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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。( W6 H$ A" h5 Z1 A$ o1 i* J
netlogo自带的social science--traffic grid这一例子当中,' h# G7 M% v- f' \% _  Y$ r
globals& L0 N+ p7 \/ {/ t: x! I* r; |
[
: i7 @4 `. ^5 y- a/ l( s8 I  grid-x-inc               ;; the amount of patches in between two roads in the x direction
' c# F! g1 d# r" f  grid-y-inc               ;; the amount of patches in between two roads in the y direction
# f9 _6 E: I5 i# v) v" R  acceleration             ;; the constant that controls how much a car speeds up or slows down by if$ m# X+ K4 O: J7 G1 I9 y
                           ;; it is to accelerate or decelerate, @2 A. U- k) G0 t8 i! k' s& ?
  phase                    ;; keeps track of the phase
/ w# H. T5 x0 h, c3 x  num-cars-stopped         ;; the number of cars that are stopped during a single pass thru the go procedure6 ]' n9 o8 o+ G2 O4 P
  current-light            ;; the currently selected light0 z  a  r, Q8 j% S4 N& Z
5 H; y0 y- l+ h8 L: u) T
  ;; patch agentsets
" B- a/ ~8 F, C" ]. l+ F# f  intersections ;; agentset containing the patches that are intersections
) l5 e- P1 L6 z  roads         ;; agentset containing the patches that are roads5 B8 S. q: G& \+ T3 l( w
]/ n3 h1 d1 p2 L; r

& s* H! p9 X4 j; F2 `& {turtles-own. {# w- U* i3 {" L# v: }& W) V; z
[
$ ^$ j% \$ W) l  speed     ;; the speed of the turtle
9 M% o$ B8 ]9 ~6 M8 X: V: X& N  up-car?   ;; true if the turtle moves downwards and false if it moves to the right
# i, x# A! U% D7 ^; ^! N& P/ P6 q  wait-time ;; the amount of time since the last time a turtle has moved. X" r8 k; R7 B) S: z( r# R1 @0 Z6 z
]
& e( `# q1 Z* b! l. u
+ _3 }1 E: V7 |9 ypatches-own
" h0 c% O( o% f) g; I0 N) o[6 S" R5 ?0 H- b4 T, f4 Y
  intersection?   ;; true if the patch is at the intersection of two roads
5 N/ ~( M% |7 j- n: ^  green-light-up? ;; true if the green light is above the intersection.  otherwise, false.5 \: D4 j# h* B1 V* H- Z* c
                  ;; false for a non-intersection patches.0 m! i. s4 K( J' g2 @
  my-row          ;; the row of the intersection counting from the upper left corner of the
9 X3 K/ E( j/ D: x1 ]                  ;; world.  -1 for non-intersection patches.
0 U7 e9 P/ @. b4 ]2 l2 h# u  my-column       ;; the column of the intersection counting from the upper left corner of the3 b  }) A# ?0 z
                  ;; world.  -1 for non-intersection patches./ i/ H0 o4 t! r/ \3 _& v2 M! a: f$ p
  my-phase        ;; the phase for the intersection.  -1 for non-intersection patches.& J7 J6 q9 ^2 G, g
  auto?           ;; whether or not this intersection will switch automatically.
! s  b5 f) p0 f* V! L5 ?                  ;; false for non-intersection patches.$ o- i  h$ o1 `; T& O# ~
]
3 K1 r% {9 t3 N3 R6 B/ W2 K9 Q" j
/ q9 g3 N# |* g  D  X$ n$ u# I  c2 A0 C
;;;;;;;;;;;;;;;;;;;;;;
& X8 J% i9 y5 }9 y  ]2 I" W;; Setup Procedures ;;
' u. ?0 L* J, s. x;;;;;;;;;;;;;;;;;;;;;;4 x# K6 U; J2 R  b
6 v7 I. C& V6 B# A9 s
;; Initialize the display by giving the global and patch variables initial values.: Y4 k; E7 O5 q6 E. \. s4 ^  N9 E
;; Create num-cars of turtles if there are enough road patches for one turtle to+ [9 B  }8 K+ ~: V; {
;; be created per road patch. Set up the plots.
6 a$ q2 B) b6 L# I6 Tto setup( z8 G. O2 ~# {9 r
  ca
# ?  |$ I: @. G% V6 \  setup-globals
3 W4 y. P1 }' R  d  G3 ?
- _+ u2 b) B3 P( A: _4 d  ;; First we ask the patches to draw themselves and set up a few variables
9 ^# D& x' _- O/ N7 x  setup-patches7 b# e, }2 }% T" c! h( k4 f
  make-current one-of intersections
1 N3 W* Z) J9 U" }  label-current
  P2 C8 w  O. b) B% i" H% i
: U9 r# Q/ W/ k; ]9 K3 A; a$ n  set-default-shape turtles "car"( r# W: X5 U. \# @8 e" Z0 `! E

1 M* g6 U. N( V  i2 L  if (num-cars > count roads)
: N0 j7 w0 E0 }  [! r% {- H2 U* W9 `! j6 J5 u4 b
    user-message (word "There are too many cars for the amount of "# x: P; s- i! {9 p, j: |
                       "road.  Either increase the amount of roads "  P+ H9 E" y) m2 B
                       "by increasing the GRID-SIZE-X or "; q3 F& z( u4 x8 d7 W/ z
                       "GRID-SIZE-Y sliders, or decrease the "2 S; B( L8 [) L: d, O( t
                       "number of cars by lowering the NUMBER slider.\n"
% b# D; U* X9 v4 o: Q                       "The setup has stopped.")
8 l) H8 H. L4 F% ]; K" u    stop2 [% A1 P3 c6 p! x( m
  ]
( _& I4 ?1 p6 L0 q
9 |) h& H  E/ F" n% `: U: ]  ;; Now create the turtles and have each created turtle call the functions setup-cars and set-car-color
! c, r, y0 ^5 J  crt num-cars1 c0 g) }# B6 F
  [
5 `* E# G" F4 {8 F1 H' D    setup-cars
7 v2 h4 N0 {9 h7 l5 t9 W9 A. i    set-car-color% G9 r# Q, {4 A2 P5 f3 |5 {' s  U) f
    record-data
' y/ d, B3 h6 ^) Y: F  ]. U. ]' y% ~3 m! T2 }: i
$ L# {1 R( S$ `+ a; I
  ;; give the turtles an initial speed
: Q) D7 f+ Y$ _+ A' g  ask turtles [ set-car-speed ]7 P* t  x( t7 V+ X2 x

- \- ?! @  L" X1 y; q' V: _  reset-ticks% o& E: d- p( b, ~2 B
end
. @3 @  I7 a$ m' d: H' i3 O5 x; M# x  j! s
;; Initialize the global variables to appropriate values
) A6 B+ \9 C: r& Zto setup-globals$ k0 N6 \) }" n% S  l# @- o) w" D
  set current-light nobody ;; just for now, since there are no lights yet
9 p; d3 @0 I% p  set phase 0
, x0 a6 c1 H' ^, u7 n  set num-cars-stopped 0
" c' r. s) s- f, Z; G  set grid-x-inc world-width / grid-size-x( V$ Q1 Z2 t$ U& f4 t5 g* N
  set grid-y-inc world-height / grid-size-y% A) F: H, s' [; w; w+ c) Y/ D
. Q* H. Z/ A; ?2 u$ p) R, d) s4 g& w' x
  ;; don't make acceleration 0.1 since we could get a rounding error and end up on a patch boundary
; B+ g2 U7 j( O8 y7 M$ s  set acceleration 0.099
  q, q7 e7 y# h* i1 N/ {% T1 @end
6 p3 }: W/ I0 k; K5 V, Y3 u! E
! n" s! E0 t% {& J;; Make the patches have appropriate colors, set up the roads and intersections agentsets,1 ^% t+ B1 x4 [6 y6 m  F
;; and initialize the traffic lights to one setting
- ]) d$ {% r% h) b, A& Q# ~' J7 ]to setup-patches* a  U# c, L% b6 M, [* M
  ;; initialize the patch-owned variables and color the patches to a base-color" x5 U! h! M1 e7 V, v# O- E, L
  ask patches
) t3 i$ l5 U$ I% a: f  [* j$ }2 \* K' w1 ^1 K, C! o
    set intersection? false  D2 d: q2 w5 y+ e& \
    set auto? false
# N! d4 x' X0 P% J    set green-light-up? true
, \, I7 Y) O3 U$ H% Z( |# S    set my-row -1
; ^1 O, L1 ]; t7 M% y    set my-column -1
7 e+ R6 M: D( k! f    set my-phase -1. l5 H. T9 G& S1 z; `! F# ~
    set pcolor brown + 3
6 j" w: g9 C, V+ r7 E' B  ]) Z2 ^' v, ^; q0 l7 i

  A. E! q6 H1 W8 p6 Y6 ?  ;; initialize the global variables that hold patch agentsets: ?/ X9 W3 W, U0 L8 }
  set roads patches with
4 b9 ~! Z1 f9 J    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) or! a& L2 |7 E% D& o5 i' _. F
    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]
; j0 P% ~/ J+ }  set intersections roads with. I% k6 ?( j3 d5 p! B6 r
    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) and  \$ @9 F) ?* }- J
    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]% [0 O$ Q3 S/ Z  ?
* T! U; H1 G+ y. g. ~9 [
  ask roads [ set pcolor white ]
* r) r5 Z% n) F3 `    setup-intersections
( }7 |( t* z( X. P! ]! s) Wend7 A0 J- x+ |: \6 `* B
其中定义道路的句子,如下所示,是什么意思啊?
7 c3 j4 E7 E, K2 r& l set roads patches with/ W) R# W* ]+ A: }2 \
    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) or
4 P% B0 q$ a$ c! r    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]( @- U0 K: a1 V
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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