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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。
$ Z% A( {+ L4 P3 ~+ f" Znetlogo自带的social science--traffic grid这一例子当中,+ v8 f& Y* D' Q& M4 w# ]+ w5 ^
globals
& P' f: X. Q/ t! N6 E9 }: b1 O[
, W! L4 K1 S& K; U' S6 C  grid-x-inc               ;; the amount of patches in between two roads in the x direction+ K/ k) T& {7 O$ {- b2 _' v
  grid-y-inc               ;; the amount of patches in between two roads in the y direction( Z6 V) ~6 j" G9 _" N3 t
  acceleration             ;; the constant that controls how much a car speeds up or slows down by if
; L+ V: c8 h) U- t; s9 ~4 P  e; h( O                           ;; it is to accelerate or decelerate
, h# `. _, e, @( C2 E" O) W- I  phase                    ;; keeps track of the phase
7 e4 P* P" Q* @8 d  k+ `: @& X  num-cars-stopped         ;; the number of cars that are stopped during a single pass thru the go procedure
3 B9 r) O7 d1 b% u/ a6 l7 h  current-light            ;; the currently selected light! `* p* e8 F2 b# B

5 {8 \2 U! `9 E" x& I  ;; patch agentsets! _+ }8 {  C  M, h" l
  intersections ;; agentset containing the patches that are intersections7 o9 p' k9 o; T" T  J0 B( G9 r
  roads         ;; agentset containing the patches that are roads2 ?) q2 U- P, ?1 D" @* I) v) U
]* x) T2 b5 N5 l" R9 x9 F  Q+ K3 V

; ~, p, Q" O: @turtles-own
  H  k: U5 n4 ][# u9 ~9 H- U3 M* j
  speed     ;; the speed of the turtle
3 h7 V) U6 F0 Q- f1 `* @+ ~  up-car?   ;; true if the turtle moves downwards and false if it moves to the right7 v* k0 |6 z+ {$ u6 p3 e. v+ L/ L5 _
  wait-time ;; the amount of time since the last time a turtle has moved9 Q$ q) V& \! v' Z6 e
]
) u& B0 m% `% O! W# l( y$ {, B2 O4 Z% X) ^) \
patches-own
! s/ a+ g, ~7 p5 i0 `[
2 k1 r* h$ o+ i/ H  intersection?   ;; true if the patch is at the intersection of two roads
' `' c8 z( ~7 L1 q; Y  green-light-up? ;; true if the green light is above the intersection.  otherwise, false.
, l: D3 R  t; k; T6 r6 o                  ;; false for a non-intersection patches.% U+ J) ]8 j  x! _1 ]7 v1 J6 [6 x
  my-row          ;; the row of the intersection counting from the upper left corner of the: k- H  s/ r" M, n6 N. ?/ l  ^5 q6 f
                  ;; world.  -1 for non-intersection patches.
% ^% a1 [' Z/ k  my-column       ;; the column of the intersection counting from the upper left corner of the
. [* I! K# K! g- m8 o! }! ~                  ;; world.  -1 for non-intersection patches.- [8 Q0 V/ i+ u6 w
  my-phase        ;; the phase for the intersection.  -1 for non-intersection patches.
- z0 B9 _6 m, R1 X  auto?           ;; whether or not this intersection will switch automatically.
/ q& p- j1 b; f$ f                  ;; false for non-intersection patches.# ]1 ?: e8 E. Q
]
' I: ?5 a) ~7 Z+ e! H
. R! v2 d, P5 i3 z. ~5 R! A+ m1 H. G8 e, ^! B
;;;;;;;;;;;;;;;;;;;;;;
$ l, d- C% B: |# H' I$ Y9 F;; Setup Procedures ;;! @) H2 H) D4 D( w* h) h
;;;;;;;;;;;;;;;;;;;;;;3 B% ?9 v( Y. \" r; h" g/ {
  J9 M8 k- h) J
;; Initialize the display by giving the global and patch variables initial values.
) {! s% S# i$ l8 x7 x+ ?  ~;; Create num-cars of turtles if there are enough road patches for one turtle to* v. R4 W$ W* q( |
;; be created per road patch. Set up the plots.( g/ k. B0 S# O$ z
to setup
. K% u, _- K1 H* ?  ca  l5 l$ N# b: I2 R
  setup-globals
& v; \2 h* y$ E' O' @: U% s( F( D0 t8 {. _; u/ `3 e
  ;; First we ask the patches to draw themselves and set up a few variables3 [0 l3 H4 g/ u5 U
  setup-patches
, Y: Z  R# f  O7 {% _6 I  make-current one-of intersections" \( V- U& l+ O9 P; F! s
  label-current
! U- D7 K2 Z$ J5 q0 D7 f
6 ?: E! c8 c6 D  V/ g, r+ F  set-default-shape turtles "car"* F: P: T: Z3 @& h

7 n2 u) D  K7 o; P* @" ]  if (num-cars > count roads)
! k$ q6 M. w2 B7 b0 K, i  [0 I: z, @' d! z, p4 [
    user-message (word "There are too many cars for the amount of "
: S& V3 C- T! m! y) n                       "road.  Either increase the amount of roads ". k+ \/ @9 ~$ }8 L' q9 u/ @& @
                       "by increasing the GRID-SIZE-X or "0 Z& f6 E) m* ?+ y' K
                       "GRID-SIZE-Y sliders, or decrease the "# H% K* X) G( w7 M/ M" k! R2 B
                       "number of cars by lowering the NUMBER slider.\n"
- p$ Y) ?+ Z6 ], v                       "The setup has stopped.")
  v7 f4 X2 d; S+ q    stop3 j4 ?- C& f) \" ~/ a8 I' k# ~5 W; z
  ]  i9 B8 j4 Q# Q! Q- I$ n7 Z( Y; ^

/ W4 q/ |) L& @( w5 ]' s, N6 H2 R  ;; Now create the turtles and have each created turtle call the functions setup-cars and set-car-color; {9 u* \* @6 r' Y2 W) u
  crt num-cars
6 c5 e8 ~6 h; e* o5 m/ ]* c  [
  _. y6 A! G0 u. o    setup-cars/ J! x9 F  b. k
    set-car-color
! b6 v% i/ i/ |4 v    record-data; h4 K" L7 ?7 J. C- e6 c& c) D
  ]( W0 B! f# v" P4 p: X9 ~

4 R) R& N& R+ I' i/ G/ L  ;; give the turtles an initial speed1 q& ^! i! h. P& H5 S8 v
  ask turtles [ set-car-speed ]
+ z9 l9 Z) K7 [' Y3 G/ ?' _' q9 e* j2 b' o8 Y( |
  reset-ticks8 ]6 g9 R+ T& I
end
- |* Y9 M# _& ]; r$ W. v9 E! I& k& X$ o9 l/ |" a
;; Initialize the global variables to appropriate values0 G6 V6 N; t! ~% Z3 g. U. }
to setup-globals
$ Z& W: ^+ f" p0 K7 V  set current-light nobody ;; just for now, since there are no lights yet
+ z. A0 B4 G% M( \: G; Z# a  set phase 0
& x; T) x3 \5 Q  set num-cars-stopped 0" ]  w: _7 x4 T9 ~: F2 {
  set grid-x-inc world-width / grid-size-x. b7 B7 Q1 S4 @
  set grid-y-inc world-height / grid-size-y
, }0 v6 `3 i4 J, A4 f
. G- k" S* x& M9 b6 k9 T! ?  ;; don't make acceleration 0.1 since we could get a rounding error and end up on a patch boundary
+ I0 V, d7 z! B0 [  set acceleration 0.099
/ J/ h8 U( u. Z3 V, j: S. {7 lend" u5 Q0 i$ o& R- x

# g$ [2 i) B2 s0 m4 j1 m3 B4 M;; Make the patches have appropriate colors, set up the roads and intersections agentsets,
% V- y; w" L2 Y;; and initialize the traffic lights to one setting
% K" x3 O+ T4 m- h/ ^7 @to setup-patches
* |; |( n  Y! V0 S. E$ v  ;; initialize the patch-owned variables and color the patches to a base-color9 H( i2 C7 N4 N, x3 O$ X7 P" d
  ask patches, F+ |! z  t4 k% E, y$ r
  [
9 P: P! s- J# G& c9 `0 Z    set intersection? false, _0 C. Z6 ], d; f; e% i
    set auto? false
4 C! d3 |' b" g6 e8 {8 y    set green-light-up? true. i: g3 ~- g5 ?- X0 O7 J* K
    set my-row -1
3 K6 J' n) F9 C& C, Q    set my-column -1
! y8 Y# |& q, L: G( }    set my-phase -15 q; e* N, D) Q. j2 t# @4 T7 A
    set pcolor brown + 30 d5 S% T0 ?, F8 @5 x$ l4 F
  ]
* |9 s( h8 @' H6 y$ n- q5 w$ P$ ]* I8 `, U. k; X6 O
  ;; initialize the global variables that hold patch agentsets0 Q6 v. z+ p% }! Y& a( F
  set roads patches with
! c$ \9 p0 x# c( O+ ~    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) or0 H- ?& ^* @7 x: E& Q5 ^4 l: x3 g
    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]
% Y; I+ g3 _- G$ L/ @& Q: X  set intersections roads with
! i8 A) L0 W( l# Y6 b% ?    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) and$ v! d2 {7 V. F4 K, K3 D* O7 v
    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]2 [1 u' ^/ n1 p3 W7 W

- I( T6 q' ^3 A: H  ask roads [ set pcolor white ]
" @2 o1 q. ]5 K    setup-intersections
8 p  O. n$ @& [# s) D* aend
# `' _+ H) w; m其中定义道路的句子,如下所示,是什么意思啊?
$ W( R/ a3 X) a4 ?# w8 Y" X" \ set roads patches with
7 _2 Y; V8 M5 f, [/ K2 c# X9 q) F    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) or" s3 D5 l; H2 |! t+ r! H5 I+ G3 r
    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]2 s) \' ^3 L) K3 u9 H8 i
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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