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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。. P& O$ p% V- m' E: P7 l5 K
netlogo自带的social science--traffic grid这一例子当中,- v3 z+ r/ r! t4 p8 y5 n
globals
5 c3 r, {* M: c& U8 v" Y7 l6 c[  j# U# C) i" o0 K  ]$ n
  grid-x-inc               ;; the amount of patches in between two roads in the x direction
4 y4 B+ C8 L3 X) x( [  grid-y-inc               ;; the amount of patches in between two roads in the y direction* v. o- H8 b, j
  acceleration             ;; the constant that controls how much a car speeds up or slows down by if
" Z! t" i$ b. ^: K' I; I& H                           ;; it is to accelerate or decelerate
8 T; e6 F" b) o! \$ B  R  phase                    ;; keeps track of the phase1 A8 E2 r! a5 [1 Y" Z; y7 E8 a
  num-cars-stopped         ;; the number of cars that are stopped during a single pass thru the go procedure5 X* ]) L, H4 `9 |
  current-light            ;; the currently selected light8 w1 y# ~. d% s. g7 s0 I0 D

  o% J9 d, A1 E2 E4 A  ;; patch agentsets! z9 \2 t6 R4 t8 T* S5 ~' T- t+ S0 a
  intersections ;; agentset containing the patches that are intersections8 L1 l! U; b) r' L$ e
  roads         ;; agentset containing the patches that are roads# ~0 _3 U3 }' y2 D4 E' |$ V
]. m1 [& _4 J2 y- r6 E5 P
- C+ E5 P5 S, \& p5 `9 x) x
turtles-own' E1 s2 n( a, v4 z
[/ w4 e( \! q5 J) K- ?
  speed     ;; the speed of the turtle# |+ U2 r0 r5 J
  up-car?   ;; true if the turtle moves downwards and false if it moves to the right
6 i# B* \( Q& k! I5 ~9 X; J$ C8 t' l  wait-time ;; the amount of time since the last time a turtle has moved
) A+ Q) M, t  z5 S% k# E9 }' Y]
! x2 y$ h- X8 r+ t  |. j, N3 p2 q0 i0 j! b
patches-own0 K/ E* d8 O& x, B* F1 E/ r' c
[! e' ]9 {) b, j7 Y, U( I$ r, C
  intersection?   ;; true if the patch is at the intersection of two roads
+ o1 D" H% T* h& a( m  green-light-up? ;; true if the green light is above the intersection.  otherwise, false.4 Q  `, A* k/ T
                  ;; false for a non-intersection patches.
% O, I0 {8 ~: G) Y/ R  my-row          ;; the row of the intersection counting from the upper left corner of the
3 \* @1 z+ `" Q. L. I$ A                  ;; world.  -1 for non-intersection patches.
, e! c. U# [2 j8 ]( c' r  my-column       ;; the column of the intersection counting from the upper left corner of the
2 z6 v; g- c' l/ K                  ;; world.  -1 for non-intersection patches.
& P7 i+ p; c8 q+ V7 c  my-phase        ;; the phase for the intersection.  -1 for non-intersection patches.
6 X7 B1 \' b* M! g9 p3 X2 y  auto?           ;; whether or not this intersection will switch automatically.% Y) }) D: r: l9 o2 o
                  ;; false for non-intersection patches.
) I8 ?4 r  I& ?' @% w1 E- v8 L]' Q8 M2 R/ a7 ~6 s0 `, U

, J3 s, ~0 Q# t5 K! k$ d# f( U( d2 j9 b- B6 [* L- F1 q: W
;;;;;;;;;;;;;;;;;;;;;;
) e6 v# V4 T; |9 u2 M;; Setup Procedures ;;7 f' d5 r7 H( N9 ?0 k3 u
;;;;;;;;;;;;;;;;;;;;;;$ _5 b+ t: G+ M$ K

5 S  U0 W7 h5 \* z;; Initialize the display by giving the global and patch variables initial values.6 X- N1 t, G. C! t# O! }
;; Create num-cars of turtles if there are enough road patches for one turtle to
  B+ Q0 g$ Z# e8 M2 y;; be created per road patch. Set up the plots.; [* \  M* h0 F( d& N( K
to setup
) O5 f4 h) J1 W9 q: z! _9 |2 D  ca$ W* H& r  E, l8 N5 Y- Z$ J0 c
  setup-globals9 N5 I! x8 G4 E" {

$ b; q  W$ N1 P) m2 U  ;; First we ask the patches to draw themselves and set up a few variables/ A- m, g5 u4 T/ l4 Q: ~1 A
  setup-patches
6 Y- ^$ |4 V2 ~% }  make-current one-of intersections1 n9 Q' _: j" V# E5 X! O2 l% K
  label-current7 U5 \  Y' p' z0 W, e6 z
* K# h' L4 i% ^5 D0 }/ f
  set-default-shape turtles "car": d; y0 L5 T3 L8 Z

& A: z# V  c6 v; ]- n  if (num-cars > count roads)$ @. s9 s# ]9 R" \& c
  [
" K7 r" J6 ~0 `7 J* ?1 X    user-message (word "There are too many cars for the amount of "
) R# Y" b8 K3 H; V' P                       "road.  Either increase the amount of roads "
' Y7 N3 }( P, T/ z+ `9 o! X                       "by increasing the GRID-SIZE-X or "
# ]! N/ f2 \4 H, G% p7 Z0 w$ y. \                       "GRID-SIZE-Y sliders, or decrease the "9 A& X8 t4 n- B" e9 I
                       "number of cars by lowering the NUMBER slider.\n"' p) l" ]  T5 p$ Y  F# n, x
                       "The setup has stopped.")! T8 `/ s  i- o1 H& ^4 z* o9 D  C' r) [
    stop
9 k2 F* l. A/ V% x* G  ]) H. p3 H2 I# a, z$ c$ I" h& i
- O5 u6 d( A" g+ s
  ;; Now create the turtles and have each created turtle call the functions setup-cars and set-car-color
1 F- X) u6 Q- i7 a3 E# |  crt num-cars
, Z( v$ _1 Y+ g& D  [
* o* u- S" q- i8 W( g- l; E    setup-cars. Z  F# E& P$ }6 t- w: x
    set-car-color
6 O5 A3 X# j( b, y    record-data( Q( m1 ?2 u, \- q6 \
  ]% F2 K1 d6 X; l( g2 a' e6 h

! I% @  T! G; S+ w- b4 L7 r8 U& A  ;; give the turtles an initial speed+ D+ @: F1 \, t8 R  }
  ask turtles [ set-car-speed ]
: e! |: C" H6 r! A) l
; @9 K9 t4 T9 \5 M  `  p2 `& m  reset-ticks
$ Z! z6 z/ b% v& Rend5 v: z0 w9 P1 ~. `2 t" j% k0 ^' |# r' d

  I8 p# {6 O5 F" g# Z;; Initialize the global variables to appropriate values
5 p' H: {, A/ Ito setup-globals
; ^) v. Y6 _, d9 }' k  set current-light nobody ;; just for now, since there are no lights yet: g' p" y9 K3 g
  set phase 0
7 b9 m- ~! R' b0 Z% o  z  set num-cars-stopped 0
. T- ~# O& j* Z' t& m  set grid-x-inc world-width / grid-size-x
9 O  e, w, j, V( t; q7 m" _, q0 t! o  set grid-y-inc world-height / grid-size-y
; r+ D3 W% Z) A
/ D7 |: g3 d7 T  ;; don't make acceleration 0.1 since we could get a rounding error and end up on a patch boundary
5 q. u% I2 E0 M  set acceleration 0.099
  o5 X6 |+ G& |7 Zend
. S% d0 j% u6 I$ a4 t, z
9 f7 H. ?/ |1 k6 a4 \; D;; Make the patches have appropriate colors, set up the roads and intersections agentsets,
0 \: {( f! E5 a- b;; and initialize the traffic lights to one setting
! i$ r- M6 }  Pto setup-patches9 i* T0 g6 P- f: W, e
  ;; initialize the patch-owned variables and color the patches to a base-color
+ U1 z- l( y- S& l" {  ask patches
: O  W* _5 a4 y8 |9 V$ d6 t  X  [! V. X7 ]6 A! `2 `  y3 P2 I
    set intersection? false  j, s! |  {: r3 I; f, t
    set auto? false
" P9 H$ u; \& s    set green-light-up? true
) A% T; e! Z# {    set my-row -1
6 l0 G8 P7 g8 `# k9 s6 \& @' `( s    set my-column -1
& l5 D  [% X$ ]! _    set my-phase -1
+ F, D1 U6 ^& n& q( v    set pcolor brown + 36 t. \/ \; v$ ]. S! Q
  ]
8 e# M2 k8 W6 ~3 b
: J, z( `, }4 ^( A5 C  ;; initialize the global variables that hold patch agentsets
( i0 `! u! t2 {  k  set roads patches with
# @) L1 n) h! |  {6 w4 s# w+ A; q    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) or
( T5 O! j% N3 I' |2 u1 `    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]" Y& D; N+ P: Z9 |( f
  set intersections roads with
" _! y) W; A$ }8 C0 ^8 i    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) and4 k9 E: `' j- X7 p9 Q
    (floor((pycor + max-pycor) mod grid-y-inc) = 0)], b, \' n6 O' l+ Z$ |; i
$ d. k( l8 u8 ?- R8 A; g7 n# r
  ask roads [ set pcolor white ]
. t+ o1 D5 F' ?- j7 O4 ~" k4 j    setup-intersections0 T% }  K/ H4 x2 r  c1 n0 z4 C
end
4 N. a4 H2 i% z( }# p其中定义道路的句子,如下所示,是什么意思啊?& f$ _  {( u. h/ |4 [( h( d
set roads patches with; k9 S" e5 l( Y8 }# q1 k
    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) or- x! p9 V! Z' K
    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]) O$ o. g6 ?* M. C$ b
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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