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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。7 |$ b5 w/ v% m; L/ C
netlogo自带的social science--traffic grid这一例子当中,
6 F7 [4 f  C2 ~% Fglobals
% E- z. O6 D: a) R5 a* u[
* e* }* S& c1 S; K, u2 J; M& h  grid-x-inc               ;; the amount of patches in between two roads in the x direction, V' l( w! `( B
  grid-y-inc               ;; the amount of patches in between two roads in the y direction' O6 P' T& [9 t) X
  acceleration             ;; the constant that controls how much a car speeds up or slows down by if- T4 o' V- |7 t% u# [
                           ;; it is to accelerate or decelerate
+ @  h1 r+ D4 m  phase                    ;; keeps track of the phase6 K$ S1 ?+ i) a* s# [3 Q
  num-cars-stopped         ;; the number of cars that are stopped during a single pass thru the go procedure/ ]2 K+ p2 E; }/ D1 J+ F
  current-light            ;; the currently selected light
9 b5 V2 ~: ]5 [# C) l) N- I! z4 }" Y. C1 n" r
  ;; patch agentsets+ Y; V  y& K9 e$ x" R# n
  intersections ;; agentset containing the patches that are intersections9 }9 O7 m6 ^! [: `, i
  roads         ;; agentset containing the patches that are roads" G) A6 Q* f9 [+ n- r7 q
]
: N* T7 V) M/ i2 H5 z8 X
, r8 I3 m* N6 f+ K! s+ ]turtles-own
/ l8 z, Y# X) U' X. d7 L[
6 c6 N' x: G' K  g4 F+ z  speed     ;; the speed of the turtle! {6 z; G" j+ i- }
  up-car?   ;; true if the turtle moves downwards and false if it moves to the right8 r" U. S7 M- W0 Q" t: A
  wait-time ;; the amount of time since the last time a turtle has moved
/ J7 Z/ p3 m% m( v, b, s. c2 j, \]
) n, u# D! P5 p/ _: C3 e, c; c# A5 Y/ I
patches-own2 p# v6 |/ {: d* f, ^, V5 i3 w! g
[
+ G; O8 Z1 x1 H1 ~  intersection?   ;; true if the patch is at the intersection of two roads
9 S4 p# K! V  j' J7 W  green-light-up? ;; true if the green light is above the intersection.  otherwise, false.
9 K0 t9 h1 c/ ^$ {: g6 t" k1 k                  ;; false for a non-intersection patches.( z( `- V* J( H
  my-row          ;; the row of the intersection counting from the upper left corner of the
3 ]! O9 R" i, h& \                  ;; world.  -1 for non-intersection patches.
) q6 P' V2 f+ d/ n8 l- @3 P  my-column       ;; the column of the intersection counting from the upper left corner of the
" n) ~' j. a+ n& Y; ?2 A  y8 y1 p0 i# |                  ;; world.  -1 for non-intersection patches.
8 K+ i) u3 w' f, P0 Y6 c  my-phase        ;; the phase for the intersection.  -1 for non-intersection patches.
; x+ w/ q7 L# a; S8 u0 i6 Z8 o  auto?           ;; whether or not this intersection will switch automatically.
4 V/ i* D. Y6 ]! U2 n9 |' D' i8 E                  ;; false for non-intersection patches.
( |- H1 b- T2 W3 g]
) a% {$ X. P) t$ p
: i% Q+ B* A2 ~& H! S+ ^
) M# c: e8 z" v! o;;;;;;;;;;;;;;;;;;;;;;
' t4 C" z1 e0 Z3 E' a6 I5 ^;; Setup Procedures ;;
& P' g8 h$ n3 U: f& h;;;;;;;;;;;;;;;;;;;;;;
  j1 J2 P$ I. y, z& @3 o! O+ J' O- O3 T: \% E
;; Initialize the display by giving the global and patch variables initial values.
$ c: P0 q7 v) S8 l;; Create num-cars of turtles if there are enough road patches for one turtle to
& F' T, W8 Q, |1 Q* Y% _% y5 W;; be created per road patch. Set up the plots.
: [9 j1 e: r: P; {8 ato setup4 \$ Y0 o: L: w& ~  P
  ca
% h, S& W7 o$ u4 C  setup-globals( H8 B3 \0 O& v+ z# P

; ?0 w- f. k+ w. s0 O+ \  ;; First we ask the patches to draw themselves and set up a few variables
$ i$ T  ?! z) l4 g  setup-patches- d* n* s9 w5 F1 z, P
  make-current one-of intersections- W5 l1 |5 P- L) U4 u
  label-current
+ ?9 M1 L4 L6 k, `* G0 r- S1 m! g6 v  z* j2 N" `& t) k9 ?
  set-default-shape turtles "car") T( @$ m5 V' c: T$ h. y
/ v+ @* B6 x4 L3 [. B$ \: q2 i9 J0 ?6 b! o
  if (num-cars > count roads)
5 ^. k# m8 t6 F: G( u! \- [& K  [2 m+ l' M3 w5 k' W  Y
    user-message (word "There are too many cars for the amount of "  \7 ?: |7 P: w8 l# Q6 a
                       "road.  Either increase the amount of roads "
; y- V7 R  T) e, E" U4 R, @                       "by increasing the GRID-SIZE-X or "
* M) a- W% T+ ?  v6 t8 B+ t                       "GRID-SIZE-Y sliders, or decrease the "
8 m" V) q; j8 @# U7 N                       "number of cars by lowering the NUMBER slider.\n"
3 E' T1 \& x% @$ i                       "The setup has stopped.")" U) V! H2 m5 l( {! q+ l/ z. V8 c
    stop
6 s; Z5 f2 e8 d! {! E' E/ B  ]
, N- l# S+ U0 C# t# \: i" m$ F  o$ t* J0 m8 [; J* I
  ;; Now create the turtles and have each created turtle call the functions setup-cars and set-car-color1 L8 a6 U& b: H- `! ?
  crt num-cars$ ]0 n% S7 s; W1 @& h0 k) a
  [
8 U! c7 L( A% u2 c8 z8 g    setup-cars7 m/ T: A; y; v: E% B3 E
    set-car-color
7 I; s2 w2 x  I; o$ ?    record-data
+ ]- ~2 B  l! W; J' c  ]
, d6 [5 y: h! S, d6 `
. Z( H3 @: O' Q- z3 J: E  ;; give the turtles an initial speed! j; x. d2 C7 [6 |5 s5 [( o
  ask turtles [ set-car-speed ]7 ?5 j  b8 R9 w2 T  Y' W
* F5 o$ ]: i4 z+ y
  reset-ticks0 ~" i9 R7 ~+ X' z5 c: D6 \
end
% X$ C: E5 E5 N' y0 S0 Z* Y% i
& j) ~1 D$ K; ~1 z3 Y;; Initialize the global variables to appropriate values$ \, ]" ^# |, H
to setup-globals7 x* u& Z* C! Y: _" k! I
  set current-light nobody ;; just for now, since there are no lights yet
+ F+ ?5 o4 p, z( j5 @; w  set phase 0& c4 x0 m/ Q1 C% n
  set num-cars-stopped 0
# n& j( _9 m3 S$ d) G7 i) s# l0 X  set grid-x-inc world-width / grid-size-x5 D9 o' Y' T7 @9 S* a" P3 _# A
  set grid-y-inc world-height / grid-size-y9 _# R) z6 `% T8 V& j8 T
# D4 {$ z3 i6 j. V; o4 v% Y
  ;; don't make acceleration 0.1 since we could get a rounding error and end up on a patch boundary2 M; e  q0 Y7 c; C+ o" i
  set acceleration 0.099) b5 s2 q4 h$ X$ p) S
end- p# z  C/ }, s3 k
7 t, v: {9 e( h- o# i6 t. G7 s
;; Make the patches have appropriate colors, set up the roads and intersections agentsets,: |! m# z9 X9 t3 {
;; and initialize the traffic lights to one setting) J) s3 |0 L4 n7 J$ U; c9 H' \
to setup-patches
' [$ H8 f3 K) q9 h  ;; initialize the patch-owned variables and color the patches to a base-color
  W1 O7 X3 |3 i: I5 i" T  ask patches
  K2 a5 g+ `2 p! r; l  [
9 s7 ~3 D+ \( p/ t    set intersection? false( k) Z+ y& s  A( y' m" W3 @+ Q
    set auto? false
, k* V0 {- B8 p0 l0 Z- i    set green-light-up? true
8 L+ U6 d& c- M+ U9 ~- b    set my-row -1! g# l8 F" h* k+ i3 }& }
    set my-column -1# ^) {+ u! \3 I- K( D* k5 {9 o2 A
    set my-phase -1
. u3 G2 A* c& i    set pcolor brown + 3
! T& b0 Z/ K- V5 F! Q0 U" E4 {  ]1 q  z* }+ O/ I+ \% Z

* ~3 n  w4 o3 s# I) A& c6 m5 K  ;; initialize the global variables that hold patch agentsets' G3 P$ \, T2 @
  set roads patches with" ]1 B0 z  Z2 j* w5 K
    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) or1 G, V# m7 s3 k4 N
    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]
, C# J; o6 @+ z  set intersections roads with
1 b. Z2 i* s! U8 q4 r1 J+ D3 l    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) and
8 e3 q) c- X8 Z, N" A# K' C# ^5 Q    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]
' o6 K* @5 D$ Q2 T/ W: @0 M/ Q5 v1 N
  ask roads [ set pcolor white ]
; w. D, Z; C$ g3 `5 w. P    setup-intersections1 ^0 J  G. M9 @% R% f' W$ K
end
) ~( ?8 U0 G+ f  Q4 T4 R- l3 F其中定义道路的句子,如下所示,是什么意思啊?
) V+ r( U$ ^- b0 B set roads patches with7 F5 C8 K8 Y5 t- b3 F: ~
    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) or
( {7 [9 C8 t9 p. I4 U    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]
# F8 K" Y  x/ _5 n3 w1 C9 H+ P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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