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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。
9 K% D( i. |- C# C3 Rnetlogo自带的social science--traffic grid这一例子当中,
: P, j  p' g6 Y1 g7 ]% Kglobals  W, A$ ?$ U: F: J
[7 D% }9 u0 f3 u6 W
  grid-x-inc               ;; the amount of patches in between two roads in the x direction6 p$ M/ M1 P, R( Z3 B/ d) B
  grid-y-inc               ;; the amount of patches in between two roads in the y direction
* a, T& V) T/ N  acceleration             ;; the constant that controls how much a car speeds up or slows down by if
# H$ R% I: p! W4 ]9 d* O+ d                           ;; it is to accelerate or decelerate6 W( g) g% }* u) ]
  phase                    ;; keeps track of the phase$ z! L5 J9 o5 R4 g  H0 s# ]
  num-cars-stopped         ;; the number of cars that are stopped during a single pass thru the go procedure
; M( U  h( v! p  current-light            ;; the currently selected light8 i9 P. z6 @& N5 L

1 e9 {7 {* {; d# x% w% v  ;; patch agentsets/ S6 ?4 g  ~8 t$ y1 |' m" j* z2 U. S; N
  intersections ;; agentset containing the patches that are intersections
6 h0 T$ C( C8 f  roads         ;; agentset containing the patches that are roads
' z( {0 _: N, R) H8 Z# l3 f9 p]
/ L0 o* \6 V# Z& @  C+ a" O5 h2 D/ P  l6 ^! U
turtles-own4 q' _/ L' _5 f: [& `) p2 R1 K
[6 c. C. ]% t, ^9 C8 m" E
  speed     ;; the speed of the turtle
( q: ]5 n7 _. w  @" V  up-car?   ;; true if the turtle moves downwards and false if it moves to the right) h: s( e9 K# T4 S
  wait-time ;; the amount of time since the last time a turtle has moved
; ^- S3 J1 n# g4 p! v% A- [. O]: l& ^! c% S# k# k; z" g

6 ?: _  M! `& g* Bpatches-own4 s5 c4 Y% S6 I9 T
[5 ?& V, U' A' [6 B6 l6 y' w9 N& ?
  intersection?   ;; true if the patch is at the intersection of two roads
2 [, w7 R- b, s* l' Y3 C  green-light-up? ;; true if the green light is above the intersection.  otherwise, false.' E* A) g* ?& ?9 i
                  ;; false for a non-intersection patches.
) k) m' ]3 V+ I* c- w  my-row          ;; the row of the intersection counting from the upper left corner of the/ B8 |+ o7 q& E# I1 n4 p
                  ;; world.  -1 for non-intersection patches.
% W4 ~9 T" L4 T6 r! V0 \7 R7 p  my-column       ;; the column of the intersection counting from the upper left corner of the% Z8 }# c9 k' [4 {! s9 d
                  ;; world.  -1 for non-intersection patches.( C% v7 Z* B4 ?" Z- b
  my-phase        ;; the phase for the intersection.  -1 for non-intersection patches.
; U( @7 g& P* r2 Y  auto?           ;; whether or not this intersection will switch automatically.
1 }) d3 ~5 q3 }  I2 k                  ;; false for non-intersection patches.7 r9 g" ]) Z9 ?1 J0 w, Q; p0 I- }
]
; ]* y- z5 h5 B' z: Q$ [( D& G, J" D2 H& T0 N9 `2 W0 K/ k

0 h* b$ \5 }& x;;;;;;;;;;;;;;;;;;;;;;
) ?  J2 X$ k, ~5 W( ^  T% p;; Setup Procedures ;;: w9 v. U+ ]; o$ q: e2 D' }
;;;;;;;;;;;;;;;;;;;;;;$ y1 d8 U0 |' j; H0 h" ~5 h

5 c& S; [3 ~" |  G6 `7 q$ u;; Initialize the display by giving the global and patch variables initial values.  I# g/ Z* p, u$ ]  d
;; Create num-cars of turtles if there are enough road patches for one turtle to
4 e9 h4 j' v' y; I' i8 U;; be created per road patch. Set up the plots.
) }. B8 T7 \0 Gto setup; E9 S0 J3 a5 D6 ?9 S4 b$ M
  ca2 T% p; ?$ F' Y# H/ l5 e8 c
  setup-globals* e/ J8 j2 L0 t5 S6 ^
5 v( B" F+ t5 G* [1 W
  ;; First we ask the patches to draw themselves and set up a few variables8 t; m7 _2 s, t" L
  setup-patches
$ c5 `% {  O! ]6 N4 l, E! ~  make-current one-of intersections8 B' J& A6 L- z) D2 J
  label-current
, P: N/ T& v! C; u, \
% r* b2 E  V5 I) F8 w  set-default-shape turtles "car"  s4 @. H/ ]$ j( |

5 J- U# i5 q+ {2 p( `( z  if (num-cars > count roads)9 a, h2 Y. A0 Z& ]& X" l! N  }, R
  [) n. q( {5 N, i  z3 l
    user-message (word "There are too many cars for the amount of "
0 s1 }! G! K) L. A/ F  b* v                       "road.  Either increase the amount of roads "
' t4 t4 Z/ O, C" R" v. T2 D& t/ W- O                       "by increasing the GRID-SIZE-X or "
, {+ S# y! n0 p/ A3 P                       "GRID-SIZE-Y sliders, or decrease the "
$ |" H4 d6 z$ a0 }( i$ a" P                       "number of cars by lowering the NUMBER slider.\n"6 h7 B) h- x' ~& ]" z  O1 b$ }' W6 U! q
                       "The setup has stopped.")
+ f, `: U" j9 m) B6 N    stop
! v% b! @% S/ T$ e: `  ]
. ?; V# z& D9 @8 K; n6 e) W! o
6 W6 \# `. I$ t$ S" ~: W+ ]  ;; Now create the turtles and have each created turtle call the functions setup-cars and set-car-color
% f: ~& I' L; R9 ^2 m/ K  crt num-cars
- Y" j3 t4 \3 C3 Y6 V0 D0 Q1 b  [
+ N% y* c# O3 m, {, P9 \    setup-cars
/ I9 _: a: k, N  i; T    set-car-color
( D9 [' p' Z  V7 c% W) t, l    record-data
: h- ?( d' M) H3 n7 d3 l& k  ]1 A' g- K" Z8 q/ u/ Z$ g% `' z

7 X6 D0 n7 N9 |# t2 I0 e  ;; give the turtles an initial speed: L7 x1 a4 n8 c$ ^$ k
  ask turtles [ set-car-speed ]* M- ^9 d% f7 S; i. R" l

( v* o+ j) h& o, [  reset-ticks* e5 |( e% i# c) u; |
end
: P$ H& C7 {4 l7 ]$ q3 |& }1 Z% j+ b5 w) j
;; Initialize the global variables to appropriate values
+ c9 T8 Y( ~; D8 y# c4 Qto setup-globals
* ?) A  i( s2 G+ N; f  set current-light nobody ;; just for now, since there are no lights yet/ `2 t8 K8 V: b
  set phase 0
, V& m! s$ d: N+ L* l  set num-cars-stopped 01 Z+ S8 i2 q/ G/ h
  set grid-x-inc world-width / grid-size-x
+ Y6 e- z, ~; f6 t3 m  set grid-y-inc world-height / grid-size-y
3 o7 [2 T7 [) v/ u8 B3 N! f, D$ d' ~
; I. J: e; o4 P1 s5 ?  H  ;; don't make acceleration 0.1 since we could get a rounding error and end up on a patch boundary" o5 ?* V* s( O* N
  set acceleration 0.099
, C0 T  \4 R' _: G% n  \% T& @$ nend; L0 i% i& I) }" K% L0 K% d
  ]! v6 Q6 Q/ [8 f' Z
;; Make the patches have appropriate colors, set up the roads and intersections agentsets,* ~9 B/ P) U3 L3 Q: ]' v
;; and initialize the traffic lights to one setting/ c" x; R# g6 ~) y6 U* x' r
to setup-patches
$ S& e9 E4 q% F2 m  ;; initialize the patch-owned variables and color the patches to a base-color
( X) K: B) C/ F/ N  K5 @3 x4 l. x# ]- s  ask patches7 q  ]: [- s2 C3 H0 d
  [
3 S+ |8 v. c1 ~4 d' g- W    set intersection? false
% j; {, `# E4 N7 W* q9 Y! j8 O2 L    set auto? false
3 i7 t( k1 b% c+ G* e  p# x    set green-light-up? true5 c; Y8 I9 ]4 e7 j4 t% t
    set my-row -1* u9 X" H" \+ c; [% [' [9 ~
    set my-column -1
4 h+ N" |: M  c5 v    set my-phase -1
; c" M( s3 i" j    set pcolor brown + 3
* v+ R6 _( Q, i6 _5 a2 r  ]2 u# W3 ]' c- C) v, C

# x5 r. H, B- ~" f. L% k8 h$ I  ;; initialize the global variables that hold patch agentsets
& E/ R( [* N/ k  set roads patches with/ m( G4 x- e4 x
    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) or
7 t! ~. \- N* F) m    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]
$ G7 w3 D0 W' ~/ D, G5 S/ Y$ w* f  set intersections roads with8 [9 E- n+ v: M0 \! z, F+ ?! Z
    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) and" w+ B/ v1 n( a' y' t; @& r1 R) F- q
    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]
+ O( X6 l$ ?! J( R& M9 ^( J; q" M* F5 x
  ask roads [ set pcolor white ]  Q. D9 t% b! U! R) A
    setup-intersections
3 E, |7 ?% U$ Bend
) F1 v  Z: }8 G# T  k- L+ W& O其中定义道路的句子,如下所示,是什么意思啊?2 j% u% M# d# @
set roads patches with# [) ~7 C( z2 E) [. f) N; b$ R  J& p4 C
    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) or, O, E4 @0 J7 _/ m
    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]- n/ r. `4 x4 ~3 Z
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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