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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。
: `6 f+ z1 {. w  ^1 y) r  |+ Wnetlogo自带的social science--traffic grid这一例子当中,
! I' O3 d  a9 ^! g, hglobals
: R1 `$ ]0 z7 ]/ N) k( O# S[
" y/ p" \+ ?3 D; |  grid-x-inc               ;; the amount of patches in between two roads in the x direction$ x  V- S: l2 `' z% g
  grid-y-inc               ;; the amount of patches in between two roads in the y direction* U) P+ C. A" y1 B5 |* ]- y
  acceleration             ;; the constant that controls how much a car speeds up or slows down by if
( B  B" S) m2 y3 z* [8 z+ q* T                           ;; it is to accelerate or decelerate( \7 Y/ ~- G7 @/ c! ]
  phase                    ;; keeps track of the phase' H% @9 D8 S3 P" B
  num-cars-stopped         ;; the number of cars that are stopped during a single pass thru the go procedure
/ u- |" q9 g9 A9 k+ U8 t* y5 J  current-light            ;; the currently selected light4 w3 v9 o# }) \+ c7 b

9 R) c6 s- D2 X5 i) w  ;; patch agentsets5 o% g2 c' a1 Z  v% m
  intersections ;; agentset containing the patches that are intersections
6 w  W0 L; J% m% M  roads         ;; agentset containing the patches that are roads3 C. ~& v$ R0 o! e
]
* @4 D2 j- l* }1 G
: l5 v9 h. f$ J4 Q9 z4 i) B7 Pturtles-own# P4 r: Q/ r/ g5 c
[% V: a: g9 B3 s1 Z
  speed     ;; the speed of the turtle
& \9 [+ z  G7 x  up-car?   ;; true if the turtle moves downwards and false if it moves to the right
. r* S2 I% O0 H" ^1 C0 C  wait-time ;; the amount of time since the last time a turtle has moved
: Z7 `8 K, n/ X]* W* A! J" _3 e: N
7 ]& j% d; S  d
patches-own1 A( s! R: J8 v
[
& _& Q0 ~6 O9 C% S# }  intersection?   ;; true if the patch is at the intersection of two roads
: q; s1 _: V  Z+ ^  green-light-up? ;; true if the green light is above the intersection.  otherwise, false.+ K) E( Y$ \* ?. {: a8 A
                  ;; false for a non-intersection patches.1 l  |; n' ~, {5 j& C  K" |
  my-row          ;; the row of the intersection counting from the upper left corner of the
7 c5 t3 ]2 p/ H2 s, U                  ;; world.  -1 for non-intersection patches.
5 t  B! S3 K: y7 r9 y: F  my-column       ;; the column of the intersection counting from the upper left corner of the
% [0 h- b1 l3 p% R                  ;; world.  -1 for non-intersection patches.
5 G4 \7 \$ @1 c4 S  _& d  my-phase        ;; the phase for the intersection.  -1 for non-intersection patches.0 u5 `( G9 b9 n! }8 y4 X
  auto?           ;; whether or not this intersection will switch automatically.* I% p$ T. }# [
                  ;; false for non-intersection patches.
3 T0 C0 j& c4 a$ `6 W2 T+ F]
; U/ E0 W" S$ |8 @1 i. H
  |) X% R& ?- A7 q
" Z: l: B. A; A1 m( f; b6 a" F0 J+ L;;;;;;;;;;;;;;;;;;;;;;
7 A' p$ b2 i! S' i) L;; Setup Procedures ;;* [2 ~# K6 k: A
;;;;;;;;;;;;;;;;;;;;;;
7 _* j' d( `! o  Z5 T
1 P& t9 b$ s* K$ h* e;; Initialize the display by giving the global and patch variables initial values." g) F0 B3 K/ ~0 j
;; Create num-cars of turtles if there are enough road patches for one turtle to/ V: m" |  P7 W, s" [2 a- J' E9 d
;; be created per road patch. Set up the plots.
6 a9 u. h3 I) k$ {, w' {2 S+ oto setup) A. M- o$ K, t
  ca, _) o6 q4 O; U. H
  setup-globals
5 U  S6 {  y  g3 x5 D" [. X8 D! E: x' i, D
  ;; First we ask the patches to draw themselves and set up a few variables
5 y6 w" D0 t! Z" l4 `. H$ Q  setup-patches; U8 |& l* ?2 e3 K. W' H" ?
  make-current one-of intersections8 N: u- h; k( Q6 A6 ^3 |
  label-current: k' k0 m; L+ G% W* f: v

# ?4 k. a% o  r6 E3 Y) V: c  set-default-shape turtles "car"
- B! B) x2 m8 k! B: }% }4 o% }1 q" Z# P8 p" L& ], W9 Z; Q+ l
  if (num-cars > count roads)
) e4 z  g% R; i* }5 \+ l% u1 q  [
+ ~) C9 R% q: E; L( X    user-message (word "There are too many cars for the amount of "" o2 U/ Y. X- g* x9 d$ h4 C
                       "road.  Either increase the amount of roads "  P: c" o- x$ \0 I& [1 U. k0 Q
                       "by increasing the GRID-SIZE-X or "; w# ]- c' w/ L. Q1 r
                       "GRID-SIZE-Y sliders, or decrease the "
: _- O1 M  I. V$ W                       "number of cars by lowering the NUMBER slider.\n"
3 m, [3 p) Y1 j2 [% W                       "The setup has stopped.")
6 S. C4 ?, n5 J6 h* T# N0 _# p0 E    stop
9 C, w: w$ N  r8 \; s" [" H  ]( Z8 S5 R. @0 z) m) X% G9 R* S1 c
+ }1 D6 o5 C9 i
  ;; Now create the turtles and have each created turtle call the functions setup-cars and set-car-color& O6 I+ f& y# L
  crt num-cars
1 l! s0 J1 ?$ z4 N- v+ L  [
) k( w' H9 V8 f2 B' C    setup-cars- t6 H# ?. k1 d% o7 D! ?1 G5 B) b; h
    set-car-color
( m% }$ h" t/ p    record-data5 j0 P4 o' w; a/ s3 n% }
  ]* R/ M6 t' I. t$ J* L
3 j6 S& D; k: S1 D
  ;; give the turtles an initial speed8 ]3 Y2 K" Y- J8 J, M( J( d
  ask turtles [ set-car-speed ]# w% ^$ K" _' ^. Z" Q: D+ t
4 @7 H& J0 [6 @8 p" d9 Q. ^
  reset-ticks
4 \/ U  [( M6 L2 {* ]" rend
: p  p( g# S9 h; _( P7 b2 m4 ]2 V1 H& E4 k/ [0 e
;; Initialize the global variables to appropriate values' w- S# d7 v8 `. @$ c
to setup-globals% _8 {: e( f4 `: v1 S
  set current-light nobody ;; just for now, since there are no lights yet
& m- [* j$ e. s/ |  set phase 0
, i2 N: X5 G# h" T+ O$ ^  set num-cars-stopped 02 W8 l- d( ?$ G
  set grid-x-inc world-width / grid-size-x
9 j  J0 a, c& a$ j, |3 t  set grid-y-inc world-height / grid-size-y4 O- v% T- Y$ d' x8 y$ F( s
9 }/ r+ J1 B( K3 S5 _
  ;; don't make acceleration 0.1 since we could get a rounding error and end up on a patch boundary
% e4 P* T) P, r# [  set acceleration 0.099' g+ C5 e( p: V5 E6 ~3 g$ _0 E
end# N6 z+ |2 }, T' p( p; c
6 @! a( ?! A% |) ~" R( z. _
;; Make the patches have appropriate colors, set up the roads and intersections agentsets,
2 F! A" C. b: s/ i4 S;; and initialize the traffic lights to one setting
( f9 G' h# W" Eto setup-patches
/ E9 h4 M* R( t( T5 q& }8 g  ;; initialize the patch-owned variables and color the patches to a base-color) L6 Y0 d* Q' O  q: s1 z
  ask patches# n' Q. h+ j/ Y1 Y9 \0 S
  [
6 g+ @; C1 D3 }1 a    set intersection? false0 b% ?) X' {1 Y- d+ M
    set auto? false0 y3 z3 r: }6 L( u( z: \
    set green-light-up? true% i8 A3 h8 p* I) i3 [: ?
    set my-row -1
' `& l$ D) _7 H2 b, X    set my-column -15 b/ h- E/ k0 g6 B1 H; F
    set my-phase -1
/ f2 U' j/ `. R& u1 }    set pcolor brown + 36 ~0 u! c! \- c& R
  ]
- D7 w/ a! [. h9 ?8 {9 d# N3 u$ l7 |7 C. n1 {
  ;; initialize the global variables that hold patch agentsets
" a- z7 k4 ^% x) v) f1 ]  set roads patches with  O+ N+ l7 Z* Z
    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) or; V5 J( h8 w, h
    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]
4 J4 p7 S1 ]% v) @3 [  set intersections roads with6 _/ ?) K$ {% p$ O! F! Z1 B
    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) and
* o, E6 O* J* t5 r' e" m; `% v    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]4 e( d% B6 P8 ?; c

" @' a! Q2 P* s- S  ask roads [ set pcolor white ]
. z( C' V  ?( P    setup-intersections
' [! s' R$ X; q, R/ ]end1 t! F% C: G+ D
其中定义道路的句子,如下所示,是什么意思啊?8 |! d2 u+ r1 y& T' R6 Z1 m8 z
set roads patches with" d$ K! A* y& A% {; w- W
    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) or
! E/ E9 m) W2 u) c3 _- X$ n    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]
# i# @, `( L  X% Y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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