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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。
$ p1 h6 \. o, f  V5 jnetlogo自带的social science--traffic grid这一例子当中,$ c* C$ `. m5 @4 `3 `6 `. ]
globals
) Z2 x0 j% A) F8 J# |+ M[( T$ g- ]* T' r
  grid-x-inc               ;; the amount of patches in between two roads in the x direction
. ], g" a/ I7 ^5 b; U& J  grid-y-inc               ;; the amount of patches in between two roads in the y direction7 ]4 l0 W: l/ i8 [  w! `3 |
  acceleration             ;; the constant that controls how much a car speeds up or slows down by if
/ D+ ^( [6 m: L1 U                           ;; it is to accelerate or decelerate" O; A2 y6 {9 G7 b4 n  I
  phase                    ;; keeps track of the phase
8 X5 f6 }7 \3 C" _8 X& _! J+ c  num-cars-stopped         ;; the number of cars that are stopped during a single pass thru the go procedure, g9 X! g; d: G! C) O
  current-light            ;; the currently selected light
2 L* ]" O7 D5 f, p, _+ m% ?' |9 w( [; {6 [0 M2 r3 H5 D, m9 p
  ;; patch agentsets4 {9 v0 [4 i* o$ R/ ?1 P4 z* x2 h
  intersections ;; agentset containing the patches that are intersections
2 n" m- c2 j- O3 c  roads         ;; agentset containing the patches that are roads
( v7 [! P1 d2 Z+ D]
* O0 v0 `, S* P2 E$ ^# T, m; A$ m+ K! s. w4 ?
turtles-own
1 @8 M: q: W7 d: G[
' z+ B1 ?4 e. Y* `3 ]9 i, ?  speed     ;; the speed of the turtle
/ u% H+ A- y7 q- \6 l) |: r. x  up-car?   ;; true if the turtle moves downwards and false if it moves to the right: E1 N0 M5 ~* L' [6 P" R8 @
  wait-time ;; the amount of time since the last time a turtle has moved; o- A* ?6 C6 E) b
]$ p7 O- j+ _* a* L! i
- S+ H$ ~7 A& `6 M8 W; S, L& l
patches-own
* f% M0 w# L. n[
4 b7 `' q. x- G* u" h3 Z& _5 n# P) T  intersection?   ;; true if the patch is at the intersection of two roads, D3 t/ n5 A5 e4 L" p$ z
  green-light-up? ;; true if the green light is above the intersection.  otherwise, false.* W7 }! j( W( a' Y. k* ^
                  ;; false for a non-intersection patches.
+ C* D, |, E9 O" ~2 U, _  my-row          ;; the row of the intersection counting from the upper left corner of the
, i7 r* B9 }( D: L! n6 U                  ;; world.  -1 for non-intersection patches.
. A( G5 \  h2 Q  Q1 [$ I8 L  my-column       ;; the column of the intersection counting from the upper left corner of the% i# t/ }4 G1 Z. Z3 v0 ?: f
                  ;; world.  -1 for non-intersection patches.
  m1 N* h2 {) g  my-phase        ;; the phase for the intersection.  -1 for non-intersection patches.
* `. z1 A1 u' B# w# d  auto?           ;; whether or not this intersection will switch automatically.* n* O* s9 }' r/ N6 y) v
                  ;; false for non-intersection patches.- P9 I4 a' F+ H: H( T
]
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' J  j. G  M7 w* e9 c- O;;;;;;;;;;;;;;;;;;;;;;* j/ [! H  _- R; ?) t
;; Setup Procedures ;;3 I) n% ^4 s: \* \% Q
;;;;;;;;;;;;;;;;;;;;;;
( ]% n; Z: l( G/ a7 w7 Y6 ?5 F! f5 ~. Z6 Q5 ~& `. i# P1 g
;; Initialize the display by giving the global and patch variables initial values.
  Y% P1 E& S& x. a+ ]8 c, e' X* ?3 S;; Create num-cars of turtles if there are enough road patches for one turtle to, l: I$ `$ H" w( @4 ]$ P: q& v; `
;; be created per road patch. Set up the plots.
# L3 f: Q5 v; e+ M  m& D- Uto setup
7 b1 M) y8 q) q+ s& _% u  ca
* O. w8 e- z. S2 ^2 x  setup-globals& l4 i$ {% f0 S* z! o& k, Z. h8 s
4 h7 _5 W7 H2 [( W
  ;; First we ask the patches to draw themselves and set up a few variables
) I9 N9 x3 C& U; u  setup-patches
1 d) U) Q, ]5 c  make-current one-of intersections
7 Y! y  m7 g  Z% z4 f  g  label-current
: g& k' i$ W3 M* `# r! }( b; `4 W) P( I
  set-default-shape turtles "car"5 Q) a' |9 R$ T# C- y

1 b! H& ~( [+ C4 r1 O* [  if (num-cars > count roads)
( v% {: K5 q4 X) @8 B8 y- F4 p  [
6 {' _+ a- N. a# [, O: p7 }7 m9 `2 H    user-message (word "There are too many cars for the amount of "" p% i" R1 ~  k" U& s; S* g: M' U
                       "road.  Either increase the amount of roads "
* D9 R$ M8 a3 h8 g6 u. s7 y7 d                       "by increasing the GRID-SIZE-X or "
; w* J: ]4 R/ b) q  O& V                       "GRID-SIZE-Y sliders, or decrease the "
, X2 T# F; ^% t/ D                       "number of cars by lowering the NUMBER slider.\n"1 _0 X* e+ ]+ B, M
                       "The setup has stopped.")
0 a) r2 `/ ~# ]. |/ _8 l    stop
! J7 ?% v+ x. `6 j7 ]5 N) i  ]
4 O* O& Y) @8 D6 R% O- O" s: z: Z# I4 Q- `3 R% m- b
  ;; Now create the turtles and have each created turtle call the functions setup-cars and set-car-color
/ l  Q/ N) J1 e5 F7 p  crt num-cars
2 X  I' ^% t+ V# ^5 c+ B  [* l3 [5 {; k2 D( E7 V% t
    setup-cars
( K+ i6 E' t* O8 |0 a7 [    set-car-color
5 U/ S8 M. D4 h1 ~5 Z    record-data5 G3 s5 F) Q* i' u0 U( E' ^+ z! Q
  ]3 v& r+ I- y1 X- p: k: f! U, u

+ T3 b9 {* @! a4 L; Z. B1 q  ;; give the turtles an initial speed& W. h7 d# `& U0 [) r
  ask turtles [ set-car-speed ]
* U. R. \* V7 j( i# u9 H; R* Z4 e2 q' B! X" c! F
  reset-ticks* s) g- _# |" b6 ]( _
end' q7 C  q7 X& O. \5 M

6 B; I: I) z, Q2 J;; Initialize the global variables to appropriate values( @% `% g2 L7 v
to setup-globals
6 y2 _5 h; m3 u  set current-light nobody ;; just for now, since there are no lights yet5 R  w. C! \2 g3 j; c
  set phase 0
( T# @- u# \8 D: p" u* R! ]: v  set num-cars-stopped 0
! u8 c4 r1 c0 u4 w# R( ?  set grid-x-inc world-width / grid-size-x* o7 f5 T3 D  e  m" |
  set grid-y-inc world-height / grid-size-y5 H' I/ M0 I4 X  B$ c; E" q

' Q3 i, w  {4 p; {( \4 P+ C  ;; don't make acceleration 0.1 since we could get a rounding error and end up on a patch boundary, t$ b& _0 W. K4 B
  set acceleration 0.099
  j; a# s  c* i8 u9 send9 b! q% D% q+ h

  O0 Z. l$ W6 c# A' f& K6 B7 C;; Make the patches have appropriate colors, set up the roads and intersections agentsets,
5 A# d* k4 ]# c/ I;; and initialize the traffic lights to one setting
; U8 c% Z. n& [3 k; X' m" Ito setup-patches% i1 Z' ~; @: ?
  ;; initialize the patch-owned variables and color the patches to a base-color: b7 w9 E: ]. Y
  ask patches! [) @# u. C3 _/ I2 Y7 g' ^
  [
4 R% `/ V# A% U1 {7 k, ~( b5 v    set intersection? false
  f* B2 S) m# f, x9 p    set auto? false
2 ]: {: u; x+ q    set green-light-up? true1 p# A$ S6 x- F2 i9 ^) G
    set my-row -1
* m& E5 z: X* K( t8 M' y3 Q7 Y9 [/ ^+ D    set my-column -10 O! y# M4 O6 \4 P* ?5 D7 _
    set my-phase -1
3 j; o7 b5 `2 K$ e    set pcolor brown + 3' s, P- h+ f  \$ w# L% f
  ]* W4 T5 G$ q/ q1 @/ x4 k( c

4 R" D$ j6 N9 H7 l  ;; initialize the global variables that hold patch agentsets! f8 P; f4 {# K2 a. K6 B) T
  set roads patches with
1 a" P( G1 B$ F6 m9 i    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) or& @6 X* C4 O' [5 k  @: }
    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]  c8 b' l7 z' i( w( n. q. [6 e
  set intersections roads with7 d% j6 V( |3 t: |& T' f
    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) and( s8 d4 @5 {% M( P4 F0 ~* j
    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]( F1 s. u2 P! t- m9 i  U1 Y
5 ^! f6 l+ ~% {0 j* F5 g. W
  ask roads [ set pcolor white ]6 C3 |2 T( Q5 M! [$ r6 M4 L7 M
    setup-intersections
4 g5 g. t: p, w2 Send5 I  n4 S. ^9 l2 }7 J$ [* y
其中定义道路的句子,如下所示,是什么意思啊?3 R3 I  p0 W9 R* [2 a, @
set roads patches with
7 e+ s. _  Q0 {3 V    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) or
$ s+ Q8 E- V1 |2 S$ W( v3 F/ ^    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]8 v) j) R0 F6 s: f% q- h% G" Y, G' O
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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