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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。4 m7 \. d2 H7 x! @2 V
netlogo自带的social science--traffic grid这一例子当中," F2 {. }4 {+ ?: r& H) r2 L
globals
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  grid-x-inc               ;; the amount of patches in between two roads in the x direction
3 \2 `7 z( n" F- t5 e# l% [  grid-y-inc               ;; the amount of patches in between two roads in the y direction
1 |( {" j3 |: E) A( d  acceleration             ;; the constant that controls how much a car speeds up or slows down by if
$ @$ K5 h0 M  h                           ;; it is to accelerate or decelerate
2 r' Z) P" s" d3 H7 {  phase                    ;; keeps track of the phase
5 g* Q! Z3 j# {* r  num-cars-stopped         ;; the number of cars that are stopped during a single pass thru the go procedure) ~; C0 K' b2 {2 q$ D% D% W' P4 Q
  current-light            ;; the currently selected light; H: [$ u$ o0 S0 y  T2 B- r1 s

: b4 p8 N, j+ F& ~) G  ;; patch agentsets
' p# V% P8 H# T  intersections ;; agentset containing the patches that are intersections
: }# A/ {7 k! ]& c+ _: f% C- j3 @7 q2 [  roads         ;; agentset containing the patches that are roads; `( p( v/ N. b4 b' H% l2 J- g
]
% H6 _& Q1 H2 S/ U: [" d8 _& m1 U3 E6 V( I( \) j  Z: d' G, c
turtles-own
: Q3 B$ v6 C0 m& w; r[
& m2 K! P- s& C! ^- h5 H/ Z& q/ M  speed     ;; the speed of the turtle
7 ^6 ~) z+ I5 F2 {2 [3 {2 r  up-car?   ;; true if the turtle moves downwards and false if it moves to the right1 R7 ^* o* U9 z8 N
  wait-time ;; the amount of time since the last time a turtle has moved
: O! }, Z/ X" m]4 z& j, j; o5 g6 J: i! V( L/ o
  A+ N" I9 R; E  j& a5 \) a  f3 E
patches-own
' W( |, Q6 E! C4 t[
. `: B4 {$ v% N* e, s5 e  intersection?   ;; true if the patch is at the intersection of two roads# B* A  K* h1 @
  green-light-up? ;; true if the green light is above the intersection.  otherwise, false.
, ^5 E6 L2 N  ~                  ;; false for a non-intersection patches.
" s' P- n8 R5 _* X  my-row          ;; the row of the intersection counting from the upper left corner of the7 S+ A" F9 V1 ?5 e# k; a1 J5 x
                  ;; world.  -1 for non-intersection patches.( Y  r! [+ ?( F( {  L
  my-column       ;; the column of the intersection counting from the upper left corner of the
; N; P" a4 v% ?- i( @! V                  ;; world.  -1 for non-intersection patches.4 l8 S9 P0 m3 e% i# [
  my-phase        ;; the phase for the intersection.  -1 for non-intersection patches.2 Y" P8 T2 x+ U  Y9 o+ w& h2 G/ f
  auto?           ;; whether or not this intersection will switch automatically.) N+ p- C- m0 R; A  m- r% u" m6 P
                  ;; false for non-intersection patches.
+ R/ K( G2 _, _( v]8 |! i3 E; {% @7 M
  _" ]9 O" K& P
: C$ u$ {5 m3 R6 ~0 b. L$ f
;;;;;;;;;;;;;;;;;;;;;;
9 W! k* }% f8 _. N; u; ?3 l; q;; Setup Procedures ;;% h; L& T, B; p% K
;;;;;;;;;;;;;;;;;;;;;;
5 q3 k$ \5 O9 L/ Y* w% h2 f
: `; i$ `: w' W+ s- R8 `;; Initialize the display by giving the global and patch variables initial values.- E4 ?; i) Q! N! W
;; Create num-cars of turtles if there are enough road patches for one turtle to' {' p# l( ]  M1 _/ v8 Z- H
;; be created per road patch. Set up the plots.
' ^# |1 K. X6 x( d: [5 rto setup- T# a$ P- L& @
  ca
% Z2 }1 L' O$ j" A' `+ [, f' W  setup-globals. V$ j9 J0 W+ V" j" u
# F( s) C; o- g& z& v2 O3 l
  ;; First we ask the patches to draw themselves and set up a few variables
* k. b! n$ b6 {7 G  setup-patches
$ h/ |+ E; i& X9 T. W1 q  B: F  make-current one-of intersections) K& @+ I* P' y% P
  label-current
4 q0 Q( {& K, R& y
5 N- n0 t3 W: `3 [  set-default-shape turtles "car"& ~. x0 l5 `% R% D
' G/ ]! \0 U9 O% m
  if (num-cars > count roads)5 ]1 t6 W6 i1 h* n6 D( }- G
  [9 I. T, `& y7 [# C
    user-message (word "There are too many cars for the amount of "
/ C' H# A3 [& O3 D* e- Q                       "road.  Either increase the amount of roads "
8 \% q' h6 ]- l5 I- Q( ?                       "by increasing the GRID-SIZE-X or "
' U1 r% @- b: m; I% I1 u1 \3 I+ ~6 c. P                       "GRID-SIZE-Y sliders, or decrease the "
/ J9 y6 M% N1 K/ {                       "number of cars by lowering the NUMBER slider.\n"
5 |$ B9 U8 V: B* P$ ^( n                       "The setup has stopped.")
7 `1 n/ l* H/ u! y$ c    stop
9 b+ P- {' x' x& c  ]0 M6 D& l$ B( T2 g3 {/ C0 S
% K* y+ m% ?; g; ]- [& B
  ;; Now create the turtles and have each created turtle call the functions setup-cars and set-car-color
) L+ |  a/ M5 i1 ~1 X3 M  crt num-cars
0 O$ [0 l. |( T' S5 p  [& U6 D' V* A) x, B4 l
    setup-cars8 _/ \+ b& V0 D4 i, s( d2 _
    set-car-color% v- M( Q/ @3 A8 F1 e! Y6 a
    record-data# }* ~+ z+ e1 d: `0 O6 E3 b& p
  ]
& ^( [+ Y4 |1 T6 f9 F+ G  X. ?7 H; s1 ^. y, G. U
  ;; give the turtles an initial speed( y& |- k$ ~5 n/ @3 `6 H0 ~
  ask turtles [ set-car-speed ]
0 u: r$ A6 O; M  s, x7 x( V3 u
7 P) g* ^  a% P( H5 e  reset-ticks
: G, N) v. x. I( \7 Q! q5 eend, r5 ]& U! ]4 `: H+ u* j& l5 ^

/ ~% R' E8 {; I2 k- e;; Initialize the global variables to appropriate values
1 r: i6 F+ r. R  l7 Y6 f' ~to setup-globals. [! Q$ `, s/ c4 y: E- \
  set current-light nobody ;; just for now, since there are no lights yet
# h! N/ P4 t- F) x  set phase 05 k4 D  U6 o/ C$ W
  set num-cars-stopped 0
8 T! I  G% v# w  l; w9 p: h  set grid-x-inc world-width / grid-size-x
6 I# a# Z$ J( [  set grid-y-inc world-height / grid-size-y
, W  l7 h- N8 q1 p/ G+ G% g8 c2 h9 {& U; p4 o
  ;; don't make acceleration 0.1 since we could get a rounding error and end up on a patch boundary
# ]* S6 B0 k' }5 ?  set acceleration 0.099. N5 k3 @- z1 |7 Q+ n, {% ?/ e2 s
end+ N  a5 T$ u- i8 o! x
- M. ?; w  O; ?- y( u
;; Make the patches have appropriate colors, set up the roads and intersections agentsets,
* L. B, ~" J1 W# g+ y* n' k;; and initialize the traffic lights to one setting: m" Z/ r  N3 P8 @
to setup-patches
8 X! o6 ~0 n. i5 v: j( S  ;; initialize the patch-owned variables and color the patches to a base-color6 A+ o0 K6 Q% ^- ?  J; n6 v$ k
  ask patches
* {2 Y2 X3 `7 }3 C( z5 d  [
5 g* i7 t, j; I! f0 \    set intersection? false
' ?  ~/ c) Y8 Q  I2 m    set auto? false
; Y( h& N9 R% B5 J2 d8 ~    set green-light-up? true
8 d1 [. g+ H" T$ Q, g    set my-row -1
5 n' Y/ G5 Q) ?' Y0 F, e) R) {    set my-column -15 c8 e0 D/ u9 ?) l
    set my-phase -17 [: I, d: W/ D* y: S, T& r# M1 d
    set pcolor brown + 3' ^9 [( B, D5 r& v" T: y' h
  ]; z! F* ^$ ^3 ~/ [$ v/ L& `

# j: D8 D$ q1 N: E  ;; initialize the global variables that hold patch agentsets
9 r! Z1 L* _! @& f$ z  set roads patches with8 p" K. Z0 H- y$ a6 E! L# j
    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) or/ A- ]) y9 W. T# K1 c+ B: Z
    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]8 ~* \5 c: B& J. b' y. ^9 B4 n
  set intersections roads with% x) k+ }  _" C
    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) and- a& P. g, K4 F: ~4 U$ k
    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]8 m+ {8 ^, @- d/ S6 o  m& L

2 T2 m8 n4 N8 F. V2 x  ask roads [ set pcolor white ]+ y1 M- G; r1 a; f6 L% ]
    setup-intersections
4 T1 X: r" [# b2 x7 E) F8 d* Jend
; B9 y  Q2 R" Q" [9 _7 z; ^) E( J其中定义道路的句子,如下所示,是什么意思啊?( x. U4 ]' @' l; B# g% ]
set roads patches with
) N- u' }4 k  N7 o' f9 P+ \8 H* z    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) or/ [( q2 ~# x( @% n+ \9 v
    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]
$ t% s3 ]0 I; ~! j! [1 E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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