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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。2 ?3 E% C2 m/ Y" ]
netlogo自带的social science--traffic grid这一例子当中,
, T- b1 u( e* u+ d# e% J+ F0 Yglobals  F  o7 ?% c& Y9 K
[( s/ e6 {% \- u1 i
  grid-x-inc               ;; the amount of patches in between two roads in the x direction( _$ \+ Q& H/ W8 V- H. v
  grid-y-inc               ;; the amount of patches in between two roads in the y direction
: A  ~7 n3 P. d  acceleration             ;; the constant that controls how much a car speeds up or slows down by if
  K1 m, ?: @0 N" @% M: J                           ;; it is to accelerate or decelerate$ f; w+ w3 ^# |, o1 ]! H+ u
  phase                    ;; keeps track of the phase
- z$ f1 u& A' p  K% A6 S( W0 ~  num-cars-stopped         ;; the number of cars that are stopped during a single pass thru the go procedure& ~$ p& w, l9 ]" x+ L, n! |
  current-light            ;; the currently selected light+ G. \( u3 z3 g: ~

1 i) v% _" t& U. F, q: B$ O, ]* g  ;; patch agentsets+ p" a$ \* T$ [6 k
  intersections ;; agentset containing the patches that are intersections# w  \# y  c' d' f1 C+ e, j$ ~
  roads         ;; agentset containing the patches that are roads
+ `" U6 l2 I' j! L+ O]
3 B$ m, }- E# b
5 n% C% p( @! uturtles-own+ I- b% V, D! [( o5 F( D' N
[
3 V' ]; G) N4 T# A- j- U  |- l- F  speed     ;; the speed of the turtle
9 |: `5 c( B/ ~5 y  up-car?   ;; true if the turtle moves downwards and false if it moves to the right% a% A2 ]- u1 x, C6 T3 J7 ~* A9 D  o: D
  wait-time ;; the amount of time since the last time a turtle has moved& G- V# q; x! `/ V0 w
]) @% \0 n8 R/ N, Y/ H  B

* M/ }" L- \# zpatches-own0 z( J1 q! h# k: z: R* ]& R
[2 ]: ^0 E6 c8 }1 o3 x( H; X4 r
  intersection?   ;; true if the patch is at the intersection of two roads
: o( w, U7 q7 f) j, S* J  green-light-up? ;; true if the green light is above the intersection.  otherwise, false.
( X: G: i  C" ?& k2 d' f                  ;; false for a non-intersection patches.- f, ~1 V* e- h8 G, y! ?
  my-row          ;; the row of the intersection counting from the upper left corner of the
! _/ I5 }" L! ?5 x                  ;; world.  -1 for non-intersection patches.) [  m/ N6 g! x. r1 g
  my-column       ;; the column of the intersection counting from the upper left corner of the8 b; |7 G; H2 D8 _" `
                  ;; world.  -1 for non-intersection patches.
" D; o/ g3 Z3 H  Q+ l7 i  my-phase        ;; the phase for the intersection.  -1 for non-intersection patches.
" {6 y! b. T8 H7 A% _/ A/ E4 Z  auto?           ;; whether or not this intersection will switch automatically.
1 f3 }$ L3 U' F' A8 j/ U: N5 {                  ;; false for non-intersection patches.
+ `* d8 K* c  u) b, o$ N& y]
6 t$ V+ [4 u, w1 x" o  G2 W" T6 O+ r, B- F
3 c$ r4 h% X2 [0 t3 W2 [
;;;;;;;;;;;;;;;;;;;;;;, ^! R: T4 h( \# H3 ^/ X+ P- Q- @
;; Setup Procedures ;;
/ l" d% V/ P4 v  F  z;;;;;;;;;;;;;;;;;;;;;;. |$ Q: f+ R+ p. Q
% K+ l. H! J+ q2 D, I9 w* [! r+ ?
;; Initialize the display by giving the global and patch variables initial values.1 J) q+ L& ?! @- Q2 N3 h0 D
;; Create num-cars of turtles if there are enough road patches for one turtle to1 O1 Y5 @% a6 Q) `) B" s9 d
;; be created per road patch. Set up the plots.7 y, d- ^' [6 H6 B$ Y) R& i
to setup
9 G) t3 m7 u; W+ K6 z4 R  ca
& M6 z  a! T/ b$ n1 l  O  setup-globals
; S" K* x9 ^! x: a. i3 q2 n# ^4 w8 ~0 O6 ?4 b  a4 W2 \
  ;; First we ask the patches to draw themselves and set up a few variables9 e9 F" }' k' L/ {( ?
  setup-patches" e4 U: [7 k! j0 ^, H5 }5 Z; @. E. J
  make-current one-of intersections# ^5 S9 n; _3 C
  label-current* Z: z) g! {6 M3 }! y" H! m4 B% k! D
% U4 B7 x! @- S( A0 d9 p6 k/ ^
  set-default-shape turtles "car"8 [( G6 C2 R3 U

- [% T) H# E6 I2 u  if (num-cars > count roads): T( I' K( L  w; I( c5 f! h( E# Q) Y
  [
5 S7 [& g  M, b) u    user-message (word "There are too many cars for the amount of "
- |& K+ H5 v$ m. n/ _0 e                       "road.  Either increase the amount of roads "
9 l7 ~- L/ Y5 C- Y2 m# E                       "by increasing the GRID-SIZE-X or ". D, m; i: o& k: W( l4 l
                       "GRID-SIZE-Y sliders, or decrease the "# s  m2 L# Y; G1 c
                       "number of cars by lowering the NUMBER slider.\n". v6 B$ A. B; U3 B/ B, ]) P
                       "The setup has stopped.")
8 n* l5 a3 m, g( Y    stop
7 x5 s* Y# k  O' q" x  ]
# l* a8 J0 L5 B# w9 h2 r- S2 D! t1 V9 _/ w
  ;; Now create the turtles and have each created turtle call the functions setup-cars and set-car-color5 U  \3 T( w8 y% t$ x
  crt num-cars
' [8 N3 c8 }- g! z5 i6 K1 T# _8 z# D  [/ Q' w* z" d2 C7 w6 _# \0 ]
    setup-cars# k4 J' n4 _& w+ y. x9 o8 R
    set-car-color0 f  Z8 f' h9 s( W+ Q$ g
    record-data
0 p* v- z& O8 O" b& V. {0 k  ]
0 A# p! Q) T9 v. o4 C  S- A' F# @0 F
  ;; give the turtles an initial speed. e3 l- e$ i- [8 F5 Y; s0 f/ O
  ask turtles [ set-car-speed ]
0 L: z, o. t, J4 c9 x, h
1 X$ C7 w" b9 [% X3 Q& h1 [6 f  reset-ticks' j. O; f$ y( J/ U. |- Q" d
end4 E. v4 y; _* e0 z
0 K. D1 I/ o8 Q/ Y7 e4 Y2 Y
;; Initialize the global variables to appropriate values
/ W' E* g5 D; l* H9 jto setup-globals$ g# L$ Y/ S% f/ R) @9 l+ ]0 j* Z8 q
  set current-light nobody ;; just for now, since there are no lights yet
: R3 y1 g8 }+ H% J  set phase 0
/ a8 F) T/ I+ }$ H5 K( p  set num-cars-stopped 05 E  L6 F7 g' Y: n
  set grid-x-inc world-width / grid-size-x
; @2 ^- h4 k; Z, G$ R+ A  set grid-y-inc world-height / grid-size-y
; V" [1 }: h2 m- {7 [. v: N. O! l) ^4 q$ y$ \( P
  ;; don't make acceleration 0.1 since we could get a rounding error and end up on a patch boundary( j& v. v5 z& I% }3 P0 W( W' i
  set acceleration 0.099
: v3 v! l- t2 \1 f& ~3 F( n) A  U* nend
) H8 Q, T3 S2 `6 ?
3 K' O& C/ f0 T% O& f  j7 T* };; Make the patches have appropriate colors, set up the roads and intersections agentsets,
5 [5 M# z% E! ~: B4 P;; and initialize the traffic lights to one setting4 J/ W' p' y/ t5 Q. R% W& ^/ z% J
to setup-patches  b+ ^$ r0 N8 h; A; Z, m3 T
  ;; initialize the patch-owned variables and color the patches to a base-color
$ O. k7 s3 o( _  ask patches, P; _3 [, D% J
  [
7 M" C: T' Q" O, x( t) L4 b    set intersection? false
/ x3 y6 e6 l" C    set auto? false0 N- n. I; P; W: r) u7 l, h
    set green-light-up? true( X" y! p- a+ {6 @
    set my-row -1
7 K: z! [* g& P( p" l+ c# }9 Y    set my-column -1) G; J' B; u! K& o. S% h
    set my-phase -1
# H2 n$ W5 {8 H+ X) J; `2 v    set pcolor brown + 3* n9 X) a2 {# X9 ^3 X! K$ l
  ]
! X/ Y7 c. d& c. ~
0 X8 N9 A: F4 U( W( N  ;; initialize the global variables that hold patch agentsets
7 b+ p* b1 ^3 Z1 q$ f  set roads patches with
# ^. l2 ?  H0 ?, N% C: {    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) or
' F0 W" u7 O( Q$ q* C  i    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]2 G% E6 f. u  F  C4 F- Y7 Q/ ^& ^
  set intersections roads with
( q2 q' r3 h* z/ l' `7 }    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) and3 d  n# r' _6 O/ U- x  t$ x
    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]2 p" n- y1 ]% d) z
$ e* b( [" T) d: V3 [- M7 N
  ask roads [ set pcolor white ]
, e0 Y! `6 e( S" S" @4 w6 A% J    setup-intersections
7 I) W' p& |( H: h. Lend
- l, L+ U  B  J4 @. v其中定义道路的句子,如下所示,是什么意思啊?
3 [7 s+ _9 F# L4 P" m8 r set roads patches with4 V8 n  q' A1 s, R9 K! p4 M
    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) or
1 |  m! s! x5 i& c    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]
( ]4 V; p0 X1 }+ M1 z/ a% y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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