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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。7 o3 O* J; ]) K7 I: z" f7 n5 G
netlogo自带的social science--traffic grid这一例子当中,
2 ]. b1 M- ?) F, I4 Mglobals% Q' X0 s6 e; j' R
[% O+ F1 Q7 P7 l- G
  grid-x-inc               ;; the amount of patches in between two roads in the x direction4 D3 ]. z; d: g+ n0 @9 Y8 B% P/ S- i* E
  grid-y-inc               ;; the amount of patches in between two roads in the y direction
0 {8 c/ w6 p6 w1 ^, Y  acceleration             ;; the constant that controls how much a car speeds up or slows down by if
7 k. y) p3 g/ M                           ;; it is to accelerate or decelerate/ I( U1 }6 m" i7 V
  phase                    ;; keeps track of the phase$ z2 g' N8 t- e: j6 U) ?
  num-cars-stopped         ;; the number of cars that are stopped during a single pass thru the go procedure# a2 j) f4 ?, G: x! z
  current-light            ;; the currently selected light
( j5 m7 q, D& O+ Y- h
4 c  ^/ O) L+ n* a5 I( f: N( j+ t  ;; patch agentsets
1 {9 i4 |' z3 B8 ?+ j) d$ X/ ]  intersections ;; agentset containing the patches that are intersections" _) c% q8 X; ~: w4 v) Z, g( r
  roads         ;; agentset containing the patches that are roads
: W; k4 f- r5 E# S  U$ j]7 j7 |- P, U. Y+ V- l

) \0 V1 p' _# N$ O. n4 |turtles-own
/ c4 h- h2 u# m* x$ w[2 W/ ~- b( y* J# A% _
  speed     ;; the speed of the turtle
9 o: r8 B! `" C4 [5 d5 J1 u  up-car?   ;; true if the turtle moves downwards and false if it moves to the right
1 \' q1 g1 F' Z& S  wait-time ;; the amount of time since the last time a turtle has moved
7 E' N) r; o; f]
' W3 l/ b+ @7 k% C/ J0 W
0 V% C2 q% i6 Y+ kpatches-own' l! U% O; ]) `! e! H) T3 P9 \" S, j1 U4 n
[
+ h7 f% [  J: U3 g  intersection?   ;; true if the patch is at the intersection of two roads
5 c$ I! X' j' Z  green-light-up? ;; true if the green light is above the intersection.  otherwise, false.
9 V( ]! J  V8 e# f. P0 g                  ;; false for a non-intersection patches.& x9 \2 ]. ^- ?& l
  my-row          ;; the row of the intersection counting from the upper left corner of the
" H9 G+ k: F0 D5 ^2 C! J                  ;; world.  -1 for non-intersection patches.3 F( L0 f: P! {% d! T
  my-column       ;; the column of the intersection counting from the upper left corner of the
# P2 [$ j/ m8 G7 ?. ~: S                  ;; world.  -1 for non-intersection patches.1 L( {! y% @) M# [. F$ H
  my-phase        ;; the phase for the intersection.  -1 for non-intersection patches.  [1 ^9 c" _& A' M% q6 x+ F6 o  n
  auto?           ;; whether or not this intersection will switch automatically.0 T2 `6 U/ _: G4 ^' R8 E
                  ;; false for non-intersection patches.
8 u. m  ~5 v  G9 ?: [+ z/ r]
2 Z7 y. p1 n- |/ J/ U4 s0 V* ^: _4 @1 Z# Z- `4 |: L# N+ H6 a

6 z$ J- H$ N! X8 {;;;;;;;;;;;;;;;;;;;;;;7 J3 @7 ?7 I# O( t
;; Setup Procedures ;;) y  E# t; ]4 D0 \: u
;;;;;;;;;;;;;;;;;;;;;;+ F+ z; ]! e3 }5 T4 H4 h8 O4 y

& g; G& V* j5 ?- m;; Initialize the display by giving the global and patch variables initial values.! T* e; Z  @: n# E  J
;; Create num-cars of turtles if there are enough road patches for one turtle to
, B' n% F0 i: v' j;; be created per road patch. Set up the plots.$ g, d' W" @5 o
to setup, n( k( j% j5 h* E" t
  ca3 }% F( [* x/ W
  setup-globals; g& T* \, h) X) U* C; _

0 P5 U$ {& `( w1 U. v  ;; First we ask the patches to draw themselves and set up a few variables. E, \# W0 a. h$ |1 L
  setup-patches
5 y- p  y& R( y) }; v6 Q4 `& _  make-current one-of intersections# ~/ t1 L5 P% i! f; @9 D* _2 J* |
  label-current8 w1 f' F- N% C0 x% P: U1 W
5 H$ R4 X2 o( R1 @# \
  set-default-shape turtles "car"
3 ?9 X$ m4 n, V( z# ^# u' w0 d* s5 o5 [+ V/ Z! {! K+ W4 C: [
  if (num-cars > count roads)
% i9 s1 T: s* J4 J0 m* i) e0 j5 [  [
' ]  F6 Q: q" E, N0 q    user-message (word "There are too many cars for the amount of "
  o+ E# {' H* q2 n  x" n2 [; O. V                       "road.  Either increase the amount of roads "
, X% p& i3 s  o1 _                       "by increasing the GRID-SIZE-X or "
; d9 ?" o$ n( @0 ^6 a0 M6 h4 U                       "GRID-SIZE-Y sliders, or decrease the "5 q1 }1 v& ?# s
                       "number of cars by lowering the NUMBER slider.\n"
  j$ g7 p6 x0 K: n/ n; w                       "The setup has stopped.")' j; Z5 ?9 s2 p  _# a9 i
    stop( e0 T7 p3 u7 E. ]
  ]  ]! {  |4 W9 @

1 S; g6 G4 z- n0 }$ \4 z/ C" N  ;; Now create the turtles and have each created turtle call the functions setup-cars and set-car-color& N& X+ i3 Z( C6 U" n7 m
  crt num-cars% m2 L8 w2 P/ d- u- m( [* Z& z
  [  w; O, |! T; J) z. F: {' u) Z' E/ r0 G
    setup-cars& s8 Y* u# O- K0 j3 h- z' ?0 O
    set-car-color
9 \6 m3 b: `, E/ e; h+ S  m    record-data
! {3 N7 b+ P9 h+ |9 q8 W! `1 p  ]- \: f' ?9 w; ]9 G1 P9 ~  L
8 p, a# V2 ]1 f7 L' s& A# ?
  ;; give the turtles an initial speed
* H- K, s9 q6 S1 ?, J" Q# b  ask turtles [ set-car-speed ]( J& Y) `8 k8 s4 q( X& Y5 ~  E

6 h2 y4 b- Q% G) W2 h7 L. G  reset-ticks
5 I" v" D: T9 z( W! y1 P" hend
' X$ ~# R6 y: U1 ^& ]; `: T$ e" N( u* q9 a' @( \1 o1 |
;; Initialize the global variables to appropriate values
/ r0 }, {: s( P: e2 \* j1 j: s2 yto setup-globals( f, g" X% p3 j6 g; b6 b
  set current-light nobody ;; just for now, since there are no lights yet
: ~3 i- {6 a; P# F( D  set phase 0
: z* r3 E1 _8 Q7 C4 K, Q  set num-cars-stopped 03 w4 T0 R* ~0 @
  set grid-x-inc world-width / grid-size-x
* n: G' u5 x9 [% _+ {  set grid-y-inc world-height / grid-size-y
8 E# G( _$ J+ G1 {9 |- V3 U
# l) F( w1 y* o" u8 J/ u  ;; don't make acceleration 0.1 since we could get a rounding error and end up on a patch boundary
" ]) y; K/ Y# Y  set acceleration 0.099
+ s# |9 }+ }% \4 send
' y$ {1 S$ A+ k/ ^2 G- h$ b
1 p, |. Z- S% ?1 k, \0 H;; Make the patches have appropriate colors, set up the roads and intersections agentsets,0 W  ~7 w* m. E5 e$ |8 n* x
;; and initialize the traffic lights to one setting6 c) a5 Y1 t/ ~% Z. ?6 B
to setup-patches" B. s) N8 j  K- e' u  j
  ;; initialize the patch-owned variables and color the patches to a base-color
" F! {2 X- F* Y* ^* L' ]  ask patches6 q3 F/ Z0 N/ @1 a
  [+ b+ r2 [! m0 Y& U
    set intersection? false
% `9 q4 Y5 Y: |: t    set auto? false! `0 y% @: L* ~8 `
    set green-light-up? true, Y* x' @$ Q( P( \! {
    set my-row -1
8 S& ^2 j; H  h% Y2 j    set my-column -1  V. B: P! R) u! c4 e0 r. i
    set my-phase -1
; ^  I3 g5 R( G5 h& ~    set pcolor brown + 3
3 J8 ]% U( }& D2 {$ a; v& a  ]* t$ L. E/ P+ W% j

) f2 M5 ?4 @2 M$ Y. S# C  ;; initialize the global variables that hold patch agentsets
4 W; P0 R, D, S1 K4 T+ U  set roads patches with- ]( r$ X3 l# g, z$ r
    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) or2 X0 w6 {( M3 x) a+ F8 ~
    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]
( N. ?  K. r8 F' N% u  set intersections roads with' a3 g" ]/ u6 b9 f& g0 U4 D# B
    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) and
+ O- w: |, }1 }2 M    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]
4 z. _1 R& _6 s1 }2 l1 y5 R, p$ T7 M3 B
  ask roads [ set pcolor white ]
3 ~0 U0 g' Z( N, N- K    setup-intersections
  ^2 C# Q+ Q9 V0 ~$ y+ Gend
4 J- l2 n& b- a& Q其中定义道路的句子,如下所示,是什么意思啊?
* Z/ _9 T' _2 m# W: A- v set roads patches with9 O( \6 F4 g; A; j, z
    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) or" K8 ?# |+ O5 b; }# o: I4 e
    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]
& @* c4 s5 \% o6 ^) {7 |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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