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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。
8 G7 ^1 i% ?" O6 y: ^9 ^  ?; b/ l6 ^, ^netlogo自带的social science--traffic grid这一例子当中,- o. m: C3 c0 y/ `( [
globals
" _" {+ _4 P% v! t- c" K[( o+ R3 h" ], w$ h/ H, Q
  grid-x-inc               ;; the amount of patches in between two roads in the x direction6 T: k# V8 P4 q* r
  grid-y-inc               ;; the amount of patches in between two roads in the y direction
1 ?( I" L. o: y/ I; q  acceleration             ;; the constant that controls how much a car speeds up or slows down by if! H( R3 o2 i& G; [
                           ;; it is to accelerate or decelerate3 i: l6 W! E* Y/ F) n) Y
  phase                    ;; keeps track of the phase
2 h0 }! {' E" E* r7 a2 T# t: A  num-cars-stopped         ;; the number of cars that are stopped during a single pass thru the go procedure, |4 s8 d6 l" W3 A9 M
  current-light            ;; the currently selected light
) q5 f; k) z9 I% N- B  E' o2 ^3 v! e8 Z7 w
  ;; patch agentsets' R. O  d& C& D  j" O( R. _# a
  intersections ;; agentset containing the patches that are intersections1 ^7 \$ _( @/ o9 K0 L7 i+ F, Z
  roads         ;; agentset containing the patches that are roads
3 B+ \( K) s" Q+ B: I]! J) _. ?3 e2 ^
' a; l& c% l% x( X
turtles-own3 i6 a  n7 S' _+ L1 E/ |1 i
[
4 {, ~0 p; \! a7 O  speed     ;; the speed of the turtle8 f  t8 m: e" y. \0 n/ e
  up-car?   ;; true if the turtle moves downwards and false if it moves to the right+ \3 J% P4 o% K% M+ l
  wait-time ;; the amount of time since the last time a turtle has moved
& w7 c' R3 p% c* J5 L]
4 Q% `/ I9 l1 h& J4 z
1 O/ ?. ?/ C% B7 N( }( Cpatches-own
% i- Y9 l6 g) v8 p' G0 o/ e[" l5 @# h2 A* k" v
  intersection?   ;; true if the patch is at the intersection of two roads3 j( q0 F( t) ?
  green-light-up? ;; true if the green light is above the intersection.  otherwise, false.! C7 r, p" s) a
                  ;; false for a non-intersection patches.) I" v1 [3 K3 H
  my-row          ;; the row of the intersection counting from the upper left corner of the2 `# G" B$ h; x" \6 o$ Q
                  ;; world.  -1 for non-intersection patches.
' _8 }7 M. `- i7 }+ N3 f+ q6 [  my-column       ;; the column of the intersection counting from the upper left corner of the" y6 Y0 y2 f% U, w# I9 ?& |5 D$ X7 W
                  ;; world.  -1 for non-intersection patches.
) t  d* U  h% U1 e. n' a  b  my-phase        ;; the phase for the intersection.  -1 for non-intersection patches.
6 k- a% C  O  K6 n+ b8 {4 w  auto?           ;; whether or not this intersection will switch automatically.2 A, H. S% v& t+ z$ B
                  ;; false for non-intersection patches.. y7 o$ G% F' a0 e1 [+ U- I
]
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' Z3 w8 S! e' i4 D9 J) W1 r' @4 Q% M  t% j, Z0 B6 X
;;;;;;;;;;;;;;;;;;;;;;8 y+ m* ?5 x5 {1 O
;; Setup Procedures ;;
4 f7 B8 e  k, I' e% Y8 L5 K;;;;;;;;;;;;;;;;;;;;;;% o& d5 L1 Z4 a2 }( N2 @

$ D% Z2 i6 ]# j& l2 y% y, ?: a;; Initialize the display by giving the global and patch variables initial values.6 J: U  ?5 k7 L( @
;; Create num-cars of turtles if there are enough road patches for one turtle to
2 ?1 J! f# M" k/ h7 c/ H;; be created per road patch. Set up the plots.
% X/ f$ ?5 N  l5 x& N0 R! h1 D2 dto setup
* D* W) x. o, {8 W- ?! C1 y3 I  ca
% F' U5 O8 n! I7 v3 |. A' b  setup-globals
3 v: e- `2 `$ [1 D+ I, E2 L: m! o
8 s6 I5 J8 f0 [/ [1 A2 ?- c; O  ;; First we ask the patches to draw themselves and set up a few variables
8 h$ \! C$ S9 h* D( _% a- e9 c! K1 g  n  setup-patches
$ J% i7 Q9 X' s1 ~  make-current one-of intersections3 b9 h/ @( c& [3 F8 v, J8 i0 X( Q
  label-current" q) I# V  J- K+ F3 h
% ^! H6 c5 [' Y9 z5 v5 D! ~
  set-default-shape turtles "car"
$ W/ R/ B9 a1 ~2 G9 J: h- v7 |
0 y! B1 ?" T* V( S  if (num-cars > count roads)4 U+ y, m# S/ ^: b
  [
" v3 b- x9 T" F* R+ o- o7 g    user-message (word "There are too many cars for the amount of "
: b) f* \: j2 o! J                       "road.  Either increase the amount of roads "
' c: z+ }: ^- X                       "by increasing the GRID-SIZE-X or "% e% ^/ m+ y9 @9 J* q* E' P: r8 f
                       "GRID-SIZE-Y sliders, or decrease the "
8 k! j, s3 A7 J/ w% Y                       "number of cars by lowering the NUMBER slider.\n"1 I* c- V: \3 \. S
                       "The setup has stopped.")
; z3 }& }3 j% Z& M& J/ x' ?    stop+ {, x9 Y+ O' h( S# _: z
  ]
& ?& S. D+ w# f  x- p6 b+ t$ c1 `& s/ _0 R! i/ v9 Y* n1 f. G; k
  ;; Now create the turtles and have each created turtle call the functions setup-cars and set-car-color
3 @% s' Y$ [* k2 a  crt num-cars) J8 l! {* l+ q, t, R$ a( Y# r+ R
  [2 `0 T8 F% I$ x6 y  Q7 S% n
    setup-cars
3 b, ~- I4 ]0 B6 T6 [) W& ^) K4 H    set-car-color
- l  F! |3 D+ g! t* W    record-data
& M* w: Z( C6 T2 h7 U  ]5 n7 i' h+ {7 C
8 s  x+ K# [( a+ V3 y' a$ X
  ;; give the turtles an initial speed, g% u2 m3 |, P2 ~
  ask turtles [ set-car-speed ]! S5 E. L, p9 N, C8 t" L2 p8 ~
) L3 \, `  ^3 I, b! b, F
  reset-ticks) a2 Z) f' J: J# U! U2 D( R, {
end
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7 p) {6 B: D" k0 @) V: v6 q9 F5 n;; Initialize the global variables to appropriate values
5 P+ s! l7 X( B) C3 K7 b9 C, @to setup-globals
" n6 Q4 Z  [# ^/ Z- ~3 O  set current-light nobody ;; just for now, since there are no lights yet! m/ l) d8 }. z
  set phase 0
, z  F' f! H; I* X3 T+ r6 P  set num-cars-stopped 0! G6 K; _% C, [7 t* P) Z4 }* o
  set grid-x-inc world-width / grid-size-x4 i& w4 m+ E, d7 y! U6 D
  set grid-y-inc world-height / grid-size-y5 ^: U5 V1 }& o6 n/ H

. D8 b8 z$ a) G$ ]% e  ;; don't make acceleration 0.1 since we could get a rounding error and end up on a patch boundary( C% ~! H/ s6 W1 b7 @
  set acceleration 0.099; `  {+ Y5 b8 ~+ i2 `2 |3 N/ J
end6 n, O8 V; z! X7 y" B

, P; Y7 C2 S( t; |" n3 r# Y;; Make the patches have appropriate colors, set up the roads and intersections agentsets,  c0 i6 [% H- z, d6 n" `
;; and initialize the traffic lights to one setting
5 a0 E3 D  o' @) a& m/ Ato setup-patches
, y- ~6 R* L- Y  ;; initialize the patch-owned variables and color the patches to a base-color
- L* U4 {6 U8 W4 }) y* p1 M  ask patches$ L6 T' q2 W% {
  [
" p3 ~8 n+ ~/ @; ]. ?/ i    set intersection? false+ O4 o- K7 b# [
    set auto? false
. B3 s3 C4 v- i* D    set green-light-up? true
. d" x) z6 X; D. X  F$ k" d$ [4 `    set my-row -1
9 S+ L% @/ ?/ O/ w+ V- Q    set my-column -1
6 w" \/ V- D+ Y( s6 X    set my-phase -1) ^5 [! V. P  ]& e/ P1 V
    set pcolor brown + 31 L' ^+ B( ?  j* L0 }: Z4 I4 U
  ]
* x( V* f* H& a1 [4 B/ }5 ]
; A+ h* i& L+ _. r, s  ;; initialize the global variables that hold patch agentsets' M) M& ~8 z' u/ d3 L( V6 c- t
  set roads patches with
9 i0 P7 I( m( @/ _    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) or( y' @- R1 H( J2 [
    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]
1 Y6 u1 P+ o' H# J5 k7 z  set intersections roads with- C1 D# z7 v+ t8 w: F$ N: \1 @. n( \
    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) and
9 z9 Q' `. \$ Q0 h1 R7 L    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]4 d# f# m2 k) G5 z+ a' o# l+ ^

+ b+ s1 j( ]/ K* N; A* w# S6 D% ~  ask roads [ set pcolor white ]- y7 ?7 g/ _4 i8 ^9 \! r% ?1 i9 R! b
    setup-intersections
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其中定义道路的句子,如下所示,是什么意思啊?# X' x, Q: {, o3 u: t
set roads patches with
# W; l- U  {4 V# K& B& i9 g    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) or: n1 Q5 B4 f2 \- ~/ W. z/ X" A! F, M9 \
    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]
. v7 E2 R& s% r. A2 A8 R; O, Y* 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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