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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  u1 |' y9 M6 V8 F& L: N
netlogo自带的social science--traffic grid这一例子当中,  `7 a9 P* z8 o! y6 K  K
globals# A- e( O% @6 Y% Z: d$ q
[/ w0 c7 n: |+ j& t$ H
  grid-x-inc               ;; the amount of patches in between two roads in the x direction3 }( H& X: q& f4 q  A8 J* P/ i
  grid-y-inc               ;; the amount of patches in between two roads in the y direction
8 f: @; k& J0 x3 s& k9 E7 c  acceleration             ;; the constant that controls how much a car speeds up or slows down by if
" I: d. z+ _* t" r/ P- m                           ;; it is to accelerate or decelerate
; r$ e4 I4 |, I9 M  phase                    ;; keeps track of the phase
+ ?/ e$ \/ z! u2 }) @5 }* l  num-cars-stopped         ;; the number of cars that are stopped during a single pass thru the go procedure
& Y3 S# e, J# E5 B$ H( R  current-light            ;; the currently selected light
- d* w( v! ~& A& p$ F2 @1 O2 l8 Y' @1 I) I0 R
  ;; patch agentsets
" _" u2 L% G& {5 p  y0 u  intersections ;; agentset containing the patches that are intersections6 n1 ~/ B! ]4 ]( H: S' m" Q# D7 Y; e
  roads         ;; agentset containing the patches that are roads# @  b# _0 L3 ~: N' b
]$ E, K2 k( l3 k6 q/ `
+ _6 P8 E! r8 n2 u4 g: M$ ~+ K+ R3 _
turtles-own6 L" K* n7 D: k
[; x( E2 u. R6 O+ O
  speed     ;; the speed of the turtle
* a" o6 A3 z3 \/ U# N% l  up-car?   ;; true if the turtle moves downwards and false if it moves to the right9 R. F" @; H$ t7 c
  wait-time ;; the amount of time since the last time a turtle has moved7 m4 {8 k8 j: w* [2 @
]  g. t6 V' @4 E2 |% N

& m) D6 m( ~) x+ m# f1 Opatches-own
) p% g5 k6 A  Q- S' x& ]8 B[
# J3 S  G6 _. y0 q2 n( X  intersection?   ;; true if the patch is at the intersection of two roads5 r2 d6 t2 a, S8 t9 q' h% e+ N) @
  green-light-up? ;; true if the green light is above the intersection.  otherwise, false.
: L( w: u' j  \) s* e' v                  ;; false for a non-intersection patches.
6 F9 o" L0 J3 u3 g' z  my-row          ;; the row of the intersection counting from the upper left corner of the
* ]8 E/ s, F6 w) o) C" q                  ;; world.  -1 for non-intersection patches.
, S4 x) R/ u6 V. V# ~$ M  my-column       ;; the column of the intersection counting from the upper left corner of the! m$ E" o/ s+ E8 D
                  ;; world.  -1 for non-intersection patches.1 n4 w, q" G# ]
  my-phase        ;; the phase for the intersection.  -1 for non-intersection patches.+ F2 i1 o6 k. g
  auto?           ;; whether or not this intersection will switch automatically.! j! ]1 c" {' \( i1 E1 t- r5 ^
                  ;; false for non-intersection patches.7 x: \) h% ]5 M$ B; c
]
: @- V# r3 L- Y1 t
* O. \2 W9 D$ d( b$ }- b4 O
8 B! c3 l6 {! Q; |5 m: d+ i2 M;;;;;;;;;;;;;;;;;;;;;;9 w  \/ u* F# i  A0 _" O
;; Setup Procedures ;;
0 p' r. S' _1 W7 F) W8 O;;;;;;;;;;;;;;;;;;;;;;9 A1 x. T8 i0 o/ ?; ~) l
' A/ V: T6 c4 q) j5 f% K8 W
;; Initialize the display by giving the global and patch variables initial values.2 M6 m) r3 Z  G+ C
;; Create num-cars of turtles if there are enough road patches for one turtle to+ r( C' t& K' D0 n0 ~
;; be created per road patch. Set up the plots.
9 G) ?5 |& a3 [9 q- [$ [0 Nto setup, Z" h# x& z- ~$ t, Q
  ca4 h( W- Z4 i8 i8 v9 u# g
  setup-globals+ _0 o. t7 F+ R

4 o  _+ {; e* o% w4 e  ;; First we ask the patches to draw themselves and set up a few variables2 }$ l* g, |: L' D4 i3 J8 W" d
  setup-patches" s7 \6 s: {+ Z3 m+ H! ~$ H
  make-current one-of intersections
/ ?# B* i, w5 }  h3 F8 Z" Q- q  label-current$ u+ K+ q0 A3 e8 G8 X6 z* D9 f
9 P. v- v+ n& O5 L1 D9 ~* X9 C5 t
  set-default-shape turtles "car"0 `$ r2 n: h* e6 {

5 V- @6 @4 t4 M/ l. D0 w: J  if (num-cars > count roads)
1 O! t# y, @" B" S  [
, T& T! I6 a4 ~4 X9 n& `    user-message (word "There are too many cars for the amount of "
. q) v! \1 D1 V                       "road.  Either increase the amount of roads "
4 {4 u+ Q) H/ A4 e# P                       "by increasing the GRID-SIZE-X or ", ]; V% y6 L4 ?# l4 T' f
                       "GRID-SIZE-Y sliders, or decrease the "
: I% Y, O6 J) p7 a2 u" s. H                       "number of cars by lowering the NUMBER slider.\n"
9 L$ y& {6 ?+ p7 ?" ~                       "The setup has stopped.")
, S. d5 _( K7 F( ]    stop
" k: e- L( z5 a: _0 t5 z  ]
% O, B. Q3 h* z1 _8 ]) ~& Q0 |( M6 H% t
  ;; Now create the turtles and have each created turtle call the functions setup-cars and set-car-color
6 X6 I% b$ C/ D) o; h  crt num-cars% X8 |& w+ @9 {+ a
  [
  i4 l! |$ C% a$ N1 d    setup-cars
/ Y  A$ L0 H. D! ]7 K    set-car-color1 `" o8 }9 H; ~8 g. [2 a6 \
    record-data
; Q9 y* }* U" ~7 ~* I: }  ]
) |* e. v2 g- {, i4 i, [7 A4 J0 P7 m' u" _6 n0 B
  ;; give the turtles an initial speed( A+ f: U9 S9 q% N& \, A! ]
  ask turtles [ set-car-speed ]4 a0 p4 g$ V; L4 i7 ^8 j# u8 i

. T5 n3 K2 Y7 n* N  reset-ticks
. a+ c! @2 t4 @  {2 g2 X$ C  a  Vend9 e8 t1 _9 |8 x  U; ]
6 Z, I' l/ U+ |% ?
;; Initialize the global variables to appropriate values
  y* A1 S7 f* G4 Z" e% ^( Kto setup-globals
* |8 }' w. o" v# u  set current-light nobody ;; just for now, since there are no lights yet
4 I/ d; l- j. e4 g  set phase 0. h0 c+ E' D9 y
  set num-cars-stopped 0
" x: u7 u8 t8 Q8 p# y) v" w1 j  set grid-x-inc world-width / grid-size-x$ ^0 O" Y& }" I6 D5 }  @/ O
  set grid-y-inc world-height / grid-size-y
! o! M3 A: S+ b) l) S6 _  Z  }9 m) l7 z' l
  ;; don't make acceleration 0.1 since we could get a rounding error and end up on a patch boundary
/ ^/ E) }/ g- ~3 I  set acceleration 0.099* N3 S; |* K) `+ K# Y
end! t' D4 X% F  P2 {2 K0 w

2 t6 i" Y( C/ P, R0 h6 m2 g, C;; Make the patches have appropriate colors, set up the roads and intersections agentsets,: ]& A  S4 O% R6 ~$ x/ i/ L
;; and initialize the traffic lights to one setting4 t* A+ ?$ \4 i; Q* u
to setup-patches2 [, }2 w1 T  y  ]+ }2 A
  ;; initialize the patch-owned variables and color the patches to a base-color
. I" c, R; E% H  ask patches$ ?. `7 O+ O/ H: T# S4 q
  [  j) K) J6 ^% J
    set intersection? false" L8 w" y% D, r2 ?) a! i) F, Q
    set auto? false( @" ~5 |9 G- K, n. W' ]
    set green-light-up? true
$ n6 t9 A. K0 v( {) m. d; {) Y    set my-row -1+ \' @: Q# K* t$ x2 i, T2 o& M& b
    set my-column -1
; s# c8 H0 K+ N9 o    set my-phase -1
4 _' z+ D% `6 t' Q    set pcolor brown + 3
4 h1 f  M8 \6 X/ U6 P4 E/ r; p: b  ]8 o& F: u3 n) X% e; M3 K% H+ f7 M4 P
6 g1 j  _2 V) \
  ;; initialize the global variables that hold patch agentsets
8 r  d4 N5 t" k5 U  set roads patches with+ C6 b- w8 v6 q1 _- S5 i
    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) or/ p4 q: I6 u& G# s) L# x: m
    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]3 K4 t+ o$ ]* q5 ]* Q0 d
  set intersections roads with9 O! m+ V! j+ I) n3 T
    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) and3 v/ s1 M, F/ E7 y( F
    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]& i' j, k( L( c
: ?, n& E! n* ^' @
  ask roads [ set pcolor white ]7 o  \  x) H* `: M3 N5 @& g1 c
    setup-intersections
! `5 c6 b7 t7 yend, ^* R" |7 q! x& t+ M
其中定义道路的句子,如下所示,是什么意思啊?
" |: w$ y6 u* g4 W+ v( H) R1 i+ @# f set roads patches with
$ K3 S( N4 b8 U    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) or3 c' u- b8 y+ i* c# m3 ?
    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]
$ Z. i# D  i, f1 h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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