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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。2 J; z; ^* x- o5 v' N( D# O  b' k
netlogo自带的social science--traffic grid这一例子当中,
* m3 T( y; a& i. k% [globals
) b1 Z, i/ ^5 A2 P[
8 \7 I$ s. G7 M4 t0 E3 Z! S5 v6 [8 R  grid-x-inc               ;; the amount of patches in between two roads in the x direction
' G' [9 h9 S- j  grid-y-inc               ;; the amount of patches in between two roads in the y direction' g$ u- M' ]/ B, ]
  acceleration             ;; the constant that controls how much a car speeds up or slows down by if
% y. F9 {; U6 N- x! D4 l                           ;; it is to accelerate or decelerate; J3 t" ]7 P" w2 ~8 B5 w6 d
  phase                    ;; keeps track of the phase7 q" ^/ H  j1 r) b& j
  num-cars-stopped         ;; the number of cars that are stopped during a single pass thru the go procedure
4 f' u$ t. s8 T% p/ s8 ]  current-light            ;; the currently selected light8 l+ K+ o; v* z3 |$ @8 G
0 L  k: F+ ^- r
  ;; patch agentsets
' H0 A" e; h' J& C% h9 h2 Q  intersections ;; agentset containing the patches that are intersections5 s( Z9 P7 |8 d, n, j* X+ {% K
  roads         ;; agentset containing the patches that are roads) t! o0 b0 c& ?) y/ o
]9 b* D3 V( b) K. ?/ V
* d( J: d- a  ]: c
turtles-own- T4 M2 ~- S3 h: n6 T
[& ~3 t( K( h7 j( D, s8 q
  speed     ;; the speed of the turtle0 V# x+ ^- j( {
  up-car?   ;; true if the turtle moves downwards and false if it moves to the right4 h6 L$ T3 t3 ]. Z$ j  D
  wait-time ;; the amount of time since the last time a turtle has moved+ S$ g: P3 M6 \1 P5 I5 B& e# J
]# b, u+ f- r% x9 F' g  ]2 m9 B

& B) x( Q9 t' G" V: u* M2 Rpatches-own
" ~! }$ z# b, r& w8 f7 M% J[
+ ~" I% h' u1 W( R# I4 R# w  intersection?   ;; true if the patch is at the intersection of two roads
0 p5 ]9 P; X, y  green-light-up? ;; true if the green light is above the intersection.  otherwise, false.
% t0 z2 l) J- c* d                  ;; false for a non-intersection patches.0 a( |( P9 [4 k. x9 \) X; R3 a" q7 [3 u
  my-row          ;; the row of the intersection counting from the upper left corner of the
; @$ b" W  x" f. g. {9 h* Y4 l8 w                  ;; world.  -1 for non-intersection patches.2 K, s. R, N9 Z
  my-column       ;; the column of the intersection counting from the upper left corner of the1 W4 x$ h, o6 j$ @
                  ;; world.  -1 for non-intersection patches.
4 e9 \& X& U# C6 G) g  my-phase        ;; the phase for the intersection.  -1 for non-intersection patches.
+ {! j0 \% {+ D3 [6 e  auto?           ;; whether or not this intersection will switch automatically.
' E5 i8 \4 Q6 B7 \                  ;; false for non-intersection patches.  O- ?5 I6 X7 x, Q' G) c& j
]: d* V; y: E1 _' ^; Y( V+ e

) P( N8 }" t3 F% f/ C7 E6 p8 R# z9 l) b
; \) d; O6 h1 J: r# A& r& v;;;;;;;;;;;;;;;;;;;;;;
- J3 j; o9 k* |7 @- i' N;; Setup Procedures ;;5 p% p# [1 o& ~! U, u
;;;;;;;;;;;;;;;;;;;;;;
) z0 f0 R9 X0 ~0 K- o  Q5 g# |5 S4 j6 _9 U" M' K
;; Initialize the display by giving the global and patch variables initial values.6 u/ V: u. H7 v0 j
;; Create num-cars of turtles if there are enough road patches for one turtle to, f7 H% ]3 g2 ?: q* w0 s
;; be created per road patch. Set up the plots.1 _: n; A( A; i2 A; i# K+ {9 U9 X
to setup6 t' \. K1 f& Q- g' |) Q
  ca
( N' ^. S- E% z& n8 g, A  setup-globals. k2 l* X, h* u. P5 K$ H

2 T3 m* W% m8 l& k: N  ;; First we ask the patches to draw themselves and set up a few variables" V; v3 e. [' M& Q! t- X& ?0 ]
  setup-patches, U# {& c( i  j/ Y' A- S$ S
  make-current one-of intersections9 j7 f3 o. h: F1 C& f9 r1 m
  label-current
7 N; f' M2 q  H# ^) R3 ?# j$ |' p9 n* H
  set-default-shape turtles "car"
8 s8 r7 h3 ~; p: @% L9 f7 j" l& x) i8 U" \( [
  if (num-cars > count roads), e- D0 {/ m8 u8 B9 H
  [
# R2 A1 A0 D" ?8 z    user-message (word "There are too many cars for the amount of "
0 R, N8 e) X, D* {& e                       "road.  Either increase the amount of roads "
  i5 N! d( ]) u! j( o( u3 P                       "by increasing the GRID-SIZE-X or "' {: O) z: a) `: _4 |/ O
                       "GRID-SIZE-Y sliders, or decrease the "
6 }. u: K5 N1 w- v; d: |1 b# d8 c9 e                       "number of cars by lowering the NUMBER slider.\n": \, V& @3 K) I6 E
                       "The setup has stopped.")
( l0 y, D: R/ y" x    stop7 i! V& f2 f5 x6 U
  ]3 W. {/ B7 @1 m" t8 ?, b: s# M5 w

2 |3 e0 B' `7 |" d6 Q* |$ C! ]3 j  ;; Now create the turtles and have each created turtle call the functions setup-cars and set-car-color
# l8 w! e% |- i1 g' Z  crt num-cars
! y, {! `6 l' A- R* h  [
- _$ B+ O: N5 G- O    setup-cars) V* W2 S8 h6 V' T6 a; O9 `3 A5 u
    set-car-color
+ x6 s2 m: J! ]  x2 R9 |7 D    record-data
7 y# L; {  S+ x& c; o( B  ]
. M8 t. |5 b) N3 C
& v2 A. J2 g( R5 y  ;; give the turtles an initial speed$ p2 [+ q2 t; K0 g! `& v
  ask turtles [ set-car-speed ]
* N  I5 v& K2 z1 W* u7 R- @3 o- E8 u
  reset-ticks
! r6 p0 K5 B3 Xend+ J: h; T5 N6 E! x% v

' Y0 I/ ?9 P6 U- m5 `, ];; Initialize the global variables to appropriate values) y. ^& P# z, x- x$ Y! N! D5 |" Z
to setup-globals  ]" B* H( ~8 z- h
  set current-light nobody ;; just for now, since there are no lights yet
  J8 E3 h2 w7 w# b9 l# w  set phase 0. R$ u  ]2 K7 _4 F2 X
  set num-cars-stopped 0
& ?- E) o, `- n) ~; G& j3 ?+ V, j- C  set grid-x-inc world-width / grid-size-x4 R" O* G: j/ x4 ]) u# \
  set grid-y-inc world-height / grid-size-y6 o8 N$ n; t2 Y5 }' E7 k- m! f
8 [% W" ]/ R7 ]! e" Z
  ;; don't make acceleration 0.1 since we could get a rounding error and end up on a patch boundary. B% }1 S. k' r) g& j1 L
  set acceleration 0.099$ n% w  E/ n* @  _9 o
end' `' w+ U# p) h: h
9 U3 z! n. _9 N
;; Make the patches have appropriate colors, set up the roads and intersections agentsets,
1 |9 S7 q0 m$ K% d2 i;; and initialize the traffic lights to one setting3 [: D7 \" E% d  y! `( q
to setup-patches: _8 E0 I+ o# a1 H3 B8 N
  ;; initialize the patch-owned variables and color the patches to a base-color& ?0 Y( y# R# t- ~6 i
  ask patches
  s# j% \9 y- g9 R! e- a1 y  [
# L3 G- P8 H9 m$ N    set intersection? false9 S" |: g& u" {# G' S
    set auto? false$ j; b$ l6 n) ]
    set green-light-up? true
& p3 n" o" K3 l5 t: a2 L    set my-row -1& I4 H' E% r. _7 N% K
    set my-column -11 T( h9 W9 Q  G9 C/ H+ m
    set my-phase -11 c" y/ k4 Q/ L7 r; @" u% {! B
    set pcolor brown + 30 c6 F' E/ r9 _' {8 S9 @
  ]  }! W4 G! p! [7 H; `# ^
" R% L6 A3 e$ ?. H4 `3 m
  ;; initialize the global variables that hold patch agentsets
) L! a' y/ s( \* L3 F: Z  e  set roads patches with
% H$ D# P: k* y& v1 `# m& ~    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) or& d) j9 J) T1 S8 o+ I
    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]
- Q' L( y3 k6 k; u* B  set intersections roads with; V/ ]' r+ \4 K" N
    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) and
" T. s, C3 j9 S" s$ F( g! y- G    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]
- `# e/ Q4 U, z) S" l: U, \8 C# m3 w
+ s" g; x" b( h# W0 p7 n, [  ask roads [ set pcolor white ]2 a- d( E) H2 E& N3 J0 B
    setup-intersections  _+ `. c- Q4 d6 Z( d. y: [
end
1 K5 E' Q$ Z3 f* c. T0 ~其中定义道路的句子,如下所示,是什么意思啊?
! i% P" f& k' B" u! J0 L2 u- Y set roads patches with
1 |) ?7 C, u# \8 V- @5 p    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) or) E0 E6 t/ b, r& K" @- I. d
    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]
5 f+ j6 n3 C1 a% g) ?8 E# t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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