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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。5 l% f& r- c9 W  V5 W) t5 g, Q
netlogo自带的social science--traffic grid这一例子当中,! |( W6 D5 n3 {' j2 D
globals' b  i0 n7 t1 |) K2 r8 ?7 q( |
[" y* b% e- J9 ^! i4 b& |+ b
  grid-x-inc               ;; the amount of patches in between two roads in the x direction+ g1 O; O8 G) |
  grid-y-inc               ;; the amount of patches in between two roads in the y direction
- f- V/ i4 b/ e* R5 @0 P  acceleration             ;; the constant that controls how much a car speeds up or slows down by if
- V  V* \0 J: l& n9 p$ @+ Y                           ;; it is to accelerate or decelerate
# F( l  O4 `$ b* y- _  phase                    ;; keeps track of the phase( d+ g6 E6 l' D: f, `. g
  num-cars-stopped         ;; the number of cars that are stopped during a single pass thru the go procedure
) z' I; R4 j. z8 S( S, g" o  current-light            ;; the currently selected light
$ `' {9 ^8 L  U! o2 Z, E$ `( m: @/ ?; X# f  q
  ;; patch agentsets0 o- e* i' F/ X* j  Z" D; [
  intersections ;; agentset containing the patches that are intersections
2 l9 A9 F3 R0 X" J$ u+ ?" G# p  roads         ;; agentset containing the patches that are roads
6 s4 g" h9 X- k# []
) I( L6 m& w1 u% q
) H# C8 t/ O% o4 E# `1 _turtles-own
- K: l2 ~( Z, _[# h, U& i% I' p3 L: z' q
  speed     ;; the speed of the turtle% `0 n- s7 |4 v' c5 I
  up-car?   ;; true if the turtle moves downwards and false if it moves to the right
" X8 ~/ Z/ G& K* H  H6 |  wait-time ;; the amount of time since the last time a turtle has moved' F3 h" d8 X/ h# F. |& z
]
# `. u' D% O; \, |9 q
. Y. N. z9 j$ D  J0 Ypatches-own2 a! c* F- Q$ L  g' c
[6 L4 L! Z, q0 L% z. G
  intersection?   ;; true if the patch is at the intersection of two roads* h2 _5 d3 A% b' i( g
  green-light-up? ;; true if the green light is above the intersection.  otherwise, false.  B. [8 N# V  O! p& j9 g, I. b
                  ;; false for a non-intersection patches.
  d5 x. Z( _! N) K7 M. r7 ], O  my-row          ;; the row of the intersection counting from the upper left corner of the! x( a) L* X* f. }& E
                  ;; world.  -1 for non-intersection patches.: {5 ?6 K# U& [( I1 v
  my-column       ;; the column of the intersection counting from the upper left corner of the
2 ]2 j) L/ q* }* p: p                  ;; world.  -1 for non-intersection patches.' k9 L" {% t! [2 H3 ~/ o
  my-phase        ;; the phase for the intersection.  -1 for non-intersection patches.; `9 _5 w3 p5 D' e% h
  auto?           ;; whether or not this intersection will switch automatically.
% y' y: M% V. K* `: I9 D5 _. @1 x& [                  ;; false for non-intersection patches.
2 E$ Q0 D* j4 @# H8 Z" c]; m- z0 T/ F: Y0 Q
$ N4 }: G/ e# E0 ^

# s1 ]+ p; J! |9 }$ d- C8 c! x. D;;;;;;;;;;;;;;;;;;;;;;2 U9 @) f8 z- H1 |
;; Setup Procedures ;;3 I* n1 F( }$ u  ^9 B
;;;;;;;;;;;;;;;;;;;;;;
, S1 ^4 I, i( u7 w* E9 p' C5 Z3 m; [, w% b  W/ d: r2 I
;; Initialize the display by giving the global and patch variables initial values.
8 N, B) ~0 q$ D9 B) L( \+ j3 D& l;; Create num-cars of turtles if there are enough road patches for one turtle to
# Z3 U( j( c7 J2 S* K( O;; be created per road patch. Set up the plots.
+ Z( |' o2 H3 G$ @- Uto setup
) E. c( X5 r( g- v9 H, r# A  ca
6 v# w2 }4 @0 h0 l  setup-globals
0 W" D( s5 `, ^0 V
1 r: d' C1 q& n* m4 T# K  i/ \. Q  ;; First we ask the patches to draw themselves and set up a few variables/ J' Q3 ^+ w. p+ Y7 y
  setup-patches0 \# x. k2 p; q% D9 e- G
  make-current one-of intersections6 j5 k( E5 C2 ?8 W( L( U5 s& J& S
  label-current
' w. D' d3 m, T1 c9 |4 @( l: x2 s, @
  set-default-shape turtles "car"4 b; o0 m8 }5 o* e7 V
: N1 T# x" T7 u3 A: X# t6 z
  if (num-cars > count roads)5 @' {, J0 H: Z. o7 y
  [
% `1 o/ s" |) c( }    user-message (word "There are too many cars for the amount of ": C; L, d5 {3 Y. C* Y3 _
                       "road.  Either increase the amount of roads "( r/ f4 n3 @! z& T8 \8 ~
                       "by increasing the GRID-SIZE-X or "
+ L$ o( U& r  r5 H3 K                       "GRID-SIZE-Y sliders, or decrease the "
& ~. {7 w4 f+ Z  `                       "number of cars by lowering the NUMBER slider.\n"
* P0 J6 n+ ?4 j1 z: T                       "The setup has stopped.")
& c8 V. [, G) J+ a* {# S  a2 n    stop
, Z( Z- g% ^  A3 T9 R1 b, \  ]; I- T! Z1 G: d5 I$ k  r

" Z% _' P! r/ Z3 j4 P# y; P. V3 _  ;; Now create the turtles and have each created turtle call the functions setup-cars and set-car-color9 C$ }2 R. N0 R; _' Z: Q0 c6 M
  crt num-cars. G) w4 G7 L6 ^8 j  c! I
  [
9 W/ w( M, W1 {7 `( ~, G! i    setup-cars
. J- m4 {) ^* s8 w    set-car-color: [$ O- u& l$ e' ]5 W/ M
    record-data
) F0 @* O% K1 z- ?! |# u# m7 |  ]* S$ f2 e! h; g1 f# o

( d/ \4 ], @. g$ {  ;; give the turtles an initial speed
- f' M; n  ^" }  ask turtles [ set-car-speed ]
5 u9 R. h2 _8 Y: ~9 c) x3 z/ }) y" ?( ^8 }/ D2 w/ E+ g
  reset-ticks  O( S9 n$ Y" @& n6 {
end
! ?& X1 }; `) Z
, ]# k- @- D% D2 \3 s' j" s;; Initialize the global variables to appropriate values
" o' D- e  M) j' Oto setup-globals% @; X* x/ V+ s) T" z+ t4 [5 y9 {8 i
  set current-light nobody ;; just for now, since there are no lights yet3 h! |" c/ F8 P- c  Z
  set phase 03 J7 j: Q+ G9 e. s1 a. K# D
  set num-cars-stopped 0
. |( r9 H7 r$ a2 i  set grid-x-inc world-width / grid-size-x
4 c# B9 S5 u+ u! k) u" X. W( l  set grid-y-inc world-height / grid-size-y& Z  `& \0 E8 }( N; ]

# x5 ?3 F# e7 a  ;; don't make acceleration 0.1 since we could get a rounding error and end up on a patch boundary
5 T- c" b, q7 X  set acceleration 0.099
  ^8 O3 ~8 M3 u! }8 w7 J: Hend
6 f+ X. q( K7 z, h/ K6 j8 r5 `, O/ D0 J, _
;; Make the patches have appropriate colors, set up the roads and intersections agentsets,' v, ?: m2 \- m" a0 r2 r4 Q
;; and initialize the traffic lights to one setting
7 I4 ~$ k  ^* cto setup-patches  t; f' v% e  z: Y7 x) C8 g) r) @
  ;; initialize the patch-owned variables and color the patches to a base-color
8 y0 `# f% w0 j! f$ r' \; W8 p  ask patches1 k" B4 @. h. F. n. L3 ~, j
  [
: a: M+ D. n1 E    set intersection? false7 _5 j/ y! R% g2 ^  i. v
    set auto? false
: D- @5 X0 l+ u+ x    set green-light-up? true
, s6 ?) j4 z, \2 f) L# L    set my-row -1; n9 f$ T: }5 y1 o2 K
    set my-column -1
& U+ r% L6 Q- o  h0 p) E% o6 U    set my-phase -1* i; d/ j7 e- A. e
    set pcolor brown + 3
# P/ Z, K# Y2 O! d; S0 a  ]% M& T; B$ p- ^  {) P! F

( r8 z% Y* q1 O  D& m: C: A  ;; initialize the global variables that hold patch agentsets
. J" K: e6 e2 r9 L! t  Z1 y  set roads patches with3 Y5 |4 g7 M0 a1 m; D# v
    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) or1 x) R0 D$ y) Y9 D7 y) N
    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]8 }  e' h8 z9 I+ {/ g2 t
  set intersections roads with0 |# |" Y* C8 M& x7 I
    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) and3 D0 u: y* s, J4 W. t& u& r
    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]
% W) O6 Y  B6 ]- u. L1 u+ n8 J6 |# h* Q$ q# R
  ask roads [ set pcolor white ]* N- s) W, j7 {2 Y
    setup-intersections
: s. Y6 N' ]) @0 Q$ H" ^; Vend
& y. R6 f/ z' n. I, T0 A% R其中定义道路的句子,如下所示,是什么意思啊?
: j0 K/ P; M9 `) W7 f* E set roads patches with4 a8 l& p" o" \9 w( i. H8 y
    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) or
6 F1 i2 x7 Y8 k6 k, p    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]6 }* P1 y& n( r& r) Q; Q
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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