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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 P* I: M0 ~' @0 I6 `netlogo自带的social science--traffic grid这一例子当中,8 m( L/ d9 P* @% E& g$ t6 J
globals
( B( i, n7 S- r! V7 v[4 }4 Z* {8 U' R, n3 s
  grid-x-inc               ;; the amount of patches in between two roads in the x direction: B( E% |6 K  m$ y& [& G5 D
  grid-y-inc               ;; the amount of patches in between two roads in the y direction
0 H" m, w( Q% B8 V$ L. a$ B  acceleration             ;; the constant that controls how much a car speeds up or slows down by if* ^" c# k# G) y! y
                           ;; it is to accelerate or decelerate
3 l9 a: Q' i  T+ [. g; K  u  phase                    ;; keeps track of the phase8 H; T" }' E# F* ?& ~
  num-cars-stopped         ;; the number of cars that are stopped during a single pass thru the go procedure
% P$ c, Q( w. ]2 b/ O. H  current-light            ;; the currently selected light
! w; {- l- J5 w! J; X9 n( Y2 @
8 b0 L. F# Q" a! W5 q# U  ;; patch agentsets
) `$ Z" O- n3 j# ^  intersections ;; agentset containing the patches that are intersections
/ g3 a' Y0 A$ i% i( Q5 b0 D  roads         ;; agentset containing the patches that are roads8 D% |9 G5 y9 {$ e' C# F
]
- B) R/ F. v# I( P% b$ D7 U* X* w7 X
turtles-own9 h1 o3 [+ W/ A9 [( Z. r( J
[, ^1 C4 y" Q2 Q3 \
  speed     ;; the speed of the turtle
: g; G0 D6 y8 ]; f  up-car?   ;; true if the turtle moves downwards and false if it moves to the right
; `) W3 T# L2 E  G  wait-time ;; the amount of time since the last time a turtle has moved
0 `  x; c1 \* K) ]0 P. V1 A]7 t$ C, W5 Y, d* k5 D7 I/ S
" N# `0 A" D) d' t  ?3 ~
patches-own) B. S8 I  C8 y/ z6 A% w
[
3 l/ R. v" p. ]. _" {+ T  intersection?   ;; true if the patch is at the intersection of two roads
& Z: E0 y- b! E- @; `" o  green-light-up? ;; true if the green light is above the intersection.  otherwise, false.. H* @* L* `6 s; ]6 Q" A
                  ;; false for a non-intersection patches.
+ i( j* r* p9 j( o# }  my-row          ;; the row of the intersection counting from the upper left corner of the+ R/ W$ P: t- H9 f; `9 D
                  ;; world.  -1 for non-intersection patches.
1 s4 Q+ B, D; Z/ B  `! B4 E! D  my-column       ;; the column of the intersection counting from the upper left corner of the
3 s7 Z# u8 e# _! N* \                  ;; world.  -1 for non-intersection patches.
5 ~* C5 T$ {! @3 S  my-phase        ;; the phase for the intersection.  -1 for non-intersection patches.4 Q5 s1 d* h! S7 o( i; f% |
  auto?           ;; whether or not this intersection will switch automatically.9 q" _( U( O+ Y/ k: v# a" g5 a: S$ }
                  ;; false for non-intersection patches.; J* m, m5 ?) \
]5 M" i5 T9 R) u. D& c4 f

% @3 g- ?* d) s% l
) c$ b2 T5 f' t7 S" ^" t;;;;;;;;;;;;;;;;;;;;;;
( H) J1 d( |+ v; S& @- N/ {6 j2 E;; Setup Procedures ;;
% e5 ?" |* z& Q' G& Z$ e  F;;;;;;;;;;;;;;;;;;;;;;* g* A6 X. M4 a' v; a% Z
  \2 D8 {9 x0 S4 b" t! V" @3 |) Q
;; Initialize the display by giving the global and patch variables initial values.& i/ ^0 A; G  U8 R
;; Create num-cars of turtles if there are enough road patches for one turtle to1 q6 U3 q0 ?" D4 f" \
;; be created per road patch. Set up the plots.
6 Z, a7 G% }4 J3 H9 Kto setup) ]: }: u5 q& S; X, e3 S9 u
  ca5 j. V6 p2 ]: e' S  Q
  setup-globals
4 e6 F( h# r. e( o" W
! @  e9 D  j; n  T/ I# s7 y  ;; First we ask the patches to draw themselves and set up a few variables
6 z0 Y( u1 G+ P) b- M8 s' y  setup-patches- V# P. e; `8 b8 c; U2 M* v# W
  make-current one-of intersections
& l% r3 L  B. v, I  label-current& y; Z0 p3 @1 A& F$ G2 I

" @# G( r5 c+ m. f  set-default-shape turtles "car"
' R+ H; K8 W5 s. Q- A$ h! a2 P8 B! n8 X- S9 u2 v
  if (num-cars > count roads)4 m. _1 r% {' |  B" ]
  [. u4 |/ Z+ D4 Y, A  v8 A2 x1 q" q/ B
    user-message (word "There are too many cars for the amount of "0 _+ m+ o; W1 y! {9 T
                       "road.  Either increase the amount of roads "6 {/ O0 K; T4 Y- a' M
                       "by increasing the GRID-SIZE-X or "# J( I/ @  ?4 X, g( ]! m
                       "GRID-SIZE-Y sliders, or decrease the "
" Z8 H; L$ r1 \3 [6 ^9 _* C/ `* B                       "number of cars by lowering the NUMBER slider.\n"
" n- A2 W4 H. d2 V, h                       "The setup has stopped.")* L; x" D. J9 c  J$ M: s
    stop
' b$ q7 G. v# V' D  X  ]5 }) R7 Z7 o) k1 @' a7 X) B# ^! k+ W

; }% l: S/ c5 h" O; s  ;; Now create the turtles and have each created turtle call the functions setup-cars and set-car-color/ e$ Q( x* W4 c# S5 l
  crt num-cars( I6 F; g# Q8 q% L5 C/ l' z. b
  [; b9 Q  T) m% a0 `7 w6 d
    setup-cars
4 @4 W7 j" F* I# ]! M2 x( X    set-car-color! Z3 A+ H+ h1 `# G& a
    record-data. ^4 B2 _  |, y
  ]
7 t7 v& y& m* d! U5 H) r/ ~: n6 l* ?1 ?4 Q. v
  ;; give the turtles an initial speed4 y) M$ ~" Q6 O2 p& s" t+ r
  ask turtles [ set-car-speed ]
2 p; D1 h. @* X5 G8 h9 f( S0 L
4 h; S! C4 Q. B0 S6 i  reset-ticks! g% p3 Z# c2 L4 h, T1 _3 R
end
. Q. S1 f  W: x/ P" M7 _7 y6 e
8 \( {8 H- e1 n% q;; Initialize the global variables to appropriate values& z6 S: P) X/ J1 x+ g( Z
to setup-globals
0 A4 A' H3 X8 H( N  i" ]0 M) A+ R9 `  set current-light nobody ;; just for now, since there are no lights yet
2 R- ]& Z% P8 G) ?" h  set phase 0
5 c6 E& H1 V9 ~) {: `1 g  set num-cars-stopped 03 z( [6 s( N; s
  set grid-x-inc world-width / grid-size-x
# u* y; D' `( Y% W3 H( V  set grid-y-inc world-height / grid-size-y) R% }# x7 P; m8 n, ]

* g( X1 @0 o& Q. ]% v' _) T. a  ;; don't make acceleration 0.1 since we could get a rounding error and end up on a patch boundary2 _- E) K) U8 o
  set acceleration 0.099/ r  l1 J2 k5 g8 W' d' A5 [
end# ^" w, }6 r% k) F

$ R* Q0 r0 o- y% C7 X( M: o; };; Make the patches have appropriate colors, set up the roads and intersections agentsets,2 F' B0 r2 `# J0 @, A+ P+ x
;; and initialize the traffic lights to one setting
5 R& \* m4 p: C" b5 U! @: jto setup-patches4 t2 T6 J' M. V# O
  ;; initialize the patch-owned variables and color the patches to a base-color
( S8 `) J$ A6 _# E  ask patches2 A) Z; U8 j6 N4 b! I
  [
4 `3 E7 S  S4 ]! u. e    set intersection? false
+ A! o* R. j: P; Y" F    set auto? false
$ X4 E  w; b+ G( n3 T7 o+ O    set green-light-up? true
" c$ ~( O: Q6 i% N9 w; g) k    set my-row -1& k! P) }' T3 C
    set my-column -15 @" z9 I' z1 B4 ]
    set my-phase -1
- k- Y$ ]- h+ Y1 h- l! N$ P    set pcolor brown + 3
2 {4 M% g0 b; p$ A6 \, K  ]
4 J, z) I) V- F* ^+ h6 M. C: J3 O+ z" M' U6 P
  ;; initialize the global variables that hold patch agentsets
1 b! v7 q/ |* ~0 n$ a  ~4 g- g  set roads patches with' w" W8 P% ~+ X5 c4 S& s: q
    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) or$ s  L( C+ H: e. H
    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]
( f  N! q$ k% O2 _/ g  set intersections roads with, q. ~, [! D3 G$ {3 I
    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) and9 p0 T* J2 B# I6 M5 K3 \1 W
    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]
7 W2 B9 R2 z9 [7 k
; l2 D# p1 [5 [9 Z! m* b  ask roads [ set pcolor white ]3 t3 T- y* S/ W1 d- Y6 l& |
    setup-intersections: l- v9 a$ J$ M& H2 \1 V& D- K# [
end
3 @6 f/ h0 R/ K/ S* f/ r& F* ~其中定义道路的句子,如下所示,是什么意思啊?* i, g& v6 S* Y' L
set roads patches with
0 q. C8 |+ N! v" R5 L2 w8 i    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) or' T/ q4 b; N$ \& M
    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]$ h' G9 Q+ C$ t# ]6 `7 C" \2 p* i
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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