders, or decrease the "$ {1 I. a" O% \1 \
                       "number of cars by lowering the NUMBER slider.\n"
; Y+ ~  ^0 O. h  I& l                       "The setup has stopped.")% ]* l& ?; N# [
    stop+ K4 u/ Y! x: q" ^! L
  ]
( ]( `0 N- r+ ?. |
" e# u+ G  n% ?& T# G8 ^" y1 _  ;; Now create the turtles and have each created turtle call the functions setup-cars and set-car-color
2 R: Y: U2 Z! z  o  crt num-cars
+ y- E) g+ F, [! f% q  [
. i0 E3 B+ v. h! T# @/ i- U$ F    setup-cars
4 x, |; e) K2 E    set-car-color
/ S- z, f, k, o, n) C0 q; ]9 X    record-data
" C, k. ^2 J& B  ], M" [. P/ ~2 a6 j3 {
, ], z0 l/ j3 k/ b+ e; j
  ;; give the turtles an initial speed
) y' k4 }& H6 y! U  ask turtles [ set-car-speed ]
7 v: U  O- a- o& v" Y0 Z& Y4 Z( H& E8 F3 Z0 J
  reset-ticks, q6 R" A5 o' b4 r, K( {1 K' W
end
& `% {0 ]# \& ?/ x+ S* W6 N5 [2 c8 p6 s7 K% D% r+ V
;; Initialize the global variables to appropriate values
  _. D; n* r5 y2 {" C# Jto setup-globals
# d" T* ~0 T( q$ ~  set current-light nobody ;; just for now, since there are no lights yet
# N6 I4 L+ p) Z  set phase 0
# E0 d4 v( d: j4 H  v. j3 ^# f  set num-cars-stopped 0
3 H7 \* Z# `; I  set grid-x-inc world-width / grid-size-x0 ~( r8 \8 X, h" o3 K+ Q
  set grid-y-inc world-height / grid-size-y4 }) R6 _/ p- L# a: [: Q
3 }% J' y& q6 b' c" ]
  ;; don't make acceleration 0.1 since we could get a rounding error and end up on a patch boundary
7 ^! o. _, |% w, |0 J- @  set acceleration 0.099
: Q- l5 J1 G# g; y! D2 M  f8 Vend
# P2 [" R" C/ [1 c( k) k5 {: w; F4 O7 D3 R, v) R; N
;; Make the patches have appropriate colors, set up the roads and intersections agentsets,& P! X- i9 w! R+ k
;; and initialize the traffic lights to one setting
' q! V5 c  B5 f8 t1 Gto setup-patches& z# i+ P% q9 N/ t
  ;; initialize the patch-owned variables and color the patches to a base-color
# [, I& i/ ]! e3 N! e* ?! J& t" i  ask patches' O6 l6 ^( H/ X: I, n: E
  [
; h5 Z$ e# n1 X) d2 C8 U    set intersection? false
. r* Z3 F3 v! R    set auto? false: w$ t! c4 f1 i2 B
    set green-light-up? true
+ c+ j; n# X- G' k' C' Z0 u    set my-row -10 M6 F" q( ?" h$ ]# e: o
    set my-column -16 s$ K/ S, p5 S. Z- h" o/ a- _6 a
    set my-phase -1% m3 }; {; S; ^# Z/ n. ^. f
    set pcolor brown + 3
$ l% f9 _# m% ~9 I; a) x7 Q  ]% k2 k% ^2 J8 H( g
3 L" S* ?+ h7 @8 V" U% c
  ;; initialize the global variables that hold patch agentsets, {% Y  t1 f* D0 J4 _
  set roads patches with6 [3 ]+ E* Y8 t/ T! F1 U. W
    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) or
6 h  D; Q! p* f5 U  C. b. I4 T    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]2 w  B0 S; t" n7 P4 V. P  ?
  set intersections roads with& s( _2 l0 a8 t; x! m5 A
    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) and
9 c' e. O$ f- m7 Z& u* ?3 n, L  L0 s    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]: M* b8 O1 `+ s
& z5 z# ]) R  ~" }: F( `
  ask roads [ set pcolor white ]+ m5 }  F: n: s* K9 Y
    setup-intersections
, z7 c( H4 [2 q. Fend/ Y! x$ P" \) o+ k6 |
其中定义道路的句子,如下所示,是什么意思啊?
$ z  \3 j9 W: T6 o! Y9 { set roads patches with
. p5 T8 x$ ~. g+ n9 o4 d& m0 `3 y    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) or
  `: T9 S3 `" w) }4 J5 ^    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]1 c& T/ Q( \/ N6 m, o2 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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