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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。- S$ _- y+ I$ {+ `
netlogo自带的social science--traffic grid这一例子当中,
3 ^6 ]2 P9 n/ T2 M. [0 y$ eglobals: V3 x! D" a6 j: ~5 Z1 g/ J
[
  X. W/ N, j0 x' R5 n! M  grid-x-inc               ;; the amount of patches in between two roads in the x direction$ _0 \7 u: l- T, s0 `
  grid-y-inc               ;; the amount of patches in between two roads in the y direction+ v8 @% B- P6 ~, g4 C+ ?& ]& ]
  acceleration             ;; the constant that controls how much a car speeds up or slows down by if: h2 a. f$ ?3 K9 ?' C+ ~" P$ t
                           ;; it is to accelerate or decelerate( k' F6 Y3 i6 ~  A( x
  phase                    ;; keeps track of the phase" K) @- B) V9 d8 f5 w
  num-cars-stopped         ;; the number of cars that are stopped during a single pass thru the go procedure! g" v7 ]3 D% n
  current-light            ;; the currently selected light
9 `% v- p5 F' V" [% G  `# p
; O4 M% E0 @+ w  ;; patch agentsets3 a: ?+ x, z/ |& F
  intersections ;; agentset containing the patches that are intersections
' i. p( }# F3 w8 A& Z& G. E# I: @6 w  roads         ;; agentset containing the patches that are roads
. {* ]# ]0 `% }( z# F6 C5 |% a]
! d* N9 g$ @( j2 H
( {8 X' |; |' M7 c% Kturtles-own' u( D4 `$ B6 x) T' d
[
0 I1 {) C* i) l! f. v/ H& r* p5 B  speed     ;; the speed of the turtle
( J' K" w( t; I. k! i4 e* X' j  up-car?   ;; true if the turtle moves downwards and false if it moves to the right
9 _0 x# a; [! v, G  wait-time ;; the amount of time since the last time a turtle has moved5 x* ~5 e" f  J) N, Z! ?" m8 p0 ^
]* j& k) J) Y8 O3 Z- r( ?# n: ^4 T: n

$ b8 f" _. Z1 o/ Kpatches-own' ]! _: m! A2 H
[
. Z. [7 t  f9 H  intersection?   ;; true if the patch is at the intersection of two roads) x: X  m( N! z2 l/ g& s- m
  green-light-up? ;; true if the green light is above the intersection.  otherwise, false.
4 l- \' N, [2 G7 C                  ;; false for a non-intersection patches.& _& r6 i3 a" P+ D1 ?$ Z
  my-row          ;; the row of the intersection counting from the upper left corner of the
8 ~; C+ F2 p- d8 |8 p+ M; _                  ;; world.  -1 for non-intersection patches.! w& q% ~/ e+ I6 m6 J
  my-column       ;; the column of the intersection counting from the upper left corner of the$ Y1 f8 q! c- G5 W* z" Q3 z1 V- i. H
                  ;; world.  -1 for non-intersection patches.
) g, r* x+ p/ m- m  my-phase        ;; the phase for the intersection.  -1 for non-intersection patches.
  A1 Q3 L! y$ n' r' D# S- n( G, ?  auto?           ;; whether or not this intersection will switch automatically." d+ L5 W; h, r8 w
                  ;; false for non-intersection patches.1 O6 D- O2 E% Y6 F
]) l0 C7 y3 M. _; B% i( r

8 s2 i' ]. t- Y7 ?& ?5 ^
) e/ u* N) i; n" |! b;;;;;;;;;;;;;;;;;;;;;;( d3 w5 D, W' D/ z# q
;; Setup Procedures ;;) I9 {* f) V; ]' m/ |* g) ~
;;;;;;;;;;;;;;;;;;;;;;
% c* V. y& |; j1 m) e' N' R9 i; q) @
;; Initialize the display by giving the global and patch variables initial values.' R# l: S* _9 I6 g4 u( W  u( I9 q
;; Create num-cars of turtles if there are enough road patches for one turtle to
+ r7 S! T; m1 Y+ |+ u" |2 p;; be created per road patch. Set up the plots.8 F" }1 Q6 b- Y7 e: [. P
to setup
( e) o: D) w5 a  c" l, P0 ^2 p1 Y  ca
+ u/ m6 Y: t, L1 g7 j  setup-globals, U+ E' {! P' ]  [

7 C; O5 c! i+ K) j  ;; First we ask the patches to draw themselves and set up a few variables  F6 M. {$ i1 ?0 Z: |
  setup-patches
7 N0 x. _' T8 c: Q5 k  make-current one-of intersections
7 C5 E# W4 r7 O; Z  label-current
# b+ x8 [# U; ^, L! v' \, W, B% p- e4 F; I& U  L4 v
  set-default-shape turtles "car"$ j" }: v1 S2 R, Q0 r) J1 Q! V

+ S# K( p9 f1 o* o. }  if (num-cars > count roads)- A1 A) q2 P; y. v' {
  [) d- ?4 {, a' s2 l& D& T
    user-message (word "There are too many cars for the amount of "
5 F( n6 }+ ^; t/ ~                       "road.  Either increase the amount of roads "; J' ~& D4 S8 O4 f6 ?5 s
                       "by increasing the GRID-SIZE-X or "9 [7 L3 z8 W) C, u5 f, Y" O" S/ m
                       "GRID-SIZE-Y sliders, or decrease the "
6 ]& n; Z- D8 e4 h2 ]                       "number of cars by lowering the NUMBER slider.\n"
- V7 }" A# x9 g. K" [* i1 g                       "The setup has stopped.")
. E. u' J5 c2 d. n$ W- Y    stop" y; Y3 `4 r% n  x/ M/ z
  ]
- {+ L* A; Q; K  c% O$ `% F) B$ e* }. q9 S4 D6 A; V; a( E% Z5 R- J, d) j
  ;; Now create the turtles and have each created turtle call the functions setup-cars and set-car-color2 |. I1 A( S. Q8 O
  crt num-cars
5 Z8 c* o4 j: Q; v  [
. y' S5 |4 l$ V& b( v# ~. y, d    setup-cars0 O2 a2 h, b; y8 N: p. {5 T
    set-car-color5 v1 Q% I5 z' v7 i/ C
    record-data
+ h7 S' h  T7 D# z  b  ]% F3 r+ F7 T; d" j: Y. d

$ U( P  L# S: ^, ]& a$ p; J* a  ;; give the turtles an initial speed
  A. ~6 @( k! E& Z$ U  ask turtles [ set-car-speed ], P/ r& L8 b3 J5 g- \4 W

1 j' }( w' v: `$ ~9 i: j  reset-ticks
) F3 P7 N7 o  ?# q' pend, [( j1 G- X+ Q; K
" X, V  h- P) _4 }4 S, v. X- X
;; Initialize the global variables to appropriate values
, `$ n! a3 v$ V$ A: w( ~$ nto setup-globals
% B7 R8 x4 f) |4 ^; A$ p4 ?  set current-light nobody ;; just for now, since there are no lights yet
8 ^+ G1 H" O, M9 z6 x2 f, U  set phase 09 Q1 Q  h) J& v* S+ U6 p8 ^- L
  set num-cars-stopped 0
, F# ]' _6 T. I2 d/ T  set grid-x-inc world-width / grid-size-x
/ C1 {9 k: {4 L6 ]+ M7 |  ~  set grid-y-inc world-height / grid-size-y
6 n1 Z$ H. W) E9 _0 i- r- w$ c. d3 h% k2 i6 s$ U+ c! e0 G
  ;; don't make acceleration 0.1 since we could get a rounding error and end up on a patch boundary3 ^) B' M; j2 S" D
  set acceleration 0.099
: |6 P, A9 ]4 y& zend
7 b: T/ p: z# c+ J! U; v( N; Z$ e3 O1 S/ Q' \
;; Make the patches have appropriate colors, set up the roads and intersections agentsets,9 |, T# Y% B) C" j% U/ l
;; and initialize the traffic lights to one setting7 a& j, O0 _6 J/ m5 d5 I
to setup-patches: w+ B" l& [+ n' K/ h9 ?8 C- G. P4 s
  ;; initialize the patch-owned variables and color the patches to a base-color& l. F- x3 c3 `/ g/ K. |
  ask patches( j8 _/ O! W4 p6 v0 e$ }$ B' q
  [2 D$ u4 t; Q  `  j3 l/ Z
    set intersection? false
8 s+ ?4 j  k( d9 x$ ?+ O    set auto? false
( A/ a  B( z# C2 J$ v    set green-light-up? true# g/ W- s! g4 w# K
    set my-row -1: S) S6 Z" h. n: }; J  F4 N; I* e
    set my-column -1
+ L3 V8 m* D; [% i6 b    set my-phase -1
% Q0 b, y3 y+ z/ }% S    set pcolor brown + 3
" E3 \6 S' y8 F$ s2 u9 ^1 e  ]4 X9 U: o+ \. k; x4 Z3 K( G7 @" n
! ~5 ?) ]% ^$ v, D2 n
  ;; initialize the global variables that hold patch agentsets
( h# V4 {# \0 M' c- U  set roads patches with- K, a/ T6 n2 n6 \2 _4 v
    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) or
" r( O8 u' P7 j. H0 f    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]
( M6 B& ^& g/ }5 I2 S1 k  set intersections roads with
& Y- z+ N- h2 b% G1 v# o, O% @! u    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) and
2 P/ N1 O: J6 r0 T    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]
7 m# R3 p* E, u% h
& C8 p5 O" W3 e. P! [# l  ask roads [ set pcolor white ]
: c! b" k! w' w2 N+ q    setup-intersections) J& Q& E# L' ?$ X
end6 \- i& G( F3 y4 ?% m: C
其中定义道路的句子,如下所示,是什么意思啊?
/ N2 d; n/ H+ S: c$ I set roads patches with; {3 F; B$ ^6 ^# z& _& G# X  A* d
    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) or6 X2 |+ G: E$ t1 {
    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]* g2 j  Q4 ~* U$ U! j# B0 L3 x
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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