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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。+ q. S. Z$ ^( d
netlogo自带的social science--traffic grid这一例子当中,
6 k/ s, u& t& c) Rglobals
4 i$ _  i6 F* H: \. l, }[
: m( U( E& r& M( W2 G  grid-x-inc               ;; the amount of patches in between two roads in the x direction$ U. e) A# e* x% ?) l
  grid-y-inc               ;; the amount of patches in between two roads in the y direction
, s' N! n* b0 s1 e  acceleration             ;; the constant that controls how much a car speeds up or slows down by if  [8 M* h7 c4 P+ n
                           ;; it is to accelerate or decelerate
6 J: X! h. H. [' |  phase                    ;; keeps track of the phase
4 J1 b& X2 n& |& X3 d" [* A  num-cars-stopped         ;; the number of cars that are stopped during a single pass thru the go procedure
5 e; U0 \! k4 R( B/ _  current-light            ;; the currently selected light
% z( ~5 G- F4 H1 H/ F1 y1 o7 S% g! ?; a% X! U- G( c+ B1 e
  ;; patch agentsets; \) L% F9 a* I2 u* w+ a% e
  intersections ;; agentset containing the patches that are intersections
( t- @2 B1 x. x9 I! i) W; t, p6 I! s  roads         ;; agentset containing the patches that are roads
, ~. D% }& w" A0 h; ?+ B0 C! P]
) ^; d" l% X" x$ G- |0 ~8 {9 m& ?; U3 m/ d' J3 ?4 ~6 {
turtles-own
* E6 {/ ~$ G+ H; v[0 H9 ^4 i! Q# G5 W* C8 J6 e. K
  speed     ;; the speed of the turtle7 l8 O+ _8 W" J  o; @
  up-car?   ;; true if the turtle moves downwards and false if it moves to the right
  [( S* c9 Q9 ?  wait-time ;; the amount of time since the last time a turtle has moved
$ b" N1 f- ^" D0 g]; d& f% ^0 }* T
/ N3 S" r$ w& E2 u& ]" {
patches-own
9 q9 C' I- W8 L  L- R/ C# L( }[
" J1 F+ |) d7 M1 X% d4 J& n  N  intersection?   ;; true if the patch is at the intersection of two roads" p( k) }) |& O
  green-light-up? ;; true if the green light is above the intersection.  otherwise, false.; U# e, z" k+ e& o0 |  J# ?
                  ;; false for a non-intersection patches.# F3 g8 E4 e% g' N  u0 e8 h6 G
  my-row          ;; the row of the intersection counting from the upper left corner of the
3 R) I# }3 f& f  @3 `                  ;; world.  -1 for non-intersection patches.3 p& M: G, W7 u9 K" ^/ [7 }% A. N
  my-column       ;; the column of the intersection counting from the upper left corner of the
+ _- i: e& H' ]& ]( C                  ;; world.  -1 for non-intersection patches.
% ^. s* B. i5 l  g/ O) j. ^" _9 ]  my-phase        ;; the phase for the intersection.  -1 for non-intersection patches.
& ^6 \8 T1 A$ y! q; e2 k  auto?           ;; whether or not this intersection will switch automatically.
8 q% @% w  ^7 W9 D# C6 b                  ;; false for non-intersection patches., I! f% m2 I: E
]4 @8 y1 D8 j1 h- D3 K9 W

5 k2 R& Q0 G9 x" k4 h
' @! I6 Y5 U) [;;;;;;;;;;;;;;;;;;;;;;
, {9 B9 f0 r1 K5 b: r! D% I, w- y7 j;; Setup Procedures ;;
$ q9 z2 e% m7 ?3 R0 }! K;;;;;;;;;;;;;;;;;;;;;;
9 W! G5 j+ o" v0 Q* ~9 q! \" y: D$ p  `  a8 c7 |: ^
;; Initialize the display by giving the global and patch variables initial values.3 [( O; K' P. A" n, O( @$ u
;; Create num-cars of turtles if there are enough road patches for one turtle to
% p! Y6 _- N# ]6 u: _;; be created per road patch. Set up the plots.( G: e) M: s% C* R, X8 B
to setup' x- j. X) s( S+ X' w# {, m
  ca) t. d/ L8 X7 |9 R# x
  setup-globals
8 O, I5 T6 H) t3 w' p6 {# J: i  V# V: y4 c+ [: r
  ;; First we ask the patches to draw themselves and set up a few variables; P2 k( a# M$ k' V3 D: Q
  setup-patches
) o5 q$ O5 n/ X7 Q" G  make-current one-of intersections
7 y6 k1 O0 ]5 R+ `+ P  [& k  label-current2 |" @8 E- u; U

; x( U9 V* \( M; H- V  set-default-shape turtles "car"/ G0 X7 M3 W: w7 y* m5 w3 ?
3 u) z2 [+ B5 Q, h4 q5 X
  if (num-cars > count roads)* P5 g" Z7 G& j  B! M4 P3 p
  [
8 ?) U, N: P! U6 U5 w/ @    user-message (word "There are too many cars for the amount of "8 K2 W& L/ B7 ^% K9 H
                       "road.  Either increase the amount of roads "
: i0 h  q! S( Y; X' _                       "by increasing the GRID-SIZE-X or "
8 {$ f3 a. v3 w% d( [+ `                       "GRID-SIZE-Y sliders, or decrease the "' K. ~; l$ x) A+ C9 L
                       "number of cars by lowering the NUMBER slider.\n"
4 N) q, ^3 Y+ t' l                       "The setup has stopped.")
2 x1 ^$ B# _% h) a    stop1 c3 h+ a+ z; V  I. X. C3 P
  ]
/ @4 H  B: K; q! F) H" A9 Z8 P* P5 j' [& K- l$ [
  ;; Now create the turtles and have each created turtle call the functions setup-cars and set-car-color' O4 K2 h) B+ N' v
  crt num-cars  w' \$ h3 g% ]; A
  [
& o8 B0 O9 }  J/ T1 R- a7 G' I, T    setup-cars" |& k. o$ Y( C- \9 n
    set-car-color
# N$ `" x$ Q1 A' ]    record-data, O9 C# O$ u+ D! s* }6 [' U
  ]. L# Q' a8 n: C4 [" g3 K( ^% @1 s
0 m# b1 R4 M1 u# |, Q8 A( ?
  ;; give the turtles an initial speed
. L6 J9 i. r( ^  ask turtles [ set-car-speed ]8 H; z3 L1 Z+ ~: p
- T/ a( y) g" O* q
  reset-ticks
7 K! I7 [& x( _end' B$ P: p) @) n9 [% e5 {

% x: e# V% E4 ^, P;; Initialize the global variables to appropriate values
; p$ B; t: B3 q) n) H; xto setup-globals
) _9 u0 t/ o0 D  set current-light nobody ;; just for now, since there are no lights yet
/ }: i6 U5 j& x, i" {8 @6 q* c  [1 i  set phase 0
1 e4 Y0 ^1 ?) b4 [$ q  set num-cars-stopped 01 w5 f. u7 H- W' @2 _: s
  set grid-x-inc world-width / grid-size-x
" @$ o# {- Y+ H7 D  set grid-y-inc world-height / grid-size-y* r9 D# x3 m3 |/ y1 T! G
! Q' n/ d5 f' C, c3 h  H+ {" Y
  ;; don't make acceleration 0.1 since we could get a rounding error and end up on a patch boundary( P) A* i( [* b& l8 v
  set acceleration 0.099( p# N% N1 m8 a
end
) {3 s1 V- W. D0 @$ p, r6 u) m0 X9 u
& k0 u1 l6 A8 O: @' n& ];; Make the patches have appropriate colors, set up the roads and intersections agentsets,
$ z. ?/ {# |' R5 i, v;; and initialize the traffic lights to one setting
: e+ n" p# e, R) ^to setup-patches) A* b2 t0 f) f4 j
  ;; initialize the patch-owned variables and color the patches to a base-color$ N& ^5 U( Q7 v/ v2 W; d) T! [
  ask patches
1 d9 m  X( i& @7 F0 x4 |  [) g8 l, [2 f- n- w
    set intersection? false
. k+ Q1 V: i* ~, l. D' x    set auto? false
2 z* e, G# }" J+ A! S' ?  R% p    set green-light-up? true
% O' t6 f7 `3 o    set my-row -1
  C' q# V  W5 f5 m* v4 r5 h    set my-column -1
( T! i6 K! `2 o  M- a" i, `; [& {    set my-phase -1
% O4 d4 }0 D2 O! e( I    set pcolor brown + 3/ Q: v/ V, a2 [: S' C: u
  ]
4 z( ]' Q& V4 `. x, j8 k- ?, |7 F+ [7 x! v6 d9 x
  ;; initialize the global variables that hold patch agentsets9 H! i& Z) F5 f: Q2 P+ u8 _  T
  set roads patches with# C6 `: O# t0 t! M: q
    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) or% l) P) B. n1 d1 d- p
    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]
+ \8 U. ]3 G  E* F3 U2 n1 S- I  set intersections roads with
- G( V( ]% X4 |5 ^9 ]    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) and$ q% w6 z% J9 }" k
    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]
! U; y2 ~1 i. m% ^- m9 C
) |2 [* x, Z( A# l& ?& _  ask roads [ set pcolor white ]
/ ^6 _! M. b! z( [! [: I    setup-intersections
, y4 Q. d; w: z# i, j5 u  a" N, P: cend# N" w: q9 ?9 l( q/ M
其中定义道路的句子,如下所示,是什么意思啊?
; \8 }# r4 B  n1 H7 c/ p- _ set roads patches with
: y6 g, Z7 r) w$ @7 x2 w8 @    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) or
! s8 k6 X4 |3 v2 X5 I0 C    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]
5 i, v2 S+ ]5 @8 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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