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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。* M; \% u( W) a6 X
netlogo自带的social science--traffic grid这一例子当中,! E9 U$ Y+ \8 y$ i" \; t
globals  J; H* H# ~' `- i. x0 o' M
[6 f! X) X7 U( ]+ _! w* m
  grid-x-inc               ;; the amount of patches in between two roads in the x direction- b0 J; i( n6 z0 @0 X
  grid-y-inc               ;; the amount of patches in between two roads in the y direction
# F; [9 L. G8 v! J2 Q* ^  [2 ]( S  acceleration             ;; the constant that controls how much a car speeds up or slows down by if
/ f6 o3 J' t2 E3 ]/ }% z$ @# e                           ;; it is to accelerate or decelerate
( N' O. h( U* o) u$ _  phase                    ;; keeps track of the phase% s9 X  i  q7 l6 z, H" L
  num-cars-stopped         ;; the number of cars that are stopped during a single pass thru the go procedure
5 u! ~2 o- ^: V8 \  current-light            ;; the currently selected light2 @, Y. f3 y3 L7 }9 O) r
" ]) t" U" x) \, P4 I
  ;; patch agentsets
+ C/ Y7 l* i4 G7 X$ y4 v  intersections ;; agentset containing the patches that are intersections
$ I9 o% \+ {$ Q/ g  roads         ;; agentset containing the patches that are roads
( J$ T8 ^2 T' @, X' z6 S]
  W- P  O& ?) }, R/ c$ t2 J8 Q4 a' A. G' _. v4 {" X1 [; @7 a
turtles-own8 A/ W/ Q0 ^: _8 K; o" F; R# B
[+ H/ ~7 P" T+ g; E% [
  speed     ;; the speed of the turtle: B/ `& h$ k! F, X6 D" w; }! v0 N  ^
  up-car?   ;; true if the turtle moves downwards and false if it moves to the right
$ t, X- m5 f& Z. d* ]  wait-time ;; the amount of time since the last time a turtle has moved
, [  ^4 L+ I. Q3 [% u/ v+ A4 F]+ H0 `* S. l- J, q8 s7 e$ }

$ u, @4 V# O/ h' a+ w* j: a7 Apatches-own6 b) z; y: p3 g5 w& m2 [
[5 a9 h) G2 H9 j/ q% Z# {0 r
  intersection?   ;; true if the patch is at the intersection of two roads. q- p+ H" K2 I! a; ~, K6 V7 J0 I
  green-light-up? ;; true if the green light is above the intersection.  otherwise, false.
9 n+ @4 k" J0 i" s                  ;; false for a non-intersection patches.
* D2 O' W( n1 J7 S2 N. l# o, _  my-row          ;; the row of the intersection counting from the upper left corner of the" R2 {0 ?) g: G/ j- ?, G1 x
                  ;; world.  -1 for non-intersection patches., ?  H5 a0 ]0 Z2 L4 D6 b
  my-column       ;; the column of the intersection counting from the upper left corner of the
- V$ |' a" G- m9 }  w                  ;; world.  -1 for non-intersection patches.
6 B4 r; _; N! g. ~& [  my-phase        ;; the phase for the intersection.  -1 for non-intersection patches.
0 Z) V" f9 K" z+ f6 w  auto?           ;; whether or not this intersection will switch automatically." t/ C9 w. H2 j1 K( X$ a8 l
                  ;; false for non-intersection patches.
1 ]/ i8 ~$ W# H) f( c$ y( R]" _. t8 V% _! Q: |
0 A8 u( h7 C" O/ s8 l$ W

* A( v8 D. ^5 [  z7 `& M9 S;;;;;;;;;;;;;;;;;;;;;;
; U* }1 P# K! l1 s;; Setup Procedures ;;
) v& n* S3 u. P  L/ M6 O;;;;;;;;;;;;;;;;;;;;;;
2 p+ V7 l) s4 w0 Z! L! P6 ~+ b8 Z- \4 K
;; Initialize the display by giving the global and patch variables initial values.
, f. u$ [6 ]/ B  m;; Create num-cars of turtles if there are enough road patches for one turtle to
* J! n' t5 V+ t8 |3 O4 G;; be created per road patch. Set up the plots.
  h# A+ ~8 ?5 U- z% j7 rto setup) }# u0 ?& Z' v; y& ]: a1 C/ Y( I
  ca
4 g# z5 I6 a, U/ u& G* U: j  setup-globals
8 b( Z, n( B1 `1 ~0 R0 q0 G  v) i# u3 J6 O1 Z
  ;; First we ask the patches to draw themselves and set up a few variables2 {/ }+ U% G3 a
  setup-patches, e8 s2 w# R0 A
  make-current one-of intersections
  z6 ^0 N! V2 {, f2 N8 V) I7 X% P9 _  label-current  z& F( T' g, b' ?
- {! q* p" v5 j' M! x( G. b  V
  set-default-shape turtles "car"
1 R- f- o4 R7 O9 {
+ a7 k7 @- ~0 H1 |; r, X: K  if (num-cars > count roads)' n# P8 s# X* z# v6 |- h8 G# u5 [- ?
  [; P: Z9 B: v3 k
    user-message (word "There are too many cars for the amount of "
; i$ Z, u7 b$ @. o0 X, V                       "road.  Either increase the amount of roads "
" J! {2 U$ Q$ k* k4 g7 A6 H) `                       "by increasing the GRID-SIZE-X or "
; r0 c. b. E: Y3 Z. c$ r- H                       "GRID-SIZE-Y sliders, or decrease the "
8 G2 k( b2 \. {+ s; F0 p7 g                       "number of cars by lowering the NUMBER slider.\n"
6 Y4 ^7 s- K/ Y# O0 z                       "The setup has stopped.")
7 w" ?9 T/ F7 ?    stop
# l0 j, e: y6 b! N  ]
$ @3 a. R' a/ q( q
! b9 `+ H" ^6 h  ;; Now create the turtles and have each created turtle call the functions setup-cars and set-car-color
- {% J4 c0 h3 B6 `% h! x) J  crt num-cars9 K/ z9 F% M" l) u0 s$ F2 n( P
  [) [% P/ z) q9 G7 Q7 x  x2 k" ~
    setup-cars
% J& y( J* ]5 W+ \" \    set-car-color0 ?% ?/ J; A1 G+ U8 h
    record-data; Y" f" k9 D( e: C) _4 l
  ]
4 k5 c/ V( B( l: [4 u7 a  e
. i# s3 h* R0 n( t& M  ;; give the turtles an initial speed) C) X- [3 Q; c. t' J
  ask turtles [ set-car-speed ]
! o" b  _# G/ S3 F( `" e$ t7 }3 p0 Z1 B# J
  reset-ticks
9 {5 Z$ D3 J6 ?) k& y# _8 }8 [end
% `8 D- A" ?1 {% {& A7 H, n6 H$ h# A- _: O
;; Initialize the global variables to appropriate values3 ~6 A% i4 M* i5 s. V/ W: T' q1 }
to setup-globals
/ N# Y  w# S3 |" W- P4 i1 ^  set current-light nobody ;; just for now, since there are no lights yet& U9 D0 Y8 [- J: o
  set phase 0
) z! u7 s0 ~+ G* [0 y& p! B  set num-cars-stopped 01 ?. |% J. _4 K6 I0 b' s* n  k
  set grid-x-inc world-width / grid-size-x
' I; S3 T3 p! W0 z1 h  set grid-y-inc world-height / grid-size-y
& B! m3 O" e" [5 O7 C
, P, P3 F* S. M# M3 Z" U  ;; don't make acceleration 0.1 since we could get a rounding error and end up on a patch boundary
& ?* t1 k; n+ M# W  set acceleration 0.099
% b' W/ g: l# {+ t" \) Iend
5 i+ P3 C% Y7 f1 A0 p! w1 r3 \4 r- T% o+ |2 w( }
;; Make the patches have appropriate colors, set up the roads and intersections agentsets,( e+ W) @  n+ y$ u- @
;; and initialize the traffic lights to one setting3 h5 A( a3 E7 @* C% W, x* X
to setup-patches
5 m0 f) ?7 m0 k! s' E" z  ;; initialize the patch-owned variables and color the patches to a base-color2 I! }9 m. h( ]0 i4 A7 z" e
  ask patches+ G. p* J0 t4 S" {9 e& z% o
  [) y# o1 s# |5 h
    set intersection? false' W5 K% y4 X% K
    set auto? false# c0 a3 [) s7 p6 i
    set green-light-up? true
/ v/ k: ?; P! h& g- M3 f    set my-row -10 @5 V- C8 |, i
    set my-column -15 V+ T* P; Y: y1 f$ i8 e
    set my-phase -1
0 W% P9 m2 ]0 U* n! I    set pcolor brown + 3) u. _, b% F2 ^0 Z* u
  ]
/ |8 {1 H2 F. o
7 k2 Y  t( r8 D- w  k  ;; initialize the global variables that hold patch agentsets& }1 c$ R9 o6 r1 P
  set roads patches with, ~" @$ Z6 P5 N: S. D- N
    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) or
4 O. X8 m  B* a# w: R    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]
# D+ e/ p. J5 A2 O5 M  set intersections roads with( r" S4 G8 {# j9 U* \
    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) and9 v3 _+ Q. T+ y6 }8 ~4 \/ H. v
    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]
8 A  ?0 d/ G5 w  E5 }$ v) N
' c6 j& l0 A6 l' t# g  ask roads [ set pcolor white ]
  }+ u' s" ]0 `! ~6 i    setup-intersections6 u' K: `* x+ Q4 l2 _
end2 B, @. g+ z5 A3 \3 P
其中定义道路的句子,如下所示,是什么意思啊?: _$ x" j  Z8 |8 l( {1 r8 D) W
set roads patches with
* w6 L2 {+ G9 l. `" z/ w    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) or
" l( f2 T6 s: V5 U" q    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]
  R6 E8 y+ Q) k6 t( K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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