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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。
( p8 K4 f; [% y* Z  N6 Snetlogo自带的social science--traffic grid这一例子当中,* z3 ?0 J5 }" D1 s7 }, q2 l
globals; A; i: a7 M8 P
[& o+ V7 ~- w$ U
  grid-x-inc               ;; the amount of patches in between two roads in the x direction
5 Q+ H) U) J5 N) ^# H. q  grid-y-inc               ;; the amount of patches in between two roads in the y direction
2 ?; K7 D/ B# T5 Q  acceleration             ;; the constant that controls how much a car speeds up or slows down by if
+ G( y) F$ U3 V# E! P                           ;; it is to accelerate or decelerate
- C3 V  w, L& g/ T1 @  phase                    ;; keeps track of the phase9 i. |, x- `: P1 G( L& G, m
  num-cars-stopped         ;; the number of cars that are stopped during a single pass thru the go procedure' d3 D4 A5 G# R" t7 [+ G' X
  current-light            ;; the currently selected light
! L) l  I! U7 |* M
5 }5 h8 Z8 X0 n/ h! R. G  ;; patch agentsets0 l" ?1 x8 c  G/ G
  intersections ;; agentset containing the patches that are intersections5 D2 ^/ ?+ I" k
  roads         ;; agentset containing the patches that are roads0 P; a6 e& W4 D2 `# b: B: K- s
]
# a: A+ v* U: Q# B
5 |9 ?# a, W5 }2 j/ x, C1 a  ^turtles-own* H5 a9 B; i2 C, m) w
[4 w+ M% g! s8 C3 ^
  speed     ;; the speed of the turtle, n# `% l2 ]6 A  _! s$ z% j6 f8 C& b
  up-car?   ;; true if the turtle moves downwards and false if it moves to the right
. y2 T# \2 `- O1 n2 t& W7 P  wait-time ;; the amount of time since the last time a turtle has moved
% |" V" S! L2 S- d. Z9 l]8 r5 h( I+ v3 o( i

" |& c: B( |0 Y! \/ L' r' Rpatches-own' @' t" \( S& p! m4 A& F* c/ [
[
* n+ c1 I( q- r  intersection?   ;; true if the patch is at the intersection of two roads! `! J1 w! X/ }1 Z6 g' _
  green-light-up? ;; true if the green light is above the intersection.  otherwise, false.5 A, c4 Q* k* l, g1 b9 `, s
                  ;; false for a non-intersection patches.
; F" n  T0 v  v, v- U2 o- b. f" A) U  my-row          ;; the row of the intersection counting from the upper left corner of the
7 x) t. B* ?! Y8 @" y                  ;; world.  -1 for non-intersection patches.7 X1 Q. ^* C8 f9 n( @
  my-column       ;; the column of the intersection counting from the upper left corner of the
  a' g: n0 C6 L* l, }) `                  ;; world.  -1 for non-intersection patches.+ p; R1 e% {# E
  my-phase        ;; the phase for the intersection.  -1 for non-intersection patches.
- }# s  w& A$ a* p" O% |. _1 F, O7 L/ C  auto?           ;; whether or not this intersection will switch automatically.
" X2 L* g& w  n5 ]1 X: N" L                  ;; false for non-intersection patches.
! E( s# T& i9 ~7 S]
* c6 a2 ^: M; O7 H7 A: }6 c
, c/ {; i2 S% J: |9 q, p2 a
: A1 I7 L4 D+ m1 G" }7 t' d1 `;;;;;;;;;;;;;;;;;;;;;;0 R$ p; B4 J, D* L& j% u  S
;; Setup Procedures ;;, c9 Y2 o& K7 j: ~* v; M
;;;;;;;;;;;;;;;;;;;;;;9 i! Q6 e# H8 X0 z) ^

$ p2 e/ g! L$ Z;; Initialize the display by giving the global and patch variables initial values.
1 G7 p; r% z! y1 _- c* z;; Create num-cars of turtles if there are enough road patches for one turtle to" Y' t& e6 y0 e1 v8 N' z( k
;; be created per road patch. Set up the plots.
& v1 j8 j: O" M9 F  O3 l$ t# Vto setup
! q6 B$ i/ N+ M1 w, Q% c  ca' s- P0 C! E+ ?# X( K7 z. R
  setup-globals
$ X  B+ B, Z8 I* Z
! i" J; Q+ Q# ]( [6 ]& E% Z4 F. g  ;; First we ask the patches to draw themselves and set up a few variables5 V- ?/ Q/ A! T3 N& y% v6 j; ^7 R9 w
  setup-patches6 `* I/ j9 I+ k0 _. N9 e$ }8 c+ m8 T' A
  make-current one-of intersections
2 N( A8 H- S. g# _. z  label-current5 l2 A6 H$ X- |( i7 [* o, m

/ h3 I) Z; Q9 o3 C; o/ n5 H+ d  set-default-shape turtles "car"
- y, W- ^7 {4 R# A& z3 c0 ^4 d* _/ O. ~9 Y
  if (num-cars > count roads). F, y' C% R2 z$ t
  [
2 d4 o4 v1 W* v$ t- s" ]    user-message (word "There are too many cars for the amount of "5 h7 H" ^# i+ J
                       "road.  Either increase the amount of roads "
- N# g2 u% ~; |# k) [: u/ m                       "by increasing the GRID-SIZE-X or "2 L* c9 ]: _+ L4 q  l
                       "GRID-SIZE-Y sliders, or decrease the "1 S, \5 ?; @0 i
                       "number of cars by lowering the NUMBER slider.\n"5 u! C7 @; W* L5 U" p
                       "The setup has stopped.")
4 n; \6 e. B: {+ t& \7 o' Q/ \$ m    stop: ?" p* T4 d. K
  ]9 g, y7 M  _6 q5 V8 B3 O, I$ l
( a) T$ q$ J( V2 w- T
  ;; Now create the turtles and have each created turtle call the functions setup-cars and set-car-color
' _9 c" Q4 p: @; O+ ?  crt num-cars; u' s+ m+ x: Q8 b8 z  \
  [
) s# S  |% G( r    setup-cars6 }$ _2 @3 @# X6 |9 f
    set-car-color! t+ s1 m+ Q! x" L1 ^7 u. n- ]
    record-data
; [* t+ Y* ]2 B7 U9 ^  ]
$ I3 V# Y" Z2 B9 [. g- U- _! S0 n& b
  ;; give the turtles an initial speed# M" d7 n( Z* r6 G, C
  ask turtles [ set-car-speed ]" t! ]5 d3 s6 W# o5 U. c
' G6 m4 [. J# o5 Q# e2 {3 ?+ O
  reset-ticks! `7 J" s) l. }! Q8 k1 P8 E
end  }" [  d$ w$ @- e

" k' x1 G6 k- _9 x. Q# H9 P;; Initialize the global variables to appropriate values
" S7 G) H/ W0 tto setup-globals$ _' V. u+ {% K. `$ R  S- b3 G
  set current-light nobody ;; just for now, since there are no lights yet2 y& h. l  e, v4 H
  set phase 0
" Y' _  X& y9 M& Z4 g  set num-cars-stopped 0
' [6 w, c& O! q7 q7 E; k, T8 X# x  set grid-x-inc world-width / grid-size-x0 o4 X* @/ L1 |2 B
  set grid-y-inc world-height / grid-size-y' Z0 l6 _% ~- O1 @1 _

/ u( A" d5 Q! ~: M2 I  ;; don't make acceleration 0.1 since we could get a rounding error and end up on a patch boundary$ \+ d1 U% Y! D% l- g2 x3 Z
  set acceleration 0.099: h# A' N9 B7 H  @4 X
end
( s: ~0 c# H) ^  ]
3 C) {6 u7 b( v/ `- u& C;; Make the patches have appropriate colors, set up the roads and intersections agentsets,
* N. E# u6 x; _% F;; and initialize the traffic lights to one setting9 Q, f9 n4 {8 `1 X" z/ |
to setup-patches
* \$ W/ |$ _9 f/ ~  ;; initialize the patch-owned variables and color the patches to a base-color: G# ^. G4 |7 V
  ask patches
" O( G8 Z7 Y& P' O  [
7 i) C9 B: p) R, X3 f9 }0 s2 O# q; p    set intersection? false% ?! [9 |& m$ ?+ Y4 m" M, [
    set auto? false# f6 h+ |+ M# ~. x- d+ p
    set green-light-up? true$ M/ _0 [8 [) \! M  v4 T( H5 [6 b$ T
    set my-row -1% x8 P* S5 s7 R
    set my-column -1  j) w8 A) g# B9 q
    set my-phase -13 C; _: C4 ]' B" S
    set pcolor brown + 3
7 \0 K* v& Q* H( F& k) X  ]
1 q( \7 M- }/ J! d) E3 L
4 t8 N* u+ u2 g) \3 E  ;; initialize the global variables that hold patch agentsets
* }. J- p2 T$ A  set roads patches with
# U- ]5 N! {2 [- U& v+ P    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) or
* x! o7 Q, C% x: r; H/ q3 z5 |- ]! J    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]
; i; y- ^# ~; R" \" G  set intersections roads with( H# `4 ^( u/ l4 h$ G( w  m6 p
    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) and2 W2 N1 t. r: }: a
    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]1 k# v: R2 T$ A8 @5 K  h

2 H' K  n" c) B! f$ h0 T& U  ask roads [ set pcolor white ]/ z, O; B2 T: X! E
    setup-intersections: s* n. v8 |  n
end
+ Z: ]" w0 H1 v# j" C8 V; g2 Z/ a其中定义道路的句子,如下所示,是什么意思啊?
) g( ~$ p: h( Y0 }5 k6 X set roads patches with
. B; z( {& F$ p: B" z4 j9 M    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) or3 R4 x) E' @4 A/ R& A- j- Q/ l
    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]
4 K+ \- b- y  M; F5 i- 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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