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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。
  a6 }3 P. Y) h. c1 o3 Qnetlogo自带的social science--traffic grid这一例子当中,
7 }1 m- x7 e- V% \+ c2 q7 ^globals
- J" k7 {4 q) u+ Y. r6 {6 r[
% E. v* @8 d$ s1 A8 m9 o  grid-x-inc               ;; the amount of patches in between two roads in the x direction6 |+ z8 p4 s& |5 v! V% S; V$ ~' L
  grid-y-inc               ;; the amount of patches in between two roads in the y direction3 v. A/ i5 x+ c' K
  acceleration             ;; the constant that controls how much a car speeds up or slows down by if
- r* p* Y( p% l5 |: y. G                           ;; it is to accelerate or decelerate
0 u0 Q+ W8 l9 p2 u  phase                    ;; keeps track of the phase
* c- N- ^7 O' K5 J( o) N) j( k  num-cars-stopped         ;; the number of cars that are stopped during a single pass thru the go procedure
4 Y& k; V% s" m; \- W0 N  current-light            ;; the currently selected light. V$ c& e- h: K3 ^8 X
, _- D/ T" L( _" e0 f
  ;; patch agentsets3 U4 I! N$ r) q2 a. D: l' v# Q
  intersections ;; agentset containing the patches that are intersections
1 v$ e) o% z2 k( v$ W4 x  C0 X  roads         ;; agentset containing the patches that are roads* Z& u$ q: U& b/ L! f/ |
]7 ]+ x% k4 V/ G. ?5 _
( R! J, q6 X7 T& b7 s" R
turtles-own" m4 r! U& {) t' c/ Q% b
[
( ^* [* I; `) P, q7 v, N  speed     ;; the speed of the turtle
7 H  p/ w- ?5 Y" R  @& x$ |  up-car?   ;; true if the turtle moves downwards and false if it moves to the right
3 R) u' E) K. r4 q* x  wait-time ;; the amount of time since the last time a turtle has moved
" e# a- @) P- H! j0 Z# K. k]$ _) z' c, c4 B% Y# d5 D
, I3 V0 ^6 g5 w3 p$ y9 X
patches-own
; R7 n5 U, @  f& R: F[2 M" b# v9 y  D/ a8 Y& \
  intersection?   ;; true if the patch is at the intersection of two roads% T) G- H9 r! ^! ?; p( P1 `
  green-light-up? ;; true if the green light is above the intersection.  otherwise, false.
' B% a0 {+ w! u7 T                  ;; false for a non-intersection patches., N7 ~  J" Q: E( l% t# p/ m. z
  my-row          ;; the row of the intersection counting from the upper left corner of the
7 `& N  b' G% d( q# L( o                  ;; world.  -1 for non-intersection patches.# Q" |) `0 r2 \; b# a' Z8 o
  my-column       ;; the column of the intersection counting from the upper left corner of the
) H- {' E# h5 C: N) q/ S+ n$ j                  ;; world.  -1 for non-intersection patches.( `+ B4 @. h- E4 |% l
  my-phase        ;; the phase for the intersection.  -1 for non-intersection patches.
4 P+ o2 b1 d: k0 w9 O3 y  auto?           ;; whether or not this intersection will switch automatically.- w, l5 L  C  p: O9 e: p
                  ;; false for non-intersection patches.
4 Z0 g2 w) M4 `( w3 X]
1 d- ]: f! e, H- S0 m) R  w: Q
8 A7 S9 @6 E  s8 g4 L5 P
4 d8 o' m' ~; M  @8 X7 m;;;;;;;;;;;;;;;;;;;;;;* p9 S# H  O" p# J7 [- F2 T
;; Setup Procedures ;;$ Y8 A$ X2 D+ X( r1 d: U9 g
;;;;;;;;;;;;;;;;;;;;;;0 r3 R  ]6 K) \: H$ O
# E2 |( G# v; n
;; Initialize the display by giving the global and patch variables initial values., U& K/ M  P  l( v0 l) G2 ]7 u
;; Create num-cars of turtles if there are enough road patches for one turtle to, u  `9 e  {3 t$ c
;; be created per road patch. Set up the plots.
6 ~9 }6 I6 A  s" k- c) a' X# zto setup
  i- E6 Z4 C, B# o  L: O7 F  ca+ h* K* \& u, r, Q' h
  setup-globals$ d: }. @6 ?& `' U

9 N" _" e% \) `0 l5 f7 ^0 A  ;; First we ask the patches to draw themselves and set up a few variables5 m  P( m5 l6 u7 @; ^0 H
  setup-patches+ H' ~) p0 k! h/ \$ U7 l$ n
  make-current one-of intersections2 H* a7 O* y0 s+ L. m' Y( i
  label-current
8 R; l7 ?% a! q) V
1 k4 T: K6 f& Y' }& ~; c8 R  set-default-shape turtles "car"
& \# P0 x$ ^# e" Z1 {# a) f% K# n" c: f
  if (num-cars > count roads)
, l5 a  F! a" o; k) g  [
3 Z' a! K! }% G$ x- }. X" S    user-message (word "There are too many cars for the amount of "  U! p- G$ P4 P
                       "road.  Either increase the amount of roads "
' O5 [7 t6 Q& Y1 ?# @                       "by increasing the GRID-SIZE-X or "$ F5 W$ Q% v# }
                       "GRID-SIZE-Y sliders, or decrease the "% b* l* j. }2 S( p7 a& S0 x
                       "number of cars by lowering the NUMBER slider.\n"  H/ ^  l9 H' W
                       "The setup has stopped.")
* N6 N3 K3 |8 u4 L$ C0 N    stop
- o  i3 h# _4 i8 E  ]  e" z' U. I- r0 a" X5 t$ l
' l4 X. y, i% K+ V2 v
  ;; Now create the turtles and have each created turtle call the functions setup-cars and set-car-color9 a+ n; ]7 p+ q, p7 n5 U, y5 e
  crt num-cars
0 z" s+ n+ g) F: k' f  [
$ I- X# q1 b; j    setup-cars9 _0 e# F' B; Q, L/ D! I* C7 m
    set-car-color0 b, C8 Q/ b9 ~- Q2 ]* p1 o
    record-data
7 Q+ R! _5 \" t4 _) Z5 T  ]; w4 M5 l' B3 T; [, }8 a- V9 s; a
8 R9 r+ c8 c6 ]( A1 ^
  ;; give the turtles an initial speed
% s- f7 y% N3 k4 C7 f8 Q  ask turtles [ set-car-speed ]
  g3 I: t5 q; o( ]7 Z4 N  T
4 {* ^( j! A( G" h" w4 m6 g/ F  reset-ticks7 \0 S$ d4 O. N: y7 A" k5 @
end
3 R! ]4 N* P7 A; f
+ J3 B: _1 d. O4 y;; Initialize the global variables to appropriate values4 c* x& |1 |% J5 d- m
to setup-globals
; v3 {7 g5 P" N  n4 }5 ^  set current-light nobody ;; just for now, since there are no lights yet2 g* w) k8 ?& t& a
  set phase 0  _! k9 @4 K3 x  Y& J% t$ |
  set num-cars-stopped 0; A, R2 {" R/ {/ n  u5 ]1 C6 o
  set grid-x-inc world-width / grid-size-x9 f- C* `7 {4 v3 G
  set grid-y-inc world-height / grid-size-y/ O! c+ R# a; T; u2 M/ O5 @! K
) |+ w' i; g; S- ?  X: d2 \
  ;; don't make acceleration 0.1 since we could get a rounding error and end up on a patch boundary
" E" a9 S* s2 A" A% e  set acceleration 0.099' E! S- |& H: ^( \5 C) z5 ~3 A
end/ a+ }* G8 ?. F4 @$ F

7 e+ G3 K( a* f2 C;; Make the patches have appropriate colors, set up the roads and intersections agentsets,
  S& @0 T8 U" ]3 H. B;; and initialize the traffic lights to one setting/ T/ F1 o: X( `" T3 f( M9 O4 y
to setup-patches
# j8 Y, T0 k3 i7 Z8 h) X3 v  ;; initialize the patch-owned variables and color the patches to a base-color
0 F3 P+ c" h0 D" Z! A) M  ask patches
2 \+ m) L' z: s9 z  [; B; l& w0 m, H3 G8 m2 H0 ~4 t
    set intersection? false
: a1 w0 }$ n0 I8 Z( o: r$ t    set auto? false
0 r% Q! j' j/ s) P4 V3 i8 j    set green-light-up? true
+ ~( z9 R4 j/ t7 a; z* t    set my-row -1
# H" C" q: ^* \    set my-column -1/ {4 D* l" O) }% g$ T6 n5 T
    set my-phase -1/ i8 ~. a: O5 L
    set pcolor brown + 3
+ }0 R- o7 t: ?/ P% {% C3 {% {: S  ]2 E6 E' a4 u' Q

* `- U/ g- y7 S+ ?4 J  ;; initialize the global variables that hold patch agentsets
% O  Y( \: j5 V( V. Y3 j; E  set roads patches with6 h* d( \/ N5 _* U% f# l
    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) or
+ d1 Z1 @1 }  w$ y4 D% Y/ ~    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]
* @2 B* V  d8 ]) T( b) P  set intersections roads with
; B2 `# Z/ \9 q! O" H    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) and  i# P( n$ U. I. S& k- O
    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]! w  Z) f! k5 P

5 e$ V3 v. D& l) y) d7 t7 i+ n! i1 D  ask roads [ set pcolor white ]( h& V1 t* Q! P0 G6 e$ \% |+ g$ E3 l* I
    setup-intersections/ g; K3 U; V5 ]) B! T
end
6 @8 q8 v& [- @5 |' e其中定义道路的句子,如下所示,是什么意思啊?
$ S& m4 T: a- e4 { set roads patches with
" T% u8 x6 }( H: _: E0 o    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) or( h! C6 v* \8 O7 U
    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]5 m. {+ D* B% @  x; s) g2 I
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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