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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。
# R/ r( A  U# j0 x4 R' o/ E0 p& Jnetlogo自带的social science--traffic grid这一例子当中,
1 O+ C% l) \% Q% s& Q8 }$ Qglobals
! j) O- u. E# k/ p* C$ K[$ [2 M7 h& t# s; A0 a% H
  grid-x-inc               ;; the amount of patches in between two roads in the x direction
+ a3 E) D$ A$ _8 Y  grid-y-inc               ;; the amount of patches in between two roads in the y direction
+ ?( V, \+ M) [# o/ V% d9 @6 H  acceleration             ;; the constant that controls how much a car speeds up or slows down by if
) f/ H1 a/ I4 }" f( ~/ i0 D5 h' t$ b                           ;; it is to accelerate or decelerate
9 U) f, }6 e; h6 \* m" D' w  phase                    ;; keeps track of the phase+ C& I2 t- g2 @
  num-cars-stopped         ;; the number of cars that are stopped during a single pass thru the go procedure
, ~+ o% a4 }/ q5 W& q9 `0 j. u( J% F  current-light            ;; the currently selected light, J* }' ?4 @% l9 t9 @1 s( c
' w. U) }0 }! i
  ;; patch agentsets
0 D5 i' s$ @8 F  intersections ;; agentset containing the patches that are intersections
# M0 g$ y: l8 J/ A  roads         ;; agentset containing the patches that are roads
/ a& O1 _3 J% h- d$ O2 C; ^7 f]
" j) f7 \+ j. J6 ]) O4 K6 W6 u& W! a* w) D2 `  h
turtles-own( U' n2 d  B0 Z2 u2 m1 C
[. {% A( S0 _0 m3 u/ c
  speed     ;; the speed of the turtle
7 k/ H) S: y8 y" r5 f  up-car?   ;; true if the turtle moves downwards and false if it moves to the right: k# {0 r) v/ Q& z- W8 U# @
  wait-time ;; the amount of time since the last time a turtle has moved7 W' ?1 @( ]* ?
]5 y# k: p, }2 p! s
3 n2 N' L7 ]9 \$ P
patches-own& @5 Q6 k6 P, ]/ R( K: l
[
7 o: E9 n8 F/ {$ I+ u0 k  ]  intersection?   ;; true if the patch is at the intersection of two roads
* a( C  j% G7 y  green-light-up? ;; true if the green light is above the intersection.  otherwise, false.
0 f; v, O( c; U# f5 x4 {! e% }. L$ z                  ;; false for a non-intersection patches.& a9 O' P6 L# Q: X
  my-row          ;; the row of the intersection counting from the upper left corner of the( O  i  F1 T) w" M/ z  i
                  ;; world.  -1 for non-intersection patches.
* a8 ]1 u' Q& z  my-column       ;; the column of the intersection counting from the upper left corner of the
1 @. V1 @- H$ t, |                  ;; world.  -1 for non-intersection patches.( U7 C9 U3 o: }* G4 T" A1 i3 ]
  my-phase        ;; the phase for the intersection.  -1 for non-intersection patches.
! k- \! e0 y& N3 M/ ^  auto?           ;; whether or not this intersection will switch automatically.
; q, \7 L# ]$ @* y) \! v' d4 c' j                  ;; false for non-intersection patches.
8 K4 w1 t: f; O$ o- C/ F$ _0 |]
5 ~( e  \: _: |: Z  u& d. j' K- s( f. ]0 R4 s, ~
8 l5 Q8 x+ _5 P% V4 T
;;;;;;;;;;;;;;;;;;;;;;
& R" F8 N% L" f: X3 ~. h, ?;; Setup Procedures ;;
( R$ M+ a6 g& H9 a* m: D9 D: O;;;;;;;;;;;;;;;;;;;;;;
. J4 `; ^# i5 Z5 _! n# N
# a. K: _# G/ K6 V: Z0 h;; Initialize the display by giving the global and patch variables initial values.% ?  M2 r- o0 f: l
;; Create num-cars of turtles if there are enough road patches for one turtle to
$ c; ]6 L& R, `. _" |;; be created per road patch. Set up the plots.
! L% c3 e% Q- f& Lto setup
  E2 [. \( ]" u% f3 r% |. o  ca" Q" [% n! L9 T& c" U
  setup-globals
3 u9 i- ^, q0 K) u2 ^) E- l6 |/ O) Z" S
  ;; First we ask the patches to draw themselves and set up a few variables1 [% C4 R& z8 {' G
  setup-patches
% }+ E3 l* H/ P! Z2 B, T  make-current one-of intersections
% l+ b. z/ I+ z' ^9 O' h5 x; {" u  label-current
, ?! M1 w% o) @8 F! j  u4 ?/ Z! k2 G* A, [
  set-default-shape turtles "car"
' R$ t% G& `& v& U0 ]( T0 a' E5 U5 k) |, |: N$ D
  if (num-cars > count roads)
/ W$ t2 s) [6 Y0 N" Q' N+ k  [
4 w+ ^- m9 L' A5 I7 W    user-message (word "There are too many cars for the amount of "+ s+ B' F6 S* R% P" \1 D! p
                       "road.  Either increase the amount of roads "
/ i9 Y: y+ x" T0 q: J5 Q                       "by increasing the GRID-SIZE-X or "
; ]9 S# O% v! K4 x5 x                       "GRID-SIZE-Y sliders, or decrease the "
# M6 {) r& j' Z, h                       "number of cars by lowering the NUMBER slider.\n"
0 i+ p' b* M! r% z2 Q                       "The setup has stopped.")* h7 d' X+ H( @* @9 Y" S, x% T
    stop5 E# @& [) G& o- k5 H7 K* C
  ]2 K0 T: t" w; t6 I

. c. h2 b9 E% K8 y  ;; Now create the turtles and have each created turtle call the functions setup-cars and set-car-color% [: \( \) a- ~! k9 h% y2 B
  crt num-cars
+ b0 \/ u3 W; R  n+ @: p  [
% T( c+ R) O. q3 o8 d! L    setup-cars( v6 o1 w% ~5 [9 s1 }' x, o& Z2 m
    set-car-color, W) U0 Q0 W" b, ^9 x! f
    record-data
: m# r9 Z: S1 X1 Q( {* b! ?" w  ]
* W4 d) {# h- O5 U: k  }2 M5 {5 C
, \, U5 ]8 ]  V  ;; give the turtles an initial speed
5 B" M& p# z6 S0 _5 X+ U  ask turtles [ set-car-speed ]
2 F# d: _& O* ^% w/ o) |
8 \4 j. X# h$ B  reset-ticks
7 O1 S) Q% \  p. t; r, eend) s# g9 ]  M! T6 R; f
) ]4 R  D; @7 ]5 H8 J1 M9 x2 i7 H5 }
;; Initialize the global variables to appropriate values  [- M! ~- W+ t
to setup-globals
5 Y" G& S7 W& F6 X# J$ L  set current-light nobody ;; just for now, since there are no lights yet3 R: x" [) K9 L0 e7 A+ n; A9 u
  set phase 0; _; A6 T* c/ [% O1 B
  set num-cars-stopped 0
' ?5 D( w% B+ j  set grid-x-inc world-width / grid-size-x4 p, F: T2 y% K( `! e* V
  set grid-y-inc world-height / grid-size-y
( M8 C4 R) Y: W$ C* h3 c& ~
- ^4 M$ v8 h  j8 ~2 k: ?  \  ;; don't make acceleration 0.1 since we could get a rounding error and end up on a patch boundary# a$ M7 B, Q, g/ @. F5 k+ `. c# |
  set acceleration 0.0993 t9 a+ v% R; q
end; v9 K/ s! @4 r5 ~, E1 c
( p0 f9 ^( O2 q* j  A( }
;; Make the patches have appropriate colors, set up the roads and intersections agentsets,
2 ^1 e4 W7 l1 @6 v) Q, h' y3 d;; and initialize the traffic lights to one setting' G1 k: F+ x) g/ y9 u2 Z$ q0 M' M, E
to setup-patches
4 e# H% B, k9 C, c0 x) Q# H6 `/ E  ;; initialize the patch-owned variables and color the patches to a base-color
8 n) M- k2 S6 a( r5 J1 p( e  i. ]  ask patches/ [, d- D' F. B+ H
  [
7 m- |5 N6 j3 Y# G6 G    set intersection? false
' _0 y4 x: w4 i% ~. d$ c    set auto? false
' I' L) O! Q. V2 _! ^    set green-light-up? true
* h! P: ^& z, M' p. U# I4 X6 U9 I    set my-row -1( ^  X  @4 u8 V$ J% `; n: g
    set my-column -1
; o+ Z1 R0 B/ J7 |6 V    set my-phase -1/ v. K1 Y3 H: K* s2 V1 B
    set pcolor brown + 3# F) B9 Q  o" ]$ s+ k4 \' t
  ]
, E7 A" k8 Y" f5 q0 \
! O0 k( ^9 I' b% A, G" i6 V" ]  ;; initialize the global variables that hold patch agentsets& m4 h, R  R7 A; k- w
  set roads patches with; W0 T, d8 Q/ E* @: b% A. c
    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) or
; C" `  i+ R$ D6 b% N5 i" \& F    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]4 ^0 A& V6 w/ u$ w
  set intersections roads with/ x) [4 z4 E  Z, ]7 ?( W+ P
    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) and
. n4 {: J& }3 J3 F+ P    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]
) ^; E. K) E4 r) u8 G6 a. \
. Q4 t, k0 e; j  O4 x  ask roads [ set pcolor white ]
5 G' j6 {- L0 h% j/ ^: `' L    setup-intersections
# g# E0 z$ Y3 S& Z! C# Q, q  \. _end
6 X1 ?5 {. M6 l% i其中定义道路的句子,如下所示,是什么意思啊?+ k: h7 n$ p5 ~4 |% i
set roads patches with
" X3 w! f: K* y8 R/ n0 f# B    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) or
4 J6 e" x. v  E    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]
- a% A/ V$ ?. F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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