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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。1 V0 z( S* k; b2 v% ~
netlogo自带的social science--traffic grid这一例子当中,( _8 h+ j5 t5 d; r
globals  E" I6 c% ^; U
[
% `* g( q( E+ K0 z% Z- y) B  grid-x-inc               ;; the amount of patches in between two roads in the x direction
, ?+ {% K& s1 T0 n1 i  grid-y-inc               ;; the amount of patches in between two roads in the y direction
% u5 a3 G; U% ?$ S- L1 F. l  acceleration             ;; the constant that controls how much a car speeds up or slows down by if
( P7 ]8 |) M% U% ^, {7 R                           ;; it is to accelerate or decelerate3 z* u7 L1 g* B
  phase                    ;; keeps track of the phase
" g  D0 a3 g; F; P* j% K  num-cars-stopped         ;; the number of cars that are stopped during a single pass thru the go procedure
5 c3 I! c) |& t$ k2 k0 o  current-light            ;; the currently selected light' c2 s* L- @) P3 s+ }6 @, u5 _
# c) x: j" l* u0 E6 m$ V
  ;; patch agentsets( @( G; w7 r4 J& g( E0 I  c
  intersections ;; agentset containing the patches that are intersections
0 _9 {1 X/ ~: S; u1 R: B  roads         ;; agentset containing the patches that are roads4 b) w- H/ f# N" B/ [
]8 x3 }- p% E' J  [: B/ {0 {* U+ S
, u  @% R8 S0 {$ R& h- n
turtles-own; H1 s" ~2 f5 ~! {4 i
[3 P8 U6 W+ [: w& O
  speed     ;; the speed of the turtle/ l/ o: r; Z: V
  up-car?   ;; true if the turtle moves downwards and false if it moves to the right  [! n: N2 v" N- i6 w5 [- Q
  wait-time ;; the amount of time since the last time a turtle has moved
3 }6 D8 ?, r4 T. d1 v! y]
: u! B# L' j3 D! f, L7 r4 M" N% c& u# I  I- Q6 f0 e+ W
patches-own& {6 A5 V3 b% A5 H# ?) P
[
+ y# ~  y1 @* w  intersection?   ;; true if the patch is at the intersection of two roads
. ^9 R7 [5 V0 ?8 A5 U  green-light-up? ;; true if the green light is above the intersection.  otherwise, false.% ?+ z# e( u. D6 R
                  ;; false for a non-intersection patches.
! b$ o  ]9 R, w* K% @; q  my-row          ;; the row of the intersection counting from the upper left corner of the. \4 c; Y6 V$ j. \
                  ;; world.  -1 for non-intersection patches.  I, ]  h" P9 T* a+ {% b: v* `" t( N9 I
  my-column       ;; the column of the intersection counting from the upper left corner of the
% t0 L9 H2 N5 ~                  ;; world.  -1 for non-intersection patches.2 ~( m$ F7 ?) Y" f6 ?# h: K$ W
  my-phase        ;; the phase for the intersection.  -1 for non-intersection patches.- d: X% z! G4 r" |0 L2 k. |' [2 w* o
  auto?           ;; whether or not this intersection will switch automatically.
  u0 L7 V3 W& h0 f                  ;; false for non-intersection patches., Q6 _2 t3 P3 x+ X. M( w
]
: S; G! S+ K- \; h+ ?" x  h0 I, G! I; d0 k% K' U
: X0 M% ?( I. z( \0 _
;;;;;;;;;;;;;;;;;;;;;;
; b! s- }- D4 ?. K+ ~;; Setup Procedures ;;
0 p+ Z  e# q8 p0 J6 c;;;;;;;;;;;;;;;;;;;;;;
  Y( t/ o# g8 l% ^9 g$ l
% f: p! Z- Q: l4 g' ]9 M: \$ };; Initialize the display by giving the global and patch variables initial values.
1 U/ v) j; a# g, Z3 r, f;; Create num-cars of turtles if there are enough road patches for one turtle to$ m5 m) A  M1 _* J/ u
;; be created per road patch. Set up the plots.& n/ ^: b1 b8 D/ H+ U: y# h; M. l1 i
to setup5 Y0 i/ Z( [2 n+ r
  ca9 k: G8 `6 q" e5 D! r' D0 a  a# [
  setup-globals* K- O" a$ g/ v2 U: c
2 T. _* t6 g7 S' v5 O/ h8 `$ @, ^
  ;; First we ask the patches to draw themselves and set up a few variables5 a6 g4 r4 P& A7 g& {/ G3 L, s8 q% I8 D
  setup-patches
; X+ q$ [2 R2 ~# [: k# e) C  make-current one-of intersections2 U, G$ O; n9 ]+ \- q. y' G
  label-current8 O3 [# k6 U, v4 R0 P

' q  E7 j9 ~7 T( Q2 @- e+ P  set-default-shape turtles "car"/ f! w* ?  o5 b
4 u2 i  A! P# H6 p3 z
  if (num-cars > count roads)$ y  @/ U: Z% w9 u2 X6 N
  [) ]0 A$ W! y( F! M8 ^/ r1 S
    user-message (word "There are too many cars for the amount of "
/ P; h8 Z4 U! A$ d, d: e2 v                       "road.  Either increase the amount of roads "  p1 I/ h1 R, E& ?
                       "by increasing the GRID-SIZE-X or "5 P. X5 H- V- Z$ h8 `* M  s
                       "GRID-SIZE-Y sliders, or decrease the "
8 d  J  N* c# z' y3 m" J2 x                       "number of cars by lowering the NUMBER slider.\n"/ [! Z, t" e1 D! \$ N( n& H
                       "The setup has stopped.")& V4 F& O" A) T' t1 K' u: m
    stop, d9 w* e. O% E- N
  ]
! d/ z' z5 P2 K" S
% Z* J! d) e4 r  ;; Now create the turtles and have each created turtle call the functions setup-cars and set-car-color
# l; f4 O4 E  H( v/ a3 ]  crt num-cars- @1 _! p1 n: Z& r
  [
6 w) M0 P1 i! p- b* w    setup-cars3 r% o7 {. b. [: O$ J( Y, O
    set-car-color
2 @) R, P% |: ~) h6 `    record-data
, N  F) y4 h9 G5 }+ e# J  ]9 S/ M! t7 j) k" U

1 e- ~2 P3 `) h* `" [  ;; give the turtles an initial speed
7 N- u7 L9 {: ]  R: X8 m) y8 V' O' |  ask turtles [ set-car-speed ]
1 X# C- h  }5 g1 N9 v
7 I  C7 V' V2 o4 L% ]  reset-ticks$ I# O( u% @# Z
end
6 r% K1 P& ^5 m) i- M
% ?( R* ^; g' ?7 d8 c5 X;; Initialize the global variables to appropriate values- j# r$ ]. g; U( G+ e# b4 F
to setup-globals! q( G% q2 E3 G+ F. @& L+ K5 V
  set current-light nobody ;; just for now, since there are no lights yet
$ }. z2 Q8 Y) N  set phase 0; S$ s" u" a6 k7 L  ]; v
  set num-cars-stopped 0
& X. t5 |' z/ F4 r! b; C  set grid-x-inc world-width / grid-size-x
9 `; @, W. b' K  set grid-y-inc world-height / grid-size-y. t5 v. m+ l2 U/ P/ e& Y
; t& o9 V  \5 u8 j& E
  ;; don't make acceleration 0.1 since we could get a rounding error and end up on a patch boundary  x8 [: ~+ c8 f# u% n  ^
  set acceleration 0.099
6 Y! q  \+ C/ f2 U  U1 Q. K& d- I/ K, hend- @, N+ f2 \; W7 ^' X& O+ ?3 L# [' N, ]

, Z$ h9 d$ j$ I7 {3 k;; Make the patches have appropriate colors, set up the roads and intersections agentsets,, k9 R7 c% ~% R* r: I. A; Q: h
;; and initialize the traffic lights to one setting
! O' }, [! I* Y' x9 q# ?9 Y& m( rto setup-patches1 n- ?& r# j1 I
  ;; initialize the patch-owned variables and color the patches to a base-color6 Q" M4 U& N' T
  ask patches& j  {1 G7 ~* R5 ?' R: m. K$ S. p
  [8 n" z! C; F7 i: L' S6 r
    set intersection? false
% A# [$ S& e) d3 \) A+ F    set auto? false
; m* ~) V. g. O0 \# n; F4 [/ X- ^1 F3 h    set green-light-up? true1 @* g; P1 u5 f& R
    set my-row -1
5 e- U: }2 W8 W6 Q6 l, p    set my-column -1
6 l7 X/ E0 Z2 E+ J    set my-phase -13 u# x7 P3 Z. Z4 ~& h
    set pcolor brown + 3: x! U4 ]2 E7 ]: S9 r; H9 ]7 l
  ]* j4 ], d; d4 F

2 P  d; J+ k2 e$ y! M+ t  ;; initialize the global variables that hold patch agentsets
( H; ?, S7 a# b; N; [; a  set roads patches with
+ U" p2 A! ]: b1 b! V; t    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) or3 q4 C4 `2 B1 q' e% C1 ~) x
    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]
/ W  R/ C4 X* n8 F$ X6 M  set intersections roads with5 O+ k5 E  c7 Q- f5 Q6 [8 m
    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) and0 ^$ x+ p5 [; L3 p) j! O" v
    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]
( L6 J9 E; }7 U! ~  c% z* [7 `. W+ @) n& V  d2 z* O1 P$ h
  ask roads [ set pcolor white ]
( J3 `" s; Z8 H& \    setup-intersections
3 {4 [: {9 ?" ]  ]% L8 hend
3 r9 j( Z& q0 y5 F5 A8 A9 Y' ^其中定义道路的句子,如下所示,是什么意思啊?
7 t# c/ j5 E1 y+ t& {, G set roads patches with
2 C: ]0 Q/ @  O2 x, w: f1 r    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) or4 S7 F/ {+ M% y. s7 r. \6 E
    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]7 k. M2 W& {: O5 T0 }& m2 ]
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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