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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。
$ f) b9 V8 T. F" V; }) Inetlogo自带的social science--traffic grid这一例子当中,
. R- a6 y: i& d& _+ Z* hglobals# i4 d! A3 S0 K+ K6 f" L& y( b
[
# f4 k/ a1 B7 W' A; H/ _  grid-x-inc               ;; the amount of patches in between two roads in the x direction$ A! k0 D4 k! R
  grid-y-inc               ;; the amount of patches in between two roads in the y direction
& Y4 g% C7 }/ D) H2 a  acceleration             ;; the constant that controls how much a car speeds up or slows down by if
2 k5 m3 J1 {8 |6 T: ]: U, s/ n) h                           ;; it is to accelerate or decelerate
1 ?0 H) S$ W5 |3 x! p. `1 C  phase                    ;; keeps track of the phase
" z0 w9 K; H* g) o  num-cars-stopped         ;; the number of cars that are stopped during a single pass thru the go procedure
% k1 k, q  G$ @. r4 ^; L3 c; f) \  current-light            ;; the currently selected light5 l; u/ A3 @" \

) S+ G1 K7 Y4 [, Q/ r! B7 u  ;; patch agentsets2 c1 }- ?5 o' x6 R' P8 @
  intersections ;; agentset containing the patches that are intersections
+ b, \; R0 B8 u- O2 H) b  roads         ;; agentset containing the patches that are roads
- d; s$ u6 S% I( _0 @8 q+ d]
* L( d& ]5 H$ ~( b& R6 i8 |( ~! v) U! G& `% T
turtles-own4 x- G7 m: ?5 L  Y% @
[( a/ z" t  J: k+ r$ v* z$ t' z
  speed     ;; the speed of the turtle
/ g  u: T; R! W1 |( i$ K, N  up-car?   ;; true if the turtle moves downwards and false if it moves to the right
0 Y9 a# {" \. C$ \! r  wait-time ;; the amount of time since the last time a turtle has moved
( [4 {# Q8 N! F/ [. Z3 l]! }# P( M; c: g8 L) n1 ~
6 w0 f( C6 z' E2 f8 `5 i, J/ a
patches-own
4 s" Y$ |+ o. }7 o[
& N7 b6 r' V: @. l  intersection?   ;; true if the patch is at the intersection of two roads& L) B- r3 R8 V+ g2 c# d
  green-light-up? ;; true if the green light is above the intersection.  otherwise, false.0 H% k5 D$ t/ C) {
                  ;; false for a non-intersection patches.9 S1 S& Q2 y# U5 s* X* G
  my-row          ;; the row of the intersection counting from the upper left corner of the
: k8 w3 z/ U' ~$ `: \  n  X                  ;; world.  -1 for non-intersection patches.
! `' `2 e# K9 q7 t  my-column       ;; the column of the intersection counting from the upper left corner of the: @( M1 B' q: O$ Z2 Z- Y
                  ;; world.  -1 for non-intersection patches.- Z2 r  R" G* q. v% e! Z6 _
  my-phase        ;; the phase for the intersection.  -1 for non-intersection patches.
# ^( O8 a. P+ T, X  auto?           ;; whether or not this intersection will switch automatically.  u; H* E& n% V# w( s' ?0 B2 e$ s
                  ;; false for non-intersection patches.8 K0 T- ~6 n' s7 [+ K
]
, p4 v% e- j+ w# j0 |. O% n$ b- I

  |: Q4 f* ~2 @2 t( B;;;;;;;;;;;;;;;;;;;;;;0 P( _# |: n- ^1 F! r2 U& M
;; Setup Procedures ;;
. L! f( h& l& L# N. Q;;;;;;;;;;;;;;;;;;;;;;  {* _3 i& _* }, A) t4 q% M. F

3 _5 _2 x7 A  S/ x. `% A. P' k;; Initialize the display by giving the global and patch variables initial values.
8 Z4 [4 C+ L; f2 S. A0 l;; Create num-cars of turtles if there are enough road patches for one turtle to3 s2 F- h# H2 l: _5 q  m. q
;; be created per road patch. Set up the plots.9 ]% y$ N) C0 A$ x$ Q
to setup
- T7 g9 P8 E2 U  ca) ^' f$ ^7 o4 i6 ^% X
  setup-globals5 J' v, ?3 v; Y+ M+ Q
- h  f' {9 U- r$ j4 o. T' u' V
  ;; First we ask the patches to draw themselves and set up a few variables, k) ]3 Y: u. N9 ~! D! O
  setup-patches: X! I" A3 l$ _; M+ j0 h
  make-current one-of intersections
3 l) w* ?8 R8 G2 X/ o  label-current" n8 N( d& g$ p' x( v

  M2 [: k0 j* H. Y# x7 E  set-default-shape turtles "car"0 \. S# f, y* c6 [9 N
: q- w) ^( d6 h/ s  Y/ e8 `: U/ d
  if (num-cars > count roads), |* B8 P' @% u4 e4 j# p
  [
+ L: |- y6 m' Q  d" }    user-message (word "There are too many cars for the amount of "
3 a: {$ C% c* U3 v$ \& ^                       "road.  Either increase the amount of roads "
% H7 I5 f# M# n1 H9 R) h4 v                       "by increasing the GRID-SIZE-X or "9 ~5 e9 a8 S; K
                       "GRID-SIZE-Y sliders, or decrease the "
& Y6 q4 z0 H4 T' A                       "number of cars by lowering the NUMBER slider.\n"
0 z6 Y7 ?8 {$ k4 Z5 Q: e" B6 I2 [( b                       "The setup has stopped.")
- E7 [$ U. \, a: t: t/ ^    stop1 D% q# c9 \* E" c! m8 J* O
  ]$ `8 E0 N9 `4 T9 m: ~

4 G6 x5 S* ^7 W: H& s  ;; Now create the turtles and have each created turtle call the functions setup-cars and set-car-color+ Z0 |+ x+ \# l! I2 q  u2 D
  crt num-cars1 h, O% N2 K; l3 T, ]6 ^/ ~
  [  q9 o# V$ }% V3 S! Z( L
    setup-cars9 w5 ?4 M5 K' W7 p* [
    set-car-color
7 z2 D4 w0 q. P- u( a& S  d    record-data
7 U5 z, ~& Z! L+ {( H4 E9 N  ]
7 J+ h7 u( |- b, z! H
- b6 F+ ]5 W! j6 g3 I0 U  ;; give the turtles an initial speed
8 L# @7 H3 b* e4 H, _  ask turtles [ set-car-speed ]
& c5 |  ]$ i4 O# d, t
2 d3 @, _/ ^) z) G) U. n- }  reset-ticks6 E( j( I% G% ~' T0 T! U. ^3 E
end$ H# u# Y, E# C7 Q+ Q
/ ]* Y) }  O8 p8 }$ I9 i) j
;; Initialize the global variables to appropriate values0 Z( e2 j" @, j: v$ J& a4 d- }
to setup-globals- I) U" h3 f4 D+ h  ~  |% i. B7 |
  set current-light nobody ;; just for now, since there are no lights yet% u" c9 y7 V. P1 @3 |' F
  set phase 0
. y$ o" {2 u2 V5 j  set num-cars-stopped 0) \7 F7 i  _2 F& J8 v2 g$ m+ [
  set grid-x-inc world-width / grid-size-x
; `5 M: c0 s, t- Z1 W& c  set grid-y-inc world-height / grid-size-y
4 u3 z6 n- l& _& w6 J+ r# Q! D* |: y. Q6 w
  ;; don't make acceleration 0.1 since we could get a rounding error and end up on a patch boundary5 o8 @6 }; h( g$ ?5 e& L0 p
  set acceleration 0.0993 o1 s; E7 S1 v* T, H( h% @! b
end
; A3 E% M1 l( L0 U8 {* W2 c4 u- X8 B1 q
;; Make the patches have appropriate colors, set up the roads and intersections agentsets,& s0 [- V) s7 G
;; and initialize the traffic lights to one setting
$ x2 l  {5 X: q4 L/ w8 e$ lto setup-patches
$ l8 G* n. G* n9 Q* T  ;; initialize the patch-owned variables and color the patches to a base-color; @* D; R9 l( c
  ask patches, k) ]  R3 u# u& X# @' F) M, C+ L* c$ _
  [
6 s( f0 k8 _9 G; y4 S$ d    set intersection? false
; ?9 D. p4 a2 y! I# x2 s% F    set auto? false
8 `0 a, r# i) `6 r, K    set green-light-up? true
; f4 n9 O+ ?: V0 t) S+ {/ p' j) M    set my-row -1
6 w# [4 j) [' C: T- g4 b  j    set my-column -1& r3 V, G2 z* U* p, D" W  t8 ^8 M0 s
    set my-phase -1$ J6 r5 |7 C3 z0 r2 L& Z* h5 }
    set pcolor brown + 3
1 o7 ]' m" W9 W! a, B  ]* ]3 ^& D; s  b* S* T) [

0 S5 @% k# u; z/ v  ;; initialize the global variables that hold patch agentsets" a9 O* q8 k( d
  set roads patches with
6 i. B+ f$ Q/ {& R, P3 T$ ?3 I    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) or+ v, X/ A- S8 K4 t' J
    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]
' z: [* a, e9 J3 Z* i  set intersections roads with
2 R" [( O" u/ n$ y3 `1 ~' P    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) and
# d3 c: m4 p0 M' ]! v    (floor((pycor + max-pycor) mod grid-y-inc) = 0)], q$ A& d# l* h6 Q! M

+ c8 U1 U4 X$ E+ E$ \% V  ask roads [ set pcolor white ]
& [/ d1 j: e* F: ^5 W4 s( D; q    setup-intersections
* y0 ~0 W$ M  V! vend3 a# U; I) o- [" B9 n5 J5 z
其中定义道路的句子,如下所示,是什么意思啊?! U# E1 z! M0 X4 G
set roads patches with
, Y" b( M) x# S) X$ ]$ v    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) or
$ m9 g( W: Q9 B8 ]; W    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]
) O, S. Q( A$ m  B0 J- r  ?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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