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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。
# U( P0 g6 k- l* L7 F( Cnetlogo自带的social science--traffic grid这一例子当中,+ N: Q6 H; C/ [! I' ?
globals
7 F' }' l) Y/ ?[
% v8 H# n5 m3 B& x  grid-x-inc               ;; the amount of patches in between two roads in the x direction2 v  n) u& g8 u; r
  grid-y-inc               ;; the amount of patches in between two roads in the y direction1 g2 @7 T! h% i/ S+ u1 ?
  acceleration             ;; the constant that controls how much a car speeds up or slows down by if) `% d0 r8 [3 C5 o
                           ;; it is to accelerate or decelerate5 ~+ ?4 ^0 j; }% l( L9 y/ |6 e! d5 F+ K
  phase                    ;; keeps track of the phase) |9 @2 S) y, m  {0 ?5 J$ n
  num-cars-stopped         ;; the number of cars that are stopped during a single pass thru the go procedure" a* u& f9 t# o
  current-light            ;; the currently selected light
0 m4 F; ^8 y- Z' n& e8 K2 S6 s  R5 _& k* X& c8 C( w
  ;; patch agentsets
, \* |  T$ y7 N  B  intersections ;; agentset containing the patches that are intersections
7 j4 Q7 ?( r2 ~+ P) e8 ~, I! u+ a$ r  roads         ;; agentset containing the patches that are roads: u. c2 D6 V1 ~: C9 n1 i( P6 u
]9 y$ D1 R1 f% ^; T
# i2 G# f, N9 U" {/ i9 k2 @
turtles-own
. \! y# q8 t, d, S' |0 w+ ?[$ \5 F& c8 }5 O) o
  speed     ;; the speed of the turtle8 \# @8 _, a; z( H/ ~
  up-car?   ;; true if the turtle moves downwards and false if it moves to the right5 K. w+ h8 Z1 O4 L+ L0 K% Q' }
  wait-time ;; the amount of time since the last time a turtle has moved
! f: t8 q( `/ y2 N8 l. c]
  a: u- }" j! U8 ^) f9 c! T2 R' e, @! |& Q4 l4 x
patches-own6 \% f$ L$ ]! G  g% C. V7 |: }
[
- ^. }! [: T  {2 _" m* }$ U  o+ [7 }. ]  intersection?   ;; true if the patch is at the intersection of two roads* E  u) d$ z* U6 Y8 k' z
  green-light-up? ;; true if the green light is above the intersection.  otherwise, false.: u; B' `7 P7 A$ J# s) y
                  ;; false for a non-intersection patches.
+ Q: p- R6 z) T% @& b% r7 X8 o  my-row          ;; the row of the intersection counting from the upper left corner of the
0 ~! K' `2 L" w! j                  ;; world.  -1 for non-intersection patches.
0 {* s) a2 x. q* S$ l* h  my-column       ;; the column of the intersection counting from the upper left corner of the8 n* T9 f( C: L3 _; ^
                  ;; world.  -1 for non-intersection patches.* _; \: `: e6 A; M) Y+ w# \
  my-phase        ;; the phase for the intersection.  -1 for non-intersection patches.
/ Z+ ?3 a; V1 v. p0 G& E  auto?           ;; whether or not this intersection will switch automatically.
# k) o1 G* ^& l0 e2 ~& _                  ;; false for non-intersection patches./ E7 h( [! T; ]- G  O
]6 p# l3 u  @7 k7 f' l0 K" g2 y

: a- N) @9 j9 v6 T* e" r
0 b" I1 [0 b% l+ O;;;;;;;;;;;;;;;;;;;;;;1 r% e5 ~  I. V: E9 e) N
;; Setup Procedures ;;9 t8 v, }6 L9 e3 t: I, I. M
;;;;;;;;;;;;;;;;;;;;;;% h2 p: C+ p) a( n4 H; e

. Y: K5 U, J* d6 ^  g( ~" D2 l;; Initialize the display by giving the global and patch variables initial values.
6 t- f! n- e1 c;; Create num-cars of turtles if there are enough road patches for one turtle to
& z5 s2 [4 P$ B" o+ B0 N;; be created per road patch. Set up the plots.
& f; j$ o! d5 R  E3 kto setup9 }0 G7 j3 P! a8 S3 {: [0 T' Y
  ca
1 y1 f5 K5 P. w) R- ~* t  setup-globals8 `' d* q) N' }' J2 V& w4 c
. u) `, k, j0 c9 F4 F7 m
  ;; First we ask the patches to draw themselves and set up a few variables
6 M5 ]4 D) Y( w$ |: `9 P  setup-patches
% C% ?- h1 |6 b0 ?9 `' h  make-current one-of intersections
$ S( B8 N6 t$ z+ p! B4 V  label-current
8 K" n9 W$ ]" N5 w# W) y* P( \0 F9 }( r
  set-default-shape turtles "car"% C* O; a( N5 d" L
$ A) A' k, X' V/ ]
  if (num-cars > count roads)
; _5 i  O9 m4 S1 Q8 R  [  R- F* S+ K% h
    user-message (word "There are too many cars for the amount of "
( V' c8 m0 V6 W                       "road.  Either increase the amount of roads "
6 U. ]) K( ?: r: A+ K) f                       "by increasing the GRID-SIZE-X or "
) }- m0 D( v3 U( N. D) z4 {                       "GRID-SIZE-Y sliders, or decrease the ", j6 i, g8 E4 }8 V- X. ^
                       "number of cars by lowering the NUMBER slider.\n"
# F* u+ `' }# f5 X: O4 i+ o- Y                       "The setup has stopped.")
- Z5 T; B" l9 y0 o9 O7 l    stop
$ s& v2 O6 A! {, Q  O/ x4 ~  ]
$ b# {1 r  O& ^$ N3 ^
) D9 n/ [. d- r0 i1 B& x7 y0 ]* v$ v  ;; Now create the turtles and have each created turtle call the functions setup-cars and set-car-color5 m+ L% @: I3 ]
  crt num-cars
8 Z3 d# `! N  b; J# B6 Q( X  [6 B" ?/ q/ {9 @0 `% f  Z+ G
    setup-cars
- V: ?" D4 V5 X8 e& d( X    set-car-color5 C' f6 U' b; K4 _
    record-data
+ D! u: D- d; N2 Y8 Y+ c8 M  ]
' r( i: l8 H( Y! @1 {! G+ k
: G- a  U) _' [6 w: s  ;; give the turtles an initial speed8 g+ J* D5 X6 L. u) x4 r
  ask turtles [ set-car-speed ]* e$ ?" i/ p1 W/ R8 C9 `

# h* ^* o" r1 Z" |3 q4 w: ~* m9 q  reset-ticks3 k& p& C( A5 c5 e# ]7 O
end
0 C) X0 O, W; }/ m
) v( K" p9 o! @4 P( r4 o) c;; Initialize the global variables to appropriate values
6 `8 e! t7 F' i8 ~8 c) Yto setup-globals& }* Q' d( O+ U5 n5 P
  set current-light nobody ;; just for now, since there are no lights yet
6 X4 j# g6 |( w8 r: a" S  set phase 0
& r1 e7 s: G% d; x9 T  set num-cars-stopped 0
- Z) [) t$ q, Q6 c& c1 B  set grid-x-inc world-width / grid-size-x
1 L: r; g, E" p: y7 T& v  set grid-y-inc world-height / grid-size-y! k7 T% \9 s. ~( \5 a

9 A" F1 g; H% B8 ], c, I, B+ T  ;; don't make acceleration 0.1 since we could get a rounding error and end up on a patch boundary5 q* \4 N9 ^9 I1 q) y1 P
  set acceleration 0.099: i; G: Y, d6 ~+ p" `& w6 i# d
end
# w1 T9 t+ P$ D5 z) m- ~1 |$ p$ e  {" O' y6 h2 \4 U* `: G
;; Make the patches have appropriate colors, set up the roads and intersections agentsets,
: u) H" D2 m/ c' f) P;; and initialize the traffic lights to one setting" K2 I. g: ]( R$ e+ d
to setup-patches
2 ^& W' `8 [& L% a0 E% u! p! l; h  ;; initialize the patch-owned variables and color the patches to a base-color% m% T5 \7 T- X1 |/ T9 M  X. Z
  ask patches; ]$ r  H  `( b9 Y) N# n
  [
; K4 S9 \2 g7 X8 T$ d" W) }    set intersection? false
; b3 v' j5 g% W! X$ n- R5 I# L    set auto? false" j0 R8 @7 N% l8 W$ i6 a$ \& P
    set green-light-up? true; n# E7 S; `# k' G4 m
    set my-row -1
4 ]8 u5 P# y4 U# {1 B4 J    set my-column -1/ V2 [: X, V+ Z- r- f
    set my-phase -1
, Z  X/ ~5 e5 Y3 i2 |' N, _( Q    set pcolor brown + 35 u6 I9 L0 L' v' V* c+ S( y; H
  ]6 O" h9 ?3 T# E+ f: w' P

* Q, y# M$ q2 h8 C$ P  ;; initialize the global variables that hold patch agentsets
  o7 d' A3 C* k0 `( I  set roads patches with$ W5 V7 ~4 F3 {: a( O
    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) or
/ c3 s' S% E, H$ J. V    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]+ }1 @$ R1 E4 y- o
  set intersections roads with9 s( b  o: B# B
    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) and3 h9 j3 w& D8 B" j7 H! y: p) ~
    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]
* n' R8 \6 {& j3 G% R* B$ ?% P, ~1 n# D3 j
  ask roads [ set pcolor white ]; m$ _( ]( M% W4 ^
    setup-intersections( l' f+ F" R. F9 S" p7 v( B, x
end
" R$ ^5 _) ^" r其中定义道路的句子,如下所示,是什么意思啊?
9 \& Y* ]0 T& I  h set roads patches with  j. S1 I+ a0 P1 x8 S
    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) or" X3 Q: s) R& R% ~
    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]" {' Q- f. h. \2 r
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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