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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。& ?7 K+ [" W7 I1 Z/ Q7 S! Q
netlogo自带的social science--traffic grid这一例子当中,
. I1 t- s0 k  F* Q- g, ~globals
) |0 X  I6 _' w9 }" i% f& T. j8 i1 l[
  M; \% `# ]3 l. X* ]8 e6 P  grid-x-inc               ;; the amount of patches in between two roads in the x direction, S+ j9 S$ c) d1 ?
  grid-y-inc               ;; the amount of patches in between two roads in the y direction
' \0 a8 c( m6 y' o5 k  acceleration             ;; the constant that controls how much a car speeds up or slows down by if' O' i) R. q  Q' a; S
                           ;; it is to accelerate or decelerate
0 ~% J' b2 R! U: A  H5 e1 O! U  phase                    ;; keeps track of the phase  E$ D7 E; ?' b  ?$ a& F0 ~" ?* T
  num-cars-stopped         ;; the number of cars that are stopped during a single pass thru the go procedure2 q% a& c! I; v# E- r
  current-light            ;; the currently selected light3 ~. y0 i$ i1 ]1 E0 x" n
9 ^$ {3 x7 w7 a$ B; m
  ;; patch agentsets# w, X6 O( W1 ^, ?7 ^# P/ n
  intersections ;; agentset containing the patches that are intersections; a$ \/ \( ]/ U- B
  roads         ;; agentset containing the patches that are roads) }  b% G" \. g6 Q6 V8 p4 S
]
: `* x; ]5 v2 ]
" z6 j4 o6 m7 N9 A: A" fturtles-own0 J8 T& T! J0 b
[
, A+ j) g; ^) p* s9 B# ~( e! B  speed     ;; the speed of the turtle
6 G( m% ^6 F) \: a5 \  up-car?   ;; true if the turtle moves downwards and false if it moves to the right
" ]3 X) N0 F& I0 E5 p6 @  wait-time ;; the amount of time since the last time a turtle has moved
. W$ S+ ~+ v$ z) }& y6 F+ Q6 r7 q]( w# _- d% M# |. `! M
0 z$ I+ s9 N1 w3 Y
patches-own
- K4 R: ]3 e0 v$ K0 }[* @6 i# Q) O5 ?) V+ ?$ c, b1 T" n: W
  intersection?   ;; true if the patch is at the intersection of two roads
) y2 l# R5 H- u! Z& }  green-light-up? ;; true if the green light is above the intersection.  otherwise, false.
9 ?9 Q& ?0 V/ s% |4 E! z- A, C                  ;; false for a non-intersection patches.9 f- E. P; R* c" p
  my-row          ;; the row of the intersection counting from the upper left corner of the, w* @' V6 g, O* B5 }
                  ;; world.  -1 for non-intersection patches.
) |6 W( Z# ^% D( a0 t' j& `  my-column       ;; the column of the intersection counting from the upper left corner of the
# I1 x; v# A  f3 Q& E                  ;; world.  -1 for non-intersection patches.8 d" X% M4 U! a; ^6 {( f+ \1 P1 h
  my-phase        ;; the phase for the intersection.  -1 for non-intersection patches.4 S7 g0 {- }- ]+ N) O
  auto?           ;; whether or not this intersection will switch automatically.
% [8 e" N+ Z$ K2 {, l                  ;; false for non-intersection patches.
* I% P4 X9 H2 F9 j5 {]
, X& G) F1 I) {  p( C2 ]& d$ S  L: \; N6 |; B
0 [2 V; u0 ?6 C4 w* ^! p
;;;;;;;;;;;;;;;;;;;;;;) z5 N1 h8 g; f' p# v
;; Setup Procedures ;;
, L1 H$ L2 ?8 n7 i% }7 e;;;;;;;;;;;;;;;;;;;;;;) J3 @$ y9 R! |" n9 o  K% }
3 y! ]; Y3 C& t. ^# _2 a! O
;; Initialize the display by giving the global and patch variables initial values.
; \, S) b9 w  v# C9 T( }+ p;; Create num-cars of turtles if there are enough road patches for one turtle to
# C$ j' ^0 e8 g7 E$ o;; be created per road patch. Set up the plots.
/ Y) B, c# j) }4 y, Uto setup* U* G, j0 P, @  x# f
  ca& c2 m+ `# H+ B# M
  setup-globals
$ c/ F# Q; V) r7 i/ V2 c' d, ~. Y/ g
" g- r# C9 e0 G% }2 d7 [8 m7 m  y  ;; First we ask the patches to draw themselves and set up a few variables" G- P5 ], e: |, v) K9 G; z
  setup-patches9 i( g# Y9 d( _9 c7 G9 y# n4 S$ H, [
  make-current one-of intersections8 U; y& T. J( Z4 S
  label-current- x  o. S3 }2 Y/ _/ b0 Z1 ^. f4 q

8 H, |( ^5 U* _/ A( Y  set-default-shape turtles "car"( k( x4 {9 P/ }! |) }  Z, n

6 N# S- x  T0 i, E1 M4 R  if (num-cars > count roads)
, ]3 p, x, l8 f( x8 r/ z  [
# L# f( E) {& P    user-message (word "There are too many cars for the amount of "* P2 v  s' R1 q7 m
                       "road.  Either increase the amount of roads "
6 V* E6 z3 @1 x( b7 y                       "by increasing the GRID-SIZE-X or "# I- e- N/ T* Q
                       "GRID-SIZE-Y sliders, or decrease the "
( @, R9 }. U. O  C: a  O, L- l                       "number of cars by lowering the NUMBER slider.\n"
$ q; C- p* w4 w! z                       "The setup has stopped.")
& h+ \7 C; W( G4 o    stop* n2 }2 `; R5 N+ \0 R  ~  d
  ]
* u( u  [% U2 i& N: j* `$ b( ~( i9 Q$ v' M% w& {; \  u
  ;; Now create the turtles and have each created turtle call the functions setup-cars and set-car-color
- Y2 Z8 V5 j  k  crt num-cars1 x! E) b& m, n
  [/ _* f0 ?, c) s% s, f6 b$ }! H
    setup-cars
$ z4 e* i8 A0 h$ P; x    set-car-color/ S" ^' ~% i- m( t
    record-data: t3 O7 S; g. w% Z1 c9 C$ ^0 _
  ]* E& q" g7 e( J% }, ^
8 ]* ?; Z" m& |& q8 q7 f
  ;; give the turtles an initial speed2 v% m% |  E  t( o# Z3 Q7 C! M
  ask turtles [ set-car-speed ]3 w( ~4 o8 M- W0 B

& B+ j! q1 {( i: O  reset-ticks' z* u5 u# m: t( L; J9 b
end
5 R- x: y: l% i8 |
4 v8 w; U& K8 M) ]6 I) ]1 S;; Initialize the global variables to appropriate values
  `* [2 E2 S/ Y! g6 n+ tto setup-globals8 I0 V2 a6 H1 b  m  a$ Z7 Q( b
  set current-light nobody ;; just for now, since there are no lights yet
% N2 x: |1 T( }; J8 r7 c  set phase 0# `% M8 D0 z8 h( P
  set num-cars-stopped 06 @8 m, U! j$ @- U& e# K, H
  set grid-x-inc world-width / grid-size-x- q% h7 v* q( l9 V, v9 [
  set grid-y-inc world-height / grid-size-y
9 b1 f$ M9 ^) y; m2 a
9 R! I# U9 a: a' ]. b6 m  ;; don't make acceleration 0.1 since we could get a rounding error and end up on a patch boundary
1 y$ ~1 u4 D7 E. a6 U0 {% L# d  set acceleration 0.099
% y# T8 Z0 ]6 Rend8 r+ U( x+ Y# M6 h" P# o1 `- D8 X$ e
. S6 a. D  z* s0 f/ A7 m
;; Make the patches have appropriate colors, set up the roads and intersections agentsets,
% ~: c2 h0 E9 T# e; t% x0 };; and initialize the traffic lights to one setting. o0 W6 c) V* s0 i$ g3 W
to setup-patches, @6 {7 P. i' b! T
  ;; initialize the patch-owned variables and color the patches to a base-color" q: ^& H# O+ ~
  ask patches: S& j( X. d- h. P; b& H
  [
; x" m% [" N8 [: Z) O5 k4 J    set intersection? false
3 E/ s; G6 C0 L5 R    set auto? false
5 V+ B5 g$ a. Y& W( c    set green-light-up? true. l6 g# R  w/ s  m+ {' i: l
    set my-row -1
, O4 ~, Y1 w5 ~/ x/ _1 N    set my-column -1" c) K( {& J3 Q
    set my-phase -1
8 g) ?- A' a( n    set pcolor brown + 3- R2 B6 P4 ]+ Q7 u% E7 `
  ]
& {9 K* X& j' ~4 f  J; \! W3 Q* w8 j+ B7 V" O" I
  ;; initialize the global variables that hold patch agentsets
+ W3 D0 E2 C: M/ n/ C  set roads patches with
  s3 |* L0 q  F( R    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) or4 S! d; W' p/ e" {
    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]' q$ T+ H7 e+ f
  set intersections roads with
" k/ y% m6 I7 b5 Z4 y. C' T+ O. Z4 C! Z6 s    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) and
+ G  q" ?# z2 ]! d. t/ o& Z    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]
. x, Q/ Q0 ^$ C$ R1 ?: O* w0 z& V6 m& S1 K
  ask roads [ set pcolor white ]+ w" O" Z9 e2 W* P4 ^' O$ A
    setup-intersections
6 u% \' x+ U. N' \9 s" }end8 N2 d+ C$ F4 ?, x3 C
其中定义道路的句子,如下所示,是什么意思啊?) k4 [8 i# @. {. e
set roads patches with
9 \& M% }0 ]) @7 }    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) or2 X( `6 @, X, \1 p
    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]: m" G' d' G4 y7 D  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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