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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。& x2 p% t. a! d$ s
netlogo自带的social science--traffic grid这一例子当中,
+ d/ H$ U+ u; p' b1 d3 h, \globals$ T. Z0 [, g5 d
[
  |# c9 k8 K) M* n+ }# H  grid-x-inc               ;; the amount of patches in between two roads in the x direction5 O; o3 a3 ?  ]" o3 ~
  grid-y-inc               ;; the amount of patches in between two roads in the y direction- G" [" K3 i% N5 f) l! @2 c
  acceleration             ;; the constant that controls how much a car speeds up or slows down by if# [- R3 V; c: J+ F7 T/ K
                           ;; it is to accelerate or decelerate
' @: r" o  p4 j) Z: s  phase                    ;; keeps track of the phase
$ `' ?; O1 b9 d; K. Z" ]9 h  num-cars-stopped         ;; the number of cars that are stopped during a single pass thru the go procedure) P, R+ p# k# P
  current-light            ;; the currently selected light
. G) }+ \0 M# v% n" F$ |/ n
& L0 A9 b$ k9 Z& C2 \* K- G  ;; patch agentsets- _9 h; B/ B+ d/ g7 i0 v3 I
  intersections ;; agentset containing the patches that are intersections- m( R' J6 U  F0 ^) x0 r7 t2 D
  roads         ;; agentset containing the patches that are roads' R; v: [/ N" C. j
]- s9 l* D* L- F4 n  q/ ?

1 Y- v/ C: K. [- _turtles-own6 N0 f3 K# L' S+ B8 T8 K0 c9 V+ N
[8 n$ t, v" @. W: `1 i" [
  speed     ;; the speed of the turtle* @6 N+ L8 B# C! G# Q' \: |
  up-car?   ;; true if the turtle moves downwards and false if it moves to the right
2 l4 F& }/ l1 z3 H  wait-time ;; the amount of time since the last time a turtle has moved4 }) h# \8 l6 V2 N+ a2 F* G, g" O
]. h# }* s2 E( J' b2 V, P
7 q! g/ E) ?# ]4 N
patches-own/ ~- ?( R' P; d1 t4 y
[
2 N5 r" K. o6 y8 c9 _' b  intersection?   ;; true if the patch is at the intersection of two roads7 H) r+ R2 K5 q5 F0 u4 H# C3 K" v
  green-light-up? ;; true if the green light is above the intersection.  otherwise, false.  {. W, C6 l8 g& O7 f. R
                  ;; false for a non-intersection patches.
' x& I/ E: |* H  my-row          ;; the row of the intersection counting from the upper left corner of the
& {; i1 W4 v) `" A5 X, t5 y8 R( n                  ;; world.  -1 for non-intersection patches.  W  ^9 k1 p$ n/ v5 H1 J6 s
  my-column       ;; the column of the intersection counting from the upper left corner of the$ P' l: J9 Q4 l& u0 \" E
                  ;; world.  -1 for non-intersection patches.
% F# w4 g" N' l0 Y; N% {  my-phase        ;; the phase for the intersection.  -1 for non-intersection patches.
  f' W# k4 {, j: h# M+ ?. A  auto?           ;; whether or not this intersection will switch automatically.
' l9 c) o3 e0 L6 j, Y                  ;; false for non-intersection patches.
0 T" _, ?0 p3 j$ g5 I]
- w; ]. C. i" b+ T6 T6 Z5 S
3 v  Q% j- ]6 n& L% n5 o+ h. i
7 n2 N4 M3 \( m; ];;;;;;;;;;;;;;;;;;;;;;
6 i' t2 [+ O, @5 v;; Setup Procedures ;;
2 G  Q* x/ F! r;;;;;;;;;;;;;;;;;;;;;;
+ x" e2 m: w7 K+ Y
9 m- r2 S0 V- ?, P;; Initialize the display by giving the global and patch variables initial values.
, ]1 N+ E! ]7 y* v& F) M;; Create num-cars of turtles if there are enough road patches for one turtle to: }$ {/ a+ s- w  |' D9 a$ m) C
;; be created per road patch. Set up the plots.
1 z* ^  Q$ p2 T7 u3 i1 J" tto setup
' b- `# U: p1 H$ Z7 i9 N  ca/ f9 X6 J6 V+ ?3 V( U
  setup-globals
$ g: g! `: ]0 @$ a# E
/ R) ~& b8 t' [  O/ z% O# q7 p! k* Z  ;; First we ask the patches to draw themselves and set up a few variables! \4 I! ]+ t; ~4 [
  setup-patches
9 z* Y: n; x  V  make-current one-of intersections
/ I) T. }: c4 ^; ^& l8 o  label-current
; @! P! @* z3 o# O% S* B4 H) `  {0 B  ^# C, q
  set-default-shape turtles "car"
9 r  v% F7 Y7 W- t8 |/ F
7 J; q0 N6 J, T  ^  if (num-cars > count roads)
. }, \" a; _' t+ }* I; q  P  [
! P/ f6 `0 N: e    user-message (word "There are too many cars for the amount of "
- p2 u9 x" n0 E" Y0 Y                       "road.  Either increase the amount of roads "! k& _, j" F, p+ q
                       "by increasing the GRID-SIZE-X or "+ R  M; N5 e2 Y3 g7 b8 E
                       "GRID-SIZE-Y sliders, or decrease the "- m  }7 W, \# G7 X" c3 v# C8 b  Z
                       "number of cars by lowering the NUMBER slider.\n"
2 b' x# G/ A1 [                       "The setup has stopped.")
* j- A9 w: i& b# `    stop
: g5 s$ e2 B6 ^/ x$ I  ]
, g' N' M: f! c
3 x5 V4 j! H6 O$ X  H  ;; Now create the turtles and have each created turtle call the functions setup-cars and set-car-color2 V+ L  b; E7 K7 M0 p4 Y
  crt num-cars% Z- \7 z, y0 b! N0 T4 c
  [  i8 W- ?8 i! q1 ?" F. s4 G
    setup-cars" s1 y+ e+ ~3 S6 U7 _: d9 F( E/ H
    set-car-color
8 _; Z4 ^- o& m8 r    record-data+ F. ^, t1 i) o: U5 Y
  ]  y& O  g# _5 Z' j5 g: U4 o4 ]. V

- C1 |% k. d! r0 e  ;; give the turtles an initial speed
% _8 q& C% d' {7 `: t9 f5 n. }  ask turtles [ set-car-speed ]0 X# H$ S) }; ~7 M# }# U
3 X$ Y* _' W4 f, y$ c8 Y
  reset-ticks
* N  m6 l( T! n# vend
% h& u5 p# Z1 `7 L
2 q& r4 ^& \# ~+ g, K- A;; Initialize the global variables to appropriate values
' e* |: G1 s, z% `9 g1 b, E! [: nto setup-globals
" y/ N' u0 S5 h  O* i- [  set current-light nobody ;; just for now, since there are no lights yet5 F, p$ X8 W: {6 p& ^
  set phase 0% u* N0 S6 a$ ~7 Y; t
  set num-cars-stopped 07 s( E0 @- r1 V* J* P' Q, s
  set grid-x-inc world-width / grid-size-x" @- o6 x4 w( o+ f- g: a
  set grid-y-inc world-height / grid-size-y
" H# I1 q$ y2 \- R' r/ ~$ r& l
+ C& X+ m) U* r" |4 d  ;; don't make acceleration 0.1 since we could get a rounding error and end up on a patch boundary1 K+ r+ }# y0 G* e& m
  set acceleration 0.099
: E5 x% `' V+ s/ R/ Oend
" D& ^8 P0 r. v8 s$ `$ L$ e( i. ~9 N
, g- f. b1 o* Z- c( {* O;; Make the patches have appropriate colors, set up the roads and intersections agentsets,
) s' S( ]+ {" ~, Y; J$ [;; and initialize the traffic lights to one setting
! Y$ z4 t* ?2 D- ~( U' n/ jto setup-patches" a/ C4 f/ m$ @9 E: b
  ;; initialize the patch-owned variables and color the patches to a base-color; M# r9 S1 O: O7 `& e& a* d
  ask patches* l' Q' h* j. H" A5 \! e) ?
  [
1 ]$ \4 P# z6 R- e    set intersection? false# ?4 S* M, Z8 W, S( M
    set auto? false1 n$ y7 L  P" V8 `! i# y
    set green-light-up? true
& K9 o% p% _; M2 K    set my-row -1# ?) Q. u, G" X
    set my-column -1
/ D9 w7 f3 r8 I    set my-phase -1
" m! T( e2 s  B    set pcolor brown + 3
$ E& o7 L/ b  `2 g6 U  ]
0 X: y& X) o" N" \& p+ l5 C* G( b6 R7 H8 u
  ;; initialize the global variables that hold patch agentsets( Y1 a/ ?3 P$ i9 s& }9 U6 ]8 p
  set roads patches with
7 W3 I$ [) D( Y    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) or
5 l* \- c! f1 {! j3 U8 U  o    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]8 }# m' F+ G. l5 Y6 Q
  set intersections roads with
5 J4 ^6 g( s- {. i2 M# j1 l    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) and
% @5 {7 \1 W, M, b8 b; `$ H    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]9 x" d$ I. ?9 l* N
* w' K* {* `; X6 I% @2 W; C
  ask roads [ set pcolor white ]) J' w3 [5 E- j; c4 p6 Z
    setup-intersections
: P' m0 ~+ t) Qend
+ i2 R  a8 r! I2 M2 `, Y7 ^" D6 K其中定义道路的句子,如下所示,是什么意思啊?* B! y7 ]1 \2 I9 S- K" v9 h3 l
set roads patches with
& ^5 e! V7 I" Z) k) p; [* H    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) or* R$ W( ], p; k$ D1 n
    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]
  ?0 r& ]. X% p; Q% U# \$ h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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