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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。  h2 s/ H2 L! T1 T
netlogo自带的social science--traffic grid这一例子当中,
9 M" a9 l, i8 e2 V0 jglobals
4 J% D( w$ y4 r% [: M* U[) l7 D& P3 @( w( V/ v
  grid-x-inc               ;; the amount of patches in between two roads in the x direction" S! }9 d* D. O' N! ^$ H, r3 x
  grid-y-inc               ;; the amount of patches in between two roads in the y direction
: F$ x" [0 [0 r  \% f, j' n/ w; @  acceleration             ;; the constant that controls how much a car speeds up or slows down by if5 q- a1 c; g* X. `+ k# q4 A
                           ;; it is to accelerate or decelerate+ ?- n' q% L8 l( C- X
  phase                    ;; keeps track of the phase
+ U  O' w7 r+ \( j  num-cars-stopped         ;; the number of cars that are stopped during a single pass thru the go procedure
  S  J) I7 `6 {, S# Y  current-light            ;; the currently selected light
' a3 z: r! A# M" e4 {3 |5 R# s) B! }. E0 n! {3 y5 J
  ;; patch agentsets8 s4 j9 M! \& h
  intersections ;; agentset containing the patches that are intersections  x$ v, k) j. C' y' m8 E
  roads         ;; agentset containing the patches that are roads$ _6 v! F; F2 g& K" B0 t) F
]
9 }( @" P4 \3 D, x
; @  ]6 N5 A- c$ `- rturtles-own
2 i% i, R; P$ {) Z) X[
* i" r2 _  m& B* ^) x, C  speed     ;; the speed of the turtle
/ S& V# i- ^' j* y! I( c  up-car?   ;; true if the turtle moves downwards and false if it moves to the right+ c, U6 s1 x. |4 |* \4 {/ E
  wait-time ;; the amount of time since the last time a turtle has moved
9 T' R2 F- Z# }( w- l8 U+ k]6 m0 O6 _& m- I" }

# J" {- l  _% {0 q7 i; Mpatches-own
$ C  T3 w9 K% J% Q[" `$ T5 E' o0 _
  intersection?   ;; true if the patch is at the intersection of two roads. \# H( l) K, y  q4 D. V1 V9 j
  green-light-up? ;; true if the green light is above the intersection.  otherwise, false.
% r  r7 [( Q6 M3 H                  ;; false for a non-intersection patches.  d( ]' Z. K# [$ s
  my-row          ;; the row of the intersection counting from the upper left corner of the
6 w. @5 R. o$ d6 H8 F- B" y( I3 g; o1 R                  ;; world.  -1 for non-intersection patches.( i# I7 X1 M" L4 e: S/ z6 t
  my-column       ;; the column of the intersection counting from the upper left corner of the4 K' M: j$ Z" V4 h, O1 c" z' {
                  ;; world.  -1 for non-intersection patches.3 ^+ F; o1 E# S* b" x2 A, @$ r
  my-phase        ;; the phase for the intersection.  -1 for non-intersection patches.1 J( D3 N* X5 u& S  @& T7 o4 e- A
  auto?           ;; whether or not this intersection will switch automatically.
4 G+ o7 V  j, J0 J* B                  ;; false for non-intersection patches.! n# o3 W% _/ b# G' Q1 N2 k' O, I7 ]
]
  a% N: Q1 O" K. Q0 ^7 E; o' V' u* J% ?! a$ e" W' D' z
* l6 }2 `. P  d2 G/ y" A7 `
;;;;;;;;;;;;;;;;;;;;;;
9 c  i0 e+ Q- {;; Setup Procedures ;;) k! B( Z% B9 {( C
;;;;;;;;;;;;;;;;;;;;;;3 \" q. h1 ^  P$ p8 i" X

+ s* _8 b# f- A* x% M* t4 W( A, P/ D0 X;; Initialize the display by giving the global and patch variables initial values.
/ I& z% [% Z$ p+ {;; Create num-cars of turtles if there are enough road patches for one turtle to
5 x. j8 @& J# S, m;; be created per road patch. Set up the plots.
* l) Q" Y, ?* \/ Z6 [; lto setup( @/ j( f* i7 Z4 c
  ca
( V" E, l  I- Y* L" W0 m  setup-globals  g. U; x* C& i8 G3 A5 e

- Y0 P$ }$ d4 Z& V5 U8 E4 @  ;; First we ask the patches to draw themselves and set up a few variables! s! [' q- F8 d
  setup-patches$ ?. R" ~6 z: x. o7 P8 A
  make-current one-of intersections
4 V- D4 e1 e& L" P: _9 }4 c$ Y% H  label-current
+ X( D% _  P0 U6 h" N
3 c: |( V7 l/ Q# i& e* j5 {& @  set-default-shape turtles "car"
/ D% v: k) ^) l- M& f/ ?, j( W% K
  if (num-cars > count roads)6 Z9 @3 [$ j1 p/ ?1 c2 v/ K* J
  [
& k' a' I7 g! v% [* Q    user-message (word "There are too many cars for the amount of "  S7 z! H5 X0 Z4 Y/ o1 u
                       "road.  Either increase the amount of roads "
1 z' P! x4 X: ]) Y! _                       "by increasing the GRID-SIZE-X or "& t! {+ O9 v1 h3 ?$ C/ o: G
                       "GRID-SIZE-Y sliders, or decrease the "6 i1 y1 f+ r5 }* w
                       "number of cars by lowering the NUMBER slider.\n"
! I9 {4 \! s: p                       "The setup has stopped.")
) d1 J- o" T# E2 e& u( ?    stop
  Z0 o( D( [& Y1 G$ F  ]' {  [: `% K$ }( Q( f

; @' n* P3 S4 o3 T# v  ;; Now create the turtles and have each created turtle call the functions setup-cars and set-car-color7 I, R, C: ^' S9 T) a' p) `+ Z
  crt num-cars- M8 W2 _) c/ z; K% F! G
  [* e& m+ W% ^, S3 g/ [% q
    setup-cars/ Y4 j% V. u% W. A. |
    set-car-color
% Q8 A) P: Q$ f  z; D    record-data
( I$ @  e) i0 Y0 V  ]+ R* C( ^- [2 Z" K" j4 W5 M

" ]* E  t$ }5 r  U; ]/ D  ;; give the turtles an initial speed9 V( \6 D3 t! A) ~6 y( s
  ask turtles [ set-car-speed ]2 X/ C1 H1 C' X: f' g  U2 F5 G

9 o# h5 u/ U  K& |2 P  reset-ticks  O1 k$ G+ R' _0 z, x9 h
end! J( f4 m; x, w2 }) m" Y

% _, Z8 S8 t6 M4 y/ d7 G" {;; Initialize the global variables to appropriate values% `( P& n; t( e# H9 Q2 n2 C9 X
to setup-globals. S% F- _' s! k" c( c* b
  set current-light nobody ;; just for now, since there are no lights yet' B, {3 _& s; \' @- e4 N' n: y+ Q
  set phase 0
4 S; j6 g; X1 z5 K' |# `5 {  set num-cars-stopped 0
( O2 q. e  Q) _2 [4 B4 Z  set grid-x-inc world-width / grid-size-x
2 @( U/ Q( R  M4 o5 I  set grid-y-inc world-height / grid-size-y
) w( j5 @+ u' w
% R5 i' L1 h, z8 c7 v' M  _  ;; don't make acceleration 0.1 since we could get a rounding error and end up on a patch boundary
. @# C" i, x" O; {. l" M4 Z) r  set acceleration 0.099* Z- u: A% [. u# f( L
end$ M+ j3 D: {. q
( J$ Y5 ^6 v1 i6 }+ y1 _
;; Make the patches have appropriate colors, set up the roads and intersections agentsets,
3 ]: q$ z: d0 d;; and initialize the traffic lights to one setting
: Y+ V7 ]( ]2 }9 P3 jto setup-patches1 ?" S! w. f6 @& `/ v) J4 s
  ;; initialize the patch-owned variables and color the patches to a base-color
  e6 u% h, v9 S, `1 i7 N/ {! V  ask patches2 O/ K! h. N$ g2 {
  [2 ~* C+ r6 t$ v# F
    set intersection? false4 g( p& T7 F* D0 v
    set auto? false
4 H; V5 H0 Q6 Z3 S* e4 T# ]" }3 g    set green-light-up? true
" a" N6 R) j; B1 {- d- _+ B    set my-row -1" Z8 f  S5 F# b. B2 D
    set my-column -1' l8 m& Q; b3 Z/ A3 E! b  V: X, Z
    set my-phase -14 c# b5 e2 L, }) U5 v
    set pcolor brown + 3. v" g: y; G7 K2 N4 h# p9 ]
  ]* ]  h' F; l3 G  y+ `0 x# T

) V5 ~; V9 E' g+ t. H  ;; initialize the global variables that hold patch agentsets
/ |8 I5 S5 m8 T6 z/ l  set roads patches with7 [! A/ i9 K" |. X
    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) or. `: h; T& \% c
    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]
: R% y1 n# ]$ V  S, b% |& R  set intersections roads with/ w; ?" s; j" E2 f# E% Z
    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) and
. v! `' R# e  B, y+ }+ N    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]) _' c0 S; [- }! n

" x+ r" ]% h7 c& w# V3 ]  ask roads [ set pcolor white ]
8 \$ j) D( T- s: \% r    setup-intersections3 G& p4 y: [9 L
end/ ^( @+ Z; L# M8 G# K4 K. I
其中定义道路的句子,如下所示,是什么意思啊?( ^( S& T2 z- o; D2 P$ r
set roads patches with
8 y% y5 e/ I  n+ x- `" G+ e    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) or
; i* r( a6 z; \' h6 l    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]' g, R) l* x) t# 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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