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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。
0 l; w7 J0 z' c) q# k! a. Anetlogo自带的social science--traffic grid这一例子当中,
: I" _3 U4 G( p  ^5 x* uglobals
* q+ e& v$ z4 X& g& G# [[; X0 {" Y6 U9 ^, j
  grid-x-inc               ;; the amount of patches in between two roads in the x direction. B. K2 A3 X) N2 C# x
  grid-y-inc               ;; the amount of patches in between two roads in the y direction
4 S3 A0 a  X' F: L  acceleration             ;; the constant that controls how much a car speeds up or slows down by if
! |4 D# X2 O0 V8 r+ j% d7 ^                           ;; it is to accelerate or decelerate8 u  N7 I9 S. C; f( G1 M& Q; \
  phase                    ;; keeps track of the phase
- v: Y, k" g8 L  num-cars-stopped         ;; the number of cars that are stopped during a single pass thru the go procedure/ S% l( B  |: u2 _/ b/ V' v2 x! \
  current-light            ;; the currently selected light$ d+ O7 f3 I, B7 K
4 `8 l! C2 N/ W/ }
  ;; patch agentsets2 h0 @! T) y! {4 t
  intersections ;; agentset containing the patches that are intersections% i8 J4 L' f; p, j' G2 |
  roads         ;; agentset containing the patches that are roads
/ f5 {" j6 V0 }  G% w]
! I6 W, {2 ?4 j9 U8 D( E6 a7 Y: f; p, \7 D- k
turtles-own% ~, {" m: l+ v% n4 D  x
[$ e, `7 P% U1 ^
  speed     ;; the speed of the turtle
2 U/ b! \6 F. N5 R. ]* u2 @& m! u  up-car?   ;; true if the turtle moves downwards and false if it moves to the right* v5 o5 ~. ?- c) _. g5 z$ ?
  wait-time ;; the amount of time since the last time a turtle has moved
7 D/ D/ L- P( p/ P) @" M]
( |$ c- ]* e+ b& J; I3 {/ W
9 S' w* A6 _7 e+ v5 z0 ipatches-own
% W; a$ Y4 j! Z; ~7 v" p5 |7 X[
0 W5 [* R8 }. S' q9 W  intersection?   ;; true if the patch is at the intersection of two roads+ o5 j9 w/ z3 l& |8 J! c/ |6 ~
  green-light-up? ;; true if the green light is above the intersection.  otherwise, false.# J! {( H* }* M) j4 B" P
                  ;; false for a non-intersection patches.
& X! A. }2 i! i( `1 A$ z/ o+ c' \  my-row          ;; the row of the intersection counting from the upper left corner of the, Y7 u. R* {* R2 u3 Q" Q
                  ;; world.  -1 for non-intersection patches.
+ N7 K% v/ F- C- M1 D  my-column       ;; the column of the intersection counting from the upper left corner of the
- s5 h9 a' q3 Z- W                  ;; world.  -1 for non-intersection patches.) C8 L8 i& M4 q4 c* v6 T
  my-phase        ;; the phase for the intersection.  -1 for non-intersection patches.) `* {# i; k5 `1 E
  auto?           ;; whether or not this intersection will switch automatically.
7 p  D( u5 z9 O& T9 Y* B; g" d                  ;; false for non-intersection patches.
) s) _  r% _9 ?$ U]3 H% x+ n$ z! A4 f0 i5 S
+ {- a$ D: x; N

7 ~+ S" d8 i4 l) y6 X$ R;;;;;;;;;;;;;;;;;;;;;;# ]+ F& C2 u5 |7 o4 a9 `% \$ @: T
;; Setup Procedures ;;+ R: y, }, q7 U6 ~
;;;;;;;;;;;;;;;;;;;;;;
9 T! X; F0 Y% A/ ^
1 ]; k3 z( J; _! s;; Initialize the display by giving the global and patch variables initial values.
# T* S9 Z! K3 `;; Create num-cars of turtles if there are enough road patches for one turtle to' ^/ [% ?- Z8 w3 g
;; be created per road patch. Set up the plots.% Q% o4 n' R% F. ^+ u
to setup; Z0 Q" {" {; B* [* w( e1 P
  ca! D- h; e, [$ o; p) \9 D; l
  setup-globals
9 N/ y, F3 P. t& }& U0 T) Z* |1 p: L8 P3 ?7 {3 F& ?4 f( X0 I
  ;; First we ask the patches to draw themselves and set up a few variables) L' y' ]/ C( W7 N6 g- X
  setup-patches) C; P+ Z5 a) R' l- z* X
  make-current one-of intersections, X9 k7 h* {! G0 W8 E
  label-current: N0 z* Y  t; |# N' D6 l" o
: G1 u- u' f. i7 e/ {" `9 y8 q
  set-default-shape turtles "car"; ]$ m( l' c7 D

8 F" F1 @3 T  [+ @9 |  if (num-cars > count roads)
: |3 N* l' I& T* H' B; A  [# e) H8 X* w1 f/ U, `: Z
    user-message (word "There are too many cars for the amount of "
4 N' ], U( D$ l8 ~  K4 A* k                       "road.  Either increase the amount of roads "% Y2 D) R5 n9 e  o( O! ~
                       "by increasing the GRID-SIZE-X or ", v9 [" L) U& Q
                       "GRID-SIZE-Y sliders, or decrease the "
* F4 F* u( s3 M2 v                       "number of cars by lowering the NUMBER slider.\n"
) ~2 H( F- u% o, ^                       "The setup has stopped.")* v  ~+ U4 k: P9 b5 l
    stop
) R0 A' ]3 v' n% `1 ^  ]( I+ W& Q( W7 {% B

5 |4 \9 h% D* m( S7 k  j) j% ^  ;; Now create the turtles and have each created turtle call the functions setup-cars and set-car-color
' C, Z: S. a% P! t  crt num-cars
" ~: }3 f( U; e8 K$ f8 q! b  [
5 s8 J4 D* Y5 X# p    setup-cars
2 M4 q( M9 c8 k. w+ _    set-car-color
0 n9 E/ B* r/ {2 c. U7 }3 J    record-data
1 y# v9 |# E4 q1 Y$ D  ]
0 V# C" b) }' N/ L7 L1 B$ h4 T
- x5 K; F1 j( z  ;; give the turtles an initial speed
# s% b  R, z. x& ?1 N  L$ D  ask turtles [ set-car-speed ]
# c  Y& p6 ?" F! T% _+ M' X. {/ t$ y- y, ^; M
  reset-ticks2 a% ?! Y$ Y: t8 @5 X
end$ X2 t& \5 D  i) X+ T* A
9 Y% [2 l. H5 K& v
;; Initialize the global variables to appropriate values3 I: U# S* }4 j7 F0 J7 e( o
to setup-globals( q, }% g8 R6 E( e5 u0 o. n6 l
  set current-light nobody ;; just for now, since there are no lights yet
: Y1 ^0 |: e6 v- l  set phase 02 m: {6 V& j% Y: z) @( y
  set num-cars-stopped 0
7 u% K; l  ^! V7 r  R: J; p  set grid-x-inc world-width / grid-size-x
: r0 J9 X/ i6 p1 X  set grid-y-inc world-height / grid-size-y5 k0 Y7 x/ Z2 T2 x! J7 ?' Q

, p& F) L8 U0 n  ;; don't make acceleration 0.1 since we could get a rounding error and end up on a patch boundary
) N2 M0 a' E( ^  x0 @: z  set acceleration 0.099
' D6 ^% J; p/ t+ g7 z/ ?end
' i3 B3 c3 P% b+ z1 g0 f
# d) _4 N& o. _;; Make the patches have appropriate colors, set up the roads and intersections agentsets,
; I% i5 m" Z/ E, };; and initialize the traffic lights to one setting
$ f, c/ P' g, H; N/ a0 ?to setup-patches" P1 @4 H; w, V5 t6 L
  ;; initialize the patch-owned variables and color the patches to a base-color. ]8 W1 Q/ x! b4 i0 t- K5 ~
  ask patches
, `* p0 e4 E2 [; R! z& f! Y; N5 K  [
9 V; n5 n7 V2 ?0 f  n" I- x& `6 m    set intersection? false
3 E& K5 [: U2 S  L% S5 \    set auto? false; E  L/ o# \  F  `5 N- A
    set green-light-up? true$ P+ S/ W/ Q5 V* o
    set my-row -11 N) c& b2 ]0 Y& n  W6 X' l( G
    set my-column -1% U$ m+ \8 s* C" {
    set my-phase -16 `; t, N: |! t3 f3 F
    set pcolor brown + 3# {2 c3 q+ Q7 P* I4 \& j
  ]2 p; |1 m3 l  k; w' M5 b- m
: n- T, p" ?4 ?7 j5 F) q. W2 }
  ;; initialize the global variables that hold patch agentsets# \! `$ w. I! ]
  set roads patches with; }4 k% n; G2 w% @, o4 O
    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) or1 P( N( w5 Q; C7 ~8 m2 w
    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]* z" t9 T6 H$ W! B
  set intersections roads with
: F/ Z' P+ J9 Y$ v9 q5 \' c, o    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) and
; U$ w9 q3 ^/ X    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]( h' D3 b9 {9 v: U2 e

" k9 Z4 C( a2 w* I1 v7 [* [, p  ask roads [ set pcolor white ]7 M% b: ]2 {! e& Z$ M$ P
    setup-intersections, t0 O2 P& ~) x3 j  k: {/ |
end: L. p8 C" ~8 t: i: B" {4 _
其中定义道路的句子,如下所示,是什么意思啊?3 B# G) C; y: @- O* s" t
set roads patches with
) {, ?; K/ @( [0 W    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) or1 c. u8 d5 m! {" M3 C
    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]
1 I' D2 f6 {6 G2 L! q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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