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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。- W9 `! w3 u( l4 P" w: C
netlogo自带的social science--traffic grid这一例子当中,
+ x, X& z5 b% p6 f+ ?# dglobals
3 q3 u$ o- k# D( `5 {[! p9 R: m5 Y; k2 Y$ {% i  y
  grid-x-inc               ;; the amount of patches in between two roads in the x direction1 a$ v2 d" y3 t. R" Y
  grid-y-inc               ;; the amount of patches in between two roads in the y direction
: S; F) e  D0 E. F0 i3 e  acceleration             ;; the constant that controls how much a car speeds up or slows down by if) [8 `! V4 X+ @
                           ;; it is to accelerate or decelerate
5 B: s9 O- g7 z0 r; d  phase                    ;; keeps track of the phase" x5 T6 |3 y+ d; z( G; t
  num-cars-stopped         ;; the number of cars that are stopped during a single pass thru the go procedure
4 E! q' K; D$ }( \5 V  current-light            ;; the currently selected light" i7 N/ l' v- c2 m. l0 V
; X+ P2 o/ L. m1 ~% N* Z* B$ j
  ;; patch agentsets
) P' o$ ^' _- L6 R3 p; P  intersections ;; agentset containing the patches that are intersections9 J1 x* D; n/ k' ?
  roads         ;; agentset containing the patches that are roads" V9 }  b( X' T. y* z. r
]
; [2 j  y; I/ x$ i& F4 |
; }$ R, ?0 }; g) {1 ^# e# h9 B+ y& d0 rturtles-own
4 M0 R2 u- N, x- v5 `$ x8 y[$ R) l2 P4 o5 Y
  speed     ;; the speed of the turtle
5 D. B7 E7 m; Q3 P6 J% T  up-car?   ;; true if the turtle moves downwards and false if it moves to the right
/ A. J5 E  K1 F/ P  wait-time ;; the amount of time since the last time a turtle has moved, ?" d# N1 D- X6 j
]
  \( L% r/ w. G" v6 B
" u; n$ g3 ~8 F4 L& k$ d8 ipatches-own
5 q5 j) a1 O- ?[" V' @/ ^' L7 t3 C. r* Z, b* p' n
  intersection?   ;; true if the patch is at the intersection of two roads; m  i! n6 j: b3 J0 M1 a
  green-light-up? ;; true if the green light is above the intersection.  otherwise, false.
# D( n( ~- d1 t  V# s. Y                  ;; false for a non-intersection patches.
! D5 Q; X9 d& c/ |  my-row          ;; the row of the intersection counting from the upper left corner of the' V" T$ X* m, }. E9 H
                  ;; world.  -1 for non-intersection patches., X1 v4 A* q5 k( a! P/ ]/ e  {1 H
  my-column       ;; the column of the intersection counting from the upper left corner of the6 Q+ i  k( E$ M+ T
                  ;; world.  -1 for non-intersection patches.
9 e$ s4 p8 Q' s! @& a  my-phase        ;; the phase for the intersection.  -1 for non-intersection patches.
& Q6 q' h$ m; C2 q/ j  auto?           ;; whether or not this intersection will switch automatically." T1 |, z0 L: `
                  ;; false for non-intersection patches.2 U; n5 K- w: ]0 I  z) v
]+ G8 d1 d4 u! }9 s8 t6 D, t6 m
) _3 F+ d& l$ S& X# W

) {4 l1 ^$ P- ?* d9 s6 e;;;;;;;;;;;;;;;;;;;;;;) p9 @# E0 I9 s0 y9 B9 S+ C6 ^
;; Setup Procedures ;;
& _4 A7 N2 M+ u" X5 y4 ~0 c+ Y;;;;;;;;;;;;;;;;;;;;;;
" U8 O4 J. I$ v; ~/ q
" n1 i) ^% [; s/ Z2 p: [;; Initialize the display by giving the global and patch variables initial values.3 l: N' E' }% |0 ~, I- f1 q
;; Create num-cars of turtles if there are enough road patches for one turtle to
4 v) q9 B. y- O& x. n: c. g+ S;; be created per road patch. Set up the plots.
" C# S1 c7 M( }$ y9 l6 lto setup
1 P: L4 P5 G. U2 [  ca
" {- G  o. r. Q  setup-globals
5 O( G& n8 Q. x8 P" m) k' ]% p% Y$ U& j. V! {2 X
  ;; First we ask the patches to draw themselves and set up a few variables$ d. m0 y7 w( r0 q3 n4 M' s, [% i$ u
  setup-patches) l% W! \# Y: g. n
  make-current one-of intersections! R+ F+ D! ?+ _6 K
  label-current* j1 I2 _; [1 _# G

# K: W3 j, v$ ]* C- o# v8 K  set-default-shape turtles "car"! _5 ?5 |3 A2 E" E6 f- R1 F8 U( c
  n5 V" k4 |5 m
  if (num-cars > count roads)/ s) ?% g1 |$ q" {; T
  [
: o0 {3 \/ ]1 R( D, F" B; B    user-message (word "There are too many cars for the amount of "
! {0 t$ f7 R( f- U* O, ^                       "road.  Either increase the amount of roads "
- e& |9 b+ L2 l2 r) {                       "by increasing the GRID-SIZE-X or "
* E! }, q; s  T) q                       "GRID-SIZE-Y sliders, or decrease the "- g7 ^& ^. G8 q6 f
                       "number of cars by lowering the NUMBER slider.\n"# _/ l7 b  ]: `
                       "The setup has stopped.")
7 J) H0 ?( Y  |; N$ l    stop
( V$ f0 ^! A( Q/ P3 a9 E- z5 z* E& ]  ]
0 k8 i8 @. |% I6 ^3 Y- E5 y3 o5 s# D( f9 O2 p! U- V& ~4 {
  ;; Now create the turtles and have each created turtle call the functions setup-cars and set-car-color$ \6 K) z" k1 T4 r& |; o
  crt num-cars
! W/ z( O& t8 w- q* a  [( A& X; Z. j$ q4 A+ O
    setup-cars2 L: o/ n7 c7 l1 l
    set-car-color  P) j( Z3 A  P( ~9 u) `3 d
    record-data4 q0 r/ z2 \: s+ v
  ]) ^" ]* F! ^, E: O. [
8 n' \4 h8 l0 v4 T  {( v
  ;; give the turtles an initial speed9 I3 E# d. ]; L, J4 ^+ t% U
  ask turtles [ set-car-speed ]0 B2 o  |7 Q* @4 r  C
6 G$ \4 E+ j" I7 z
  reset-ticks
* J- z5 R" B5 W4 }6 Kend5 a  G. H4 c- _; }2 \+ C
# `% m, |# E% Z$ N: {2 a3 O& }
;; Initialize the global variables to appropriate values
( Y1 l1 F1 i, x% Gto setup-globals) `3 z4 V1 G6 W  e  W
  set current-light nobody ;; just for now, since there are no lights yet
, J& K) v: X% s& `7 o. ~( h  set phase 0
" v: U, t2 V% U3 A  set num-cars-stopped 02 x: I+ M9 a7 B  k
  set grid-x-inc world-width / grid-size-x
* D4 p7 H/ |! Y5 {: t6 {  c7 W  set grid-y-inc world-height / grid-size-y& F) E9 i# M+ o

- U" T- i7 Z# h* L! W& L  ;; don't make acceleration 0.1 since we could get a rounding error and end up on a patch boundary3 [8 u  p3 \9 x9 p  M& U
  set acceleration 0.099: E4 B3 F: X* e4 ~
end- d9 S) \0 S7 a, O# ~; v9 B

- r4 o3 o3 v& b5 l;; Make the patches have appropriate colors, set up the roads and intersections agentsets,8 D! [; p1 R/ T6 j9 S4 T
;; and initialize the traffic lights to one setting
2 X+ S, E. k9 F$ Mto setup-patches9 v8 X! h9 k1 V4 i0 g2 [
  ;; initialize the patch-owned variables and color the patches to a base-color
8 |+ p+ S9 c* o* i7 H5 A/ b  ask patches
2 Y( q/ h3 `3 ?/ e8 }, J  [
- ?! Y* d4 M% s- Q    set intersection? false+ Z" b  J) W  {. G
    set auto? false
' _: r0 c$ p2 x5 J7 U    set green-light-up? true( L  Y8 s2 f5 x, c2 r
    set my-row -10 y7 K7 e5 K9 b# l! j3 a
    set my-column -1
" C# P2 b% ]- Z5 i; T; n    set my-phase -1  F) ]$ e1 L. e  g& Q1 R; E
    set pcolor brown + 3
9 M7 t. N2 n+ w  ]& O. g! Z  J1 a5 j( c9 B1 y- l3 u9 m
) M! b/ V( B% L4 s. Q
  ;; initialize the global variables that hold patch agentsets
( e' l+ s+ Z1 N  f* m) r6 K; b( x  set roads patches with3 h) U; ]7 L& X! O# o+ t; n/ }0 p& W
    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) or5 U7 E6 |% D4 v4 J, t( Y6 M& i6 e
    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]
' I3 u, ?! }; d, H  set intersections roads with
' }) X3 L. v: I3 R  Z: Q    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) and
, w( ?! s5 Y# T9 `. F    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]
2 j$ J, J) N. |/ |% }' x, J% a4 }0 }9 i
  ask roads [ set pcolor white ]) }: S. L% z: k; _
    setup-intersections
& U3 s- J; @; C2 ]end
; V* K) C% e2 U3 t; l其中定义道路的句子,如下所示,是什么意思啊?
5 n( f  V# s) k, G8 E set roads patches with
, X; H* G4 t( z    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) or$ ?) a+ S) {/ x3 h4 C3 h  c  f. z
    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]7 i2 l; A. K3 ]" P3 ?
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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