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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。
& `  T8 [. N( r" X* b4 f& W% H/ J, l$ Anetlogo自带的social science--traffic grid这一例子当中,
+ c3 Y3 M" Y' h; f3 Lglobals6 o' D! A  N  Y9 \+ l- J* g/ T5 c
[
* \( w: b0 \& `* m6 m  ^0 T  grid-x-inc               ;; the amount of patches in between two roads in the x direction, s5 i: c- H; m+ e8 s2 w* u$ [
  grid-y-inc               ;; the amount of patches in between two roads in the y direction
' C4 Q. H( X* y. q# K# |3 |  acceleration             ;; the constant that controls how much a car speeds up or slows down by if3 j8 p# C4 ~' K$ O8 @9 g1 l. ?: h, Y" e
                           ;; it is to accelerate or decelerate
/ m  t8 {, }( r. L' Y: ?' k: B  phase                    ;; keeps track of the phase: A# s" u5 k, D2 ^8 s8 ]' O) T
  num-cars-stopped         ;; the number of cars that are stopped during a single pass thru the go procedure0 E$ r4 e7 v+ X' H, w
  current-light            ;; the currently selected light
- o; Y: {) W% H0 d- `3 w+ b" e% e! U4 h5 O- U7 Y. C& k
  ;; patch agentsets
. s5 R9 U  M5 s  _  intersections ;; agentset containing the patches that are intersections2 d+ y4 D0 h+ O; _# Y! |% x% \7 l
  roads         ;; agentset containing the patches that are roads
) v5 X! q: l& j) o: K]7 n# {1 [  c) A
' B0 Z2 r) T) T
turtles-own( S' J, _2 ]# j3 I" U: |
[4 ~# e) D. A: |
  speed     ;; the speed of the turtle
1 q) a7 Q7 @" f- G. P  up-car?   ;; true if the turtle moves downwards and false if it moves to the right
: c& l7 ]' c/ a4 f6 [  wait-time ;; the amount of time since the last time a turtle has moved6 ]; I1 {' \$ V: l' ?1 m
]
3 L' b. y# x2 r" M5 Q# f+ K; u
& i  Y1 B) |. }patches-own
1 x0 B  A0 Q& H$ I7 y# r[7 t: ~2 w, o) l8 ~5 g
  intersection?   ;; true if the patch is at the intersection of two roads- }) h3 L  Y& m7 n
  green-light-up? ;; true if the green light is above the intersection.  otherwise, false.
' ~# t  y8 ]8 a                  ;; false for a non-intersection patches.
% X9 U+ W$ \  b/ W& d( G  my-row          ;; the row of the intersection counting from the upper left corner of the
( ^! F/ h8 _3 u                  ;; world.  -1 for non-intersection patches., N7 A5 q7 x1 \7 _+ K. V% _
  my-column       ;; the column of the intersection counting from the upper left corner of the
% n3 H2 K8 I; M8 Y2 l2 B                  ;; world.  -1 for non-intersection patches.
# D" B7 h2 C+ r* ?# B* n  my-phase        ;; the phase for the intersection.  -1 for non-intersection patches./ h; L& B5 x1 K' W) U
  auto?           ;; whether or not this intersection will switch automatically.
! @" d- G) y! o6 o" `                  ;; false for non-intersection patches.
: a) g: ?" X# j6 T  E]
$ }. P8 I( L* o; |5 m6 ]# M) S0 p4 p& o+ ]: s

  |5 l* w$ t4 P) J;;;;;;;;;;;;;;;;;;;;;;
6 |$ r. R7 Y4 q" [$ ?;; Setup Procedures ;;3 h7 O* B' u& w& r, }, h! J! I4 w8 }
;;;;;;;;;;;;;;;;;;;;;;) p4 {  P1 H- m

' `" P) Z" Y) y) ?* \;; Initialize the display by giving the global and patch variables initial values.# ^  w* k, O( ]4 f/ N
;; Create num-cars of turtles if there are enough road patches for one turtle to
: A3 [( M/ K) w1 j; e! `: g7 w;; be created per road patch. Set up the plots.0 i9 p; F9 K% W& J$ B: K; ]
to setup
7 U' f0 a8 _/ _0 i, O+ s) N, p4 j/ p  ca
$ {! a$ ~2 R+ \0 K1 ^1 Y  setup-globals" S+ t6 U# d" G
4 t; a6 @) q- F
  ;; First we ask the patches to draw themselves and set up a few variables
. q/ X  h  b7 ~8 v  e  ]* {# Z  setup-patches" i/ Y& z% D  z  h
  make-current one-of intersections( z* s" n1 b/ z, O& c
  label-current
5 S) `; R' J5 j; ~2 A" F
! p; x$ {: \1 {+ o0 S  set-default-shape turtles "car"
/ g) R( |& C* L- s6 `8 e5 P
6 E3 P5 F* L# z9 z# N% |  if (num-cars > count roads)0 g/ |5 S4 P; U0 s
  [1 j2 f) \/ o% G5 O4 ?
    user-message (word "There are too many cars for the amount of "- n! H; A( w" j' b% t" k$ f
                       "road.  Either increase the amount of roads "
5 a( H* i2 }" |" {9 R# W                       "by increasing the GRID-SIZE-X or "
4 K1 ?+ c# Y0 c- f                       "GRID-SIZE-Y sliders, or decrease the "
5 s6 s" \) P) X5 M8 t1 V                       "number of cars by lowering the NUMBER slider.\n"
# X7 [8 e8 M0 w2 R6 }                       "The setup has stopped.")
$ X* A( J8 p9 u0 r% \- ?" d% X    stop
7 y5 Z( N/ o: b( ]4 A' V  S  ]
+ A. v2 s1 k. ~2 v3 W0 e! }# l: R  \. U$ a5 m4 L/ K1 I
  ;; Now create the turtles and have each created turtle call the functions setup-cars and set-car-color; j0 l7 w# P" X2 z7 M
  crt num-cars2 r, C/ d) |. s0 h0 b: U& b
  [& O; t& N8 d7 _. K: G6 g- U1 A
    setup-cars
1 f( S" G5 k7 i( {    set-car-color
2 J+ f% p- G2 ^" M' [    record-data: [$ i3 e% u' c) r9 T  A( h
  ]
" N# d8 \- p* b  @8 ^% i  @6 S2 ]+ h% }7 k
  ;; give the turtles an initial speed
7 `0 y. ^! e* M4 _; I4 N) P+ Y  ask turtles [ set-car-speed ]
8 R# v6 H/ Y% B+ W* n
9 i& n' r9 y/ p. c7 P  reset-ticks
- J! m( D6 J# ?& j2 Dend
: M* H/ P! o+ Z$ p" o1 y4 Z* |* p- A
;; Initialize the global variables to appropriate values4 f5 R4 a9 n. Q
to setup-globals6 g# k; E: A$ g
  set current-light nobody ;; just for now, since there are no lights yet
. g0 K6 u- Z8 n/ U: G: J; N  set phase 0& I8 z2 P5 x8 d
  set num-cars-stopped 0
7 F5 r  q; s; H: H0 f$ O  set grid-x-inc world-width / grid-size-x
% F6 v! I3 I1 Z/ V  set grid-y-inc world-height / grid-size-y
- R1 [. n: F% S) ^1 Z* b. s! t# f( U' A& ^
  ;; don't make acceleration 0.1 since we could get a rounding error and end up on a patch boundary
1 S* B! _6 r- d$ s  set acceleration 0.0997 j$ o/ w4 {' |" c  z: ?
end/ P) @5 Q0 @+ ~9 u2 a

; x& Q  K. u# P( P( \0 C;; Make the patches have appropriate colors, set up the roads and intersections agentsets,
, p* \2 V/ _% |' D;; and initialize the traffic lights to one setting# B& |0 \1 R0 y1 Y+ u
to setup-patches, p6 g' [- ?# S  {
  ;; initialize the patch-owned variables and color the patches to a base-color# b/ U# Z+ }2 o! f( z# M
  ask patches: u; H+ z& _" r. u. y: ]& C
  [
0 ~, U% S# C" T6 ]0 W& ]% c; o9 a    set intersection? false
5 @) M) q0 N8 X3 m( q    set auto? false: a0 M( n$ {  z3 f
    set green-light-up? true' T# G% c* m9 w9 k! X9 D! s3 s7 l
    set my-row -1
( W9 e5 v' S* C: c1 E9 b& A    set my-column -18 x) t- E( r9 O- @( d7 T( U, Y! b
    set my-phase -19 C" d  U! I  C0 H
    set pcolor brown + 3# k* e8 Y/ `) B7 h5 d" F* {4 ]# w
  ]: q4 ]/ a  q5 I; d) N( Z& B5 `
3 M; Y1 i3 Q8 V" I- F; Z$ z4 A
  ;; initialize the global variables that hold patch agentsets
4 Z& E+ R$ L5 k! H  a  set roads patches with
3 K9 ]+ |2 J. J8 G8 E    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) or
% e6 Q' X$ L9 H) Q) E# P# D    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]
% G4 r2 t* Z# Z- [9 p  W& X$ e  set intersections roads with
. A+ @9 z0 N0 h* X& `' ^    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) and2 y" x5 x5 y: [+ d
    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]
! i. g0 C6 b: W
  {& l5 y9 _2 P' g  ask roads [ set pcolor white ]9 q0 W; l& g9 _! d
    setup-intersections
4 d" ~% d! `( U8 V6 H3 Eend/ K- D3 N- R) J% j" k. Q8 L1 u
其中定义道路的句子,如下所示,是什么意思啊?
3 ~0 P. D; X' J! z$ O set roads patches with
) e. ?& o: K0 R( c9 A; f& N" j    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) or5 @7 Y5 x5 A& U/ \2 n- j1 J+ ~7 X& H
    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]# Z. T. @! J- F* q# P- T
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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