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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。
# u0 L" o0 m9 |1 T7 s! a& Enetlogo自带的social science--traffic grid这一例子当中,6 {0 F) X$ }- U3 @
globals- R4 _% ?( i  p8 _' b
[6 H$ _4 _+ i! i5 q( R
  grid-x-inc               ;; the amount of patches in between two roads in the x direction" |4 k# \) s& c0 \5 V( O( m. P  `' O
  grid-y-inc               ;; the amount of patches in between two roads in the y direction$ a# z) T3 R4 x$ a! T
  acceleration             ;; the constant that controls how much a car speeds up or slows down by if( q" p# M6 g# c. I: |2 S9 M# z
                           ;; it is to accelerate or decelerate
1 a4 c7 s1 F& g3 F% ^  phase                    ;; keeps track of the phase
3 C$ K3 o& L0 \7 n' R% }9 V  num-cars-stopped         ;; the number of cars that are stopped during a single pass thru the go procedure
; o4 N! a$ B+ h3 B; k1 r4 y  current-light            ;; the currently selected light
" B# N# P; @2 b" }( Z- e# Z! l3 U  I2 d: v
  ;; patch agentsets: ]) d( ?) R% q. y- ^
  intersections ;; agentset containing the patches that are intersections. q& w# p5 ]2 D' ~( p4 ?& n6 [
  roads         ;; agentset containing the patches that are roads
/ e+ y. b1 B' V8 x/ x]/ _8 }  }! g/ n, C% n
6 b5 t  Q: w' ]6 x" G
turtles-own
6 Q, q% H2 \$ ^[
4 p7 c" h/ d. ^; t( d3 K9 `+ l  speed     ;; the speed of the turtle7 G6 f6 d$ Z0 d$ ~' z
  up-car?   ;; true if the turtle moves downwards and false if it moves to the right4 ~' c8 a* O+ B  r: r/ p
  wait-time ;; the amount of time since the last time a turtle has moved
' G+ W, c4 B9 U& S% r]+ i( f/ K# @% x
4 U6 w- T; C+ R# v; d8 g1 P
patches-own
2 \5 [4 S- j6 A& s3 X/ z2 t4 v: z[
. k& e, z7 C8 r& z) j5 P# [# Y  intersection?   ;; true if the patch is at the intersection of two roads
3 n: j4 r( ]1 ~2 \  green-light-up? ;; true if the green light is above the intersection.  otherwise, false.
7 t& X$ S7 z" {) S& X; e, y! Y' A" ~                  ;; false for a non-intersection patches.4 Q+ K( S4 \. B. e% `7 u+ N: c( `. t3 N
  my-row          ;; the row of the intersection counting from the upper left corner of the! L. m5 o% T, {3 G4 C; U5 l: C: i
                  ;; world.  -1 for non-intersection patches.
/ l8 A% J1 n" P. a  \6 T- Z1 O  my-column       ;; the column of the intersection counting from the upper left corner of the
5 z3 Q8 `. f0 b$ Y1 L+ w+ P                  ;; world.  -1 for non-intersection patches.
. ?3 ~7 h: n" \  my-phase        ;; the phase for the intersection.  -1 for non-intersection patches.9 |% _5 a& `+ |; n+ n6 }+ m
  auto?           ;; whether or not this intersection will switch automatically.
0 S/ E3 C; a" [                  ;; false for non-intersection patches.
$ A- T+ f" J( H0 D" h8 ?]
  `4 g: m% v( g' q( V3 R) F5 `: x- }% k2 ^. j

0 a1 X: H' r8 G+ p6 {' ^;;;;;;;;;;;;;;;;;;;;;;
. j* Q& p, f% d7 E;; Setup Procedures ;;1 e1 L8 @$ V" s# C
;;;;;;;;;;;;;;;;;;;;;;
) ^; a% R$ v, t
  o( I, ^2 u( l) A8 [! X% t;; Initialize the display by giving the global and patch variables initial values.
. D4 |& U2 U. N7 };; Create num-cars of turtles if there are enough road patches for one turtle to6 [  a) l1 p( O# j6 c, c9 [% K
;; be created per road patch. Set up the plots.
* v; x1 d, j; b( [% O; Uto setup
1 H  g, m4 Y# @! H5 l3 b1 ^  ca
1 U( {+ M) \, z4 [% d  setup-globals
+ M3 w. W4 }" b4 E  p6 R- ?( N: _0 J, Q3 r  v
  ;; First we ask the patches to draw themselves and set up a few variables
& |' d! P% B& r  L" }  setup-patches
9 M9 a" O4 P( r6 l+ M5 \  make-current one-of intersections
. z- J, g: V# Z7 n  label-current0 j! K& |" E  n* y3 c) v- ^
$ x5 v! n6 M7 v7 K. S7 M
  set-default-shape turtles "car"
- o7 Q+ H' l+ v: W  w
  c. ]! n( e- l: k+ H/ p3 v  if (num-cars > count roads)5 Y. A6 B, ^8 S" H+ o. K
  [8 d6 ~' _1 G7 c* C* v
    user-message (word "There are too many cars for the amount of "
) h" c; j2 D: F                       "road.  Either increase the amount of roads "1 r+ q6 E) g. a% A0 H- a
                       "by increasing the GRID-SIZE-X or "
6 }! M0 {3 }2 j# m+ d9 j0 J                       "GRID-SIZE-Y sliders, or decrease the "
  c* T; g: N; z4 G+ A# l                       "number of cars by lowering the NUMBER slider.\n"
  p6 e! ?3 a! a9 y, u: K  ]                       "The setup has stopped.")
# n* W" P* U( s- G) d$ Y5 K( t2 J    stop( V  ^! ]9 ^  o- j% R
  ]- t* w+ k- p; \, q
1 @5 i  C' P& D1 \! ]
  ;; Now create the turtles and have each created turtle call the functions setup-cars and set-car-color
7 h! P9 P& o0 V! `5 F* i+ [: x2 {  crt num-cars
3 T3 R6 {5 E$ w2 }  n' v2 ]2 r1 O  [
7 G' |  i% I) ~  v    setup-cars
1 c$ h  b: R" B2 Q    set-car-color
5 V# G  e9 B7 g- _- k9 M    record-data# X6 W# w4 t8 N5 N( P, D9 n. v
  ]5 _( e+ f+ ~. w" N" _7 S3 c% @
; Q- l1 S6 H9 r/ o( |, P0 X4 `4 u/ n
  ;; give the turtles an initial speed% X, _# [! }& s3 o1 g  z
  ask turtles [ set-car-speed ]
" Z* F5 |* H$ l1 ?- |2 {; X6 t
( t7 H/ @8 a8 T. P: S- G  reset-ticks- X2 y0 s& C4 }7 I! \
end" A- p; B( Z" ]; g; p! l( v

" Z6 g4 T  h+ W& C2 q" U1 ?;; Initialize the global variables to appropriate values# d1 M4 n* s- n
to setup-globals8 x7 E+ Y( V/ G/ W% d
  set current-light nobody ;; just for now, since there are no lights yet
8 q5 n! P) S# S3 [7 h8 Z/ U  set phase 0: Y3 ~; h0 Y, `9 l! {
  set num-cars-stopped 0
; A% R; T5 k4 c% q' |  set grid-x-inc world-width / grid-size-x
, p- S" [6 p$ o1 _  set grid-y-inc world-height / grid-size-y
; b) `$ T4 ?% n0 r& O* `4 Z* Z6 Q: R. F! M; G
  ;; don't make acceleration 0.1 since we could get a rounding error and end up on a patch boundary/ P0 l5 M* ?! X" a! ]2 M5 b6 h
  set acceleration 0.099
+ B. M, ^6 ?$ }, n7 m# p8 Vend
( j$ a! k5 N! T
( [# g) u: c5 X- W, ~9 {;; Make the patches have appropriate colors, set up the roads and intersections agentsets,/ |0 b( f: p  M% H6 b
;; and initialize the traffic lights to one setting
. B( H( n& e# P, y  S! X6 C% v* kto setup-patches
0 A" a2 u3 G" _  ;; initialize the patch-owned variables and color the patches to a base-color' Q8 d$ B" i6 W8 m5 M( e
  ask patches; V- c3 S5 P1 x, A3 ?; H5 v
  [! U" Z$ V% J& W
    set intersection? false
6 \" s8 B2 x* X% e" v" E. d0 X    set auto? false, S. f( b8 b/ V- e3 a
    set green-light-up? true; W. K1 b' q: v4 i6 G) @4 h- `3 i
    set my-row -1/ B8 g  I0 F0 s' U8 K( D
    set my-column -1
' J1 s4 [+ v5 A: P- H+ Y    set my-phase -1
. g+ n% A- m" x$ b0 a) M    set pcolor brown + 3' K7 y  y  d8 y8 I& X
  ]
' u  f  f! X: w
( ~6 i, F: N* ]  [3 |7 d+ {  ;; initialize the global variables that hold patch agentsets* N6 F5 Z- `& g" g/ g5 q1 t( P
  set roads patches with- t/ L) l3 }; M% q- s( ?. R
    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) or& M- |% C! F1 y0 K! |2 H
    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]. U% a/ i/ p" D% j/ r
  set intersections roads with
, U: t9 g# D& H9 R' F1 f    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) and
+ H5 e2 ]  B- P2 l+ V3 D. Z" `* H    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]/ S/ G; N* \5 k# R/ R: g8 B  C
6 H) D+ @4 R+ ^) u* o- s
  ask roads [ set pcolor white ]  o5 y/ ~) w( Z6 i! a
    setup-intersections
$ R8 M; x9 K: ~$ `end( w+ S3 N8 q7 Z
其中定义道路的句子,如下所示,是什么意思啊?: T6 t6 ~& ~$ F$ ]  W- m7 H6 u
set roads patches with
  y6 E* ]& h  W    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) or
5 j/ G4 [: X3 V9 T$ P( q# D' @    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]
0 `' r" t3 |9 c6 @/ b% e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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