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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。$ @. r# n: Q! j/ p; o/ [: F* Y% K$ t, J
netlogo自带的social science--traffic grid这一例子当中,+ B7 j6 R$ t9 Y$ }. \
globals7 o* B, `- W! n% m3 C9 }# ?/ Q
[9 Y; E5 I9 |* q, O9 n7 c
  grid-x-inc               ;; the amount of patches in between two roads in the x direction$ E" W8 Z  ~. s8 b  c& p
  grid-y-inc               ;; the amount of patches in between two roads in the y direction
: t& }3 S' ^. R5 i2 @% r  acceleration             ;; the constant that controls how much a car speeds up or slows down by if
, ]" V4 Q$ L" Z9 R( Z1 U, R# p                           ;; it is to accelerate or decelerate' @# g- _+ q# q" N
  phase                    ;; keeps track of the phase
; f" f( P' f) s2 j  f& [  num-cars-stopped         ;; the number of cars that are stopped during a single pass thru the go procedure5 L5 i  h/ t4 m, E% H' \
  current-light            ;; the currently selected light" q1 z5 X- _; e# R9 P: u) I8 k, l
& Q5 T' @% s6 ]8 D: ^9 Z
  ;; patch agentsets
2 |7 e  b$ F8 x  V) P8 ~  intersections ;; agentset containing the patches that are intersections2 P: @1 Y5 L& R( |
  roads         ;; agentset containing the patches that are roads
- J- }& x7 S& i( _) y& r: m]
3 h* R5 |% j1 @, B& M, @
4 f3 |# q4 g' W, m1 d8 v. Qturtles-own
" n# d. d; z( b[1 |& m& m+ Q- K0 M
  speed     ;; the speed of the turtle) N- j( ^$ @5 z9 e/ t- I
  up-car?   ;; true if the turtle moves downwards and false if it moves to the right
) }3 s2 D# `% M7 M* w. ]$ L  wait-time ;; the amount of time since the last time a turtle has moved) s* Y% t; K, _: I
]
+ o! m2 B0 i5 ?% O
' U: ]* |% I  H% }patches-own
7 e- G: M) g6 {  e2 p. p# X" b[8 ]. g* `5 Q% P* z) Z
  intersection?   ;; true if the patch is at the intersection of two roads
! z2 q1 C. w) O0 {* e  green-light-up? ;; true if the green light is above the intersection.  otherwise, false.
+ q2 |8 Z! r' r3 j3 c0 f$ c# E                  ;; false for a non-intersection patches.
" Y( M" e5 C+ A0 V+ a) N  my-row          ;; the row of the intersection counting from the upper left corner of the
6 L6 ]/ j0 O5 W& D                  ;; world.  -1 for non-intersection patches.4 U; v5 r6 U, [5 x* v% ~
  my-column       ;; the column of the intersection counting from the upper left corner of the2 ~4 a8 W% Q. ?; c6 {" K! k" W
                  ;; world.  -1 for non-intersection patches.
9 r2 c4 `/ W0 N# j% q6 z7 O% P  my-phase        ;; the phase for the intersection.  -1 for non-intersection patches.
6 ^6 o* X* k2 U, o  auto?           ;; whether or not this intersection will switch automatically.
) F$ a( }1 b4 L' ]& b% [                  ;; false for non-intersection patches.
2 a5 ~; e6 T+ j; _: }+ Z]+ [. m+ k) U: `1 _  k" @

0 Y4 z$ O3 y" S$ X- x. R; o. q: o: R' U# x
;;;;;;;;;;;;;;;;;;;;;;
6 i- T+ z7 ]* G4 l; E;; Setup Procedures ;;+ U2 U7 a' Z# y7 \
;;;;;;;;;;;;;;;;;;;;;;
+ H7 B% `2 j! _* L$ u
, ~& c9 t- }9 \* T6 h;; Initialize the display by giving the global and patch variables initial values.
5 c8 y8 d& w0 D6 U; _# t# Y;; Create num-cars of turtles if there are enough road patches for one turtle to
3 E! h, Q; g! `;; be created per road patch. Set up the plots./ }4 z+ ~& ], z6 L) q7 b/ l
to setup
9 E7 o5 Y& S  E0 T3 A( @  ca
' B. X- D9 Y8 |% \" s. o  setup-globals
+ L: h- o( V- ?2 \; ^( W5 q
8 g- ~( K- h) t+ _) t3 D0 _' @8 z  ;; First we ask the patches to draw themselves and set up a few variables
2 D2 M# S  ]$ b0 Z  setup-patches! Y. {; r$ Z# V* J/ I: @
  make-current one-of intersections8 R6 ?5 r0 T% D
  label-current
( V4 r; v0 X- b8 ]! B! V" W  s0 D6 A+ ]
  set-default-shape turtles "car"# T& M9 t" g( N) w
" K* L+ O2 p2 U8 s1 V- D5 b
  if (num-cars > count roads)+ R3 r* w( A5 f; K% Q/ i
  [! @' k! o/ l1 e
    user-message (word "There are too many cars for the amount of "$ w+ t4 \+ i% a1 m) {: I
                       "road.  Either increase the amount of roads "( I( }6 m) m9 d% M8 b
                       "by increasing the GRID-SIZE-X or "9 d5 q, t' {9 q6 U. _
                       "GRID-SIZE-Y sliders, or decrease the "* N. j; |/ l  \# G! n$ \  r
                       "number of cars by lowering the NUMBER slider.\n"" R4 s& t& ]$ r; j% L
                       "The setup has stopped.")
( Z- R; n6 i) a3 T% z    stop+ c. D" F& f- B
  ]2 P' w# Q: Z# C3 C; b) b

' O3 i) n) A' P/ B# q3 i  ;; Now create the turtles and have each created turtle call the functions setup-cars and set-car-color
, R- c# X5 n4 Y5 l9 J9 G7 ]  crt num-cars
0 x' D* Q. ~5 Z8 x  [. l1 J/ d5 U9 w3 [9 j& v7 N
    setup-cars
( u( T1 Q! _* K* T8 k5 C    set-car-color
- c  Q! y3 `- k    record-data
9 Q! V. x) e: L3 |* o! g  ]
* }6 V* m' V5 s7 e) T7 I( K: t1 A+ a- c. r8 i
  ;; give the turtles an initial speed' @/ f/ x. ?- i/ L  K# f+ s
  ask turtles [ set-car-speed ]
# s7 s, T% Z  o; Z4 i7 X
4 O' S! F1 f$ v  reset-ticks
/ Q* P4 _' `# {end7 b% f* ?7 j# k2 A( h* ^6 N

: Y0 H; z# l7 \- d;; Initialize the global variables to appropriate values: w; c. ^( g8 Z" ~
to setup-globals
% q. g+ S' B: C9 P. y( l  set current-light nobody ;; just for now, since there are no lights yet' G; L$ T" v. I, G
  set phase 0
& s  R+ p/ ^: _4 P- k  set num-cars-stopped 0+ {4 n( w+ [; V/ \  l
  set grid-x-inc world-width / grid-size-x, g$ I# |2 B3 D1 g
  set grid-y-inc world-height / grid-size-y
" n8 }% M6 @% J( q7 @+ g/ {' x9 N+ y+ R+ s2 i  K; x
  ;; don't make acceleration 0.1 since we could get a rounding error and end up on a patch boundary
, Y/ v: I8 S/ c/ @% E  set acceleration 0.099
5 S4 g/ D& d* Yend
$ U8 Q  P8 p3 ^8 x8 K2 G* U. }* G+ y' ^' }( B
;; Make the patches have appropriate colors, set up the roads and intersections agentsets,4 W( Y3 T* q$ l
;; and initialize the traffic lights to one setting
0 Y: E. @3 z3 x8 A0 X, T3 kto setup-patches
5 Z; e- c; ~" e% d7 K. C# S$ _1 _! C  ;; initialize the patch-owned variables and color the patches to a base-color
& S+ r2 s, w' h, H6 @  ask patches
: T2 B8 h  j+ U: _/ M2 F+ D  [
/ Z, t% [/ Q4 k% H2 p) E- W, f    set intersection? false$ @9 v9 ]3 ^0 O0 s7 l! d3 m
    set auto? false5 k1 ~  L8 w9 x% P4 _, X
    set green-light-up? true" n5 n9 |. |+ C
    set my-row -1
+ M. I7 ^. T. k4 a4 o, n    set my-column -1
2 o# ^" G" ?, t, }; n2 v0 W. p    set my-phase -1
# q& F; L, j: c3 Z    set pcolor brown + 3' \+ A4 D. Q& u, ^& K" Q
  ]
7 \. d$ l( z' U" D0 b/ ]7 D  \* a" X" t: j) E9 l4 U
  ;; initialize the global variables that hold patch agentsets" {: p2 E. n; a) R! q& q  W
  set roads patches with; M) A' J; S; f& L2 t
    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) or* k; p% \6 U5 z, V  v; A
    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]- E2 w1 Q# }+ T& W
  set intersections roads with! I6 }" K- e& z' O4 d; L
    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) and
' d0 ?" Y2 S& {    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]; U0 V4 o' ]- C8 X& e
( Y7 E; y* ?# |! ^3 V( b, _
  ask roads [ set pcolor white ]- k  Z* ~$ o- n9 }! @: T8 B& P2 x
    setup-intersections
, D9 H3 e6 g" W/ uend7 ?4 |7 {9 ]0 S4 A% ~; ^9 q* X0 J" ?
其中定义道路的句子,如下所示,是什么意思啊?
: F/ ^' N6 M8 c' N' |7 h" [1 ^) @/ O set roads patches with: Q! M  t/ d  x/ }% l9 Q
    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) or. n6 f! u& y& K, O& I3 w" K% I
    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]' h* a+ G+ Y  S# E0 Q. @
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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