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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。# w: ~$ }% k# ~7 v
netlogo自带的social science--traffic grid这一例子当中,) S9 |4 |/ e% n5 c
globals' M- P3 T3 r9 \6 j6 H
[: W0 \/ o/ K7 O- r  {0 `  c, S! |
  grid-x-inc               ;; the amount of patches in between two roads in the x direction/ r7 ~( f2 b2 ?$ K( y; P2 f2 L2 q
  grid-y-inc               ;; the amount of patches in between two roads in the y direction+ [$ u4 V" K6 T
  acceleration             ;; the constant that controls how much a car speeds up or slows down by if1 c' z& ~- D+ E& `, q
                           ;; it is to accelerate or decelerate
! I1 e5 V. u( z' r3 {  phase                    ;; keeps track of the phase0 @1 Z* P1 f& M/ w. ?
  num-cars-stopped         ;; the number of cars that are stopped during a single pass thru the go procedure
8 t+ H. s  v, i- t  current-light            ;; the currently selected light2 ?7 b( p0 Y" |, x( P  w

) F3 G, H) r; v) @" R' m. P# M% n  ;; patch agentsets
: D) n4 M* F& e& |  T  b7 ^" w  b  intersections ;; agentset containing the patches that are intersections
0 V# B& m/ {2 s8 L( \3 V  \/ g  roads         ;; agentset containing the patches that are roads: I* A4 H( @- \* a
]) R$ F/ Z4 v& |: g/ ?; z
' {* Z, _  \% X2 @
turtles-own+ g1 }- c0 X  {3 a1 \
[
9 B, Q2 N$ i+ o, U, T  ^  speed     ;; the speed of the turtle7 z4 k1 L' _7 w' x
  up-car?   ;; true if the turtle moves downwards and false if it moves to the right& H# S' Z! |2 k; z4 O8 u4 h
  wait-time ;; the amount of time since the last time a turtle has moved
8 i( M; q: B! k2 A" I) _]
- P: }+ u9 z6 U! w) r( W7 g
7 W9 u" _& {; F4 _' V5 ypatches-own
$ n, l; I) @: y( B& G( V$ ~[" L3 H' N5 H9 }& t! a( L: O
  intersection?   ;; true if the patch is at the intersection of two roads
/ ?  ^% X: i! E+ g  green-light-up? ;; true if the green light is above the intersection.  otherwise, false.
  h- y- r+ Q; K, ~                  ;; false for a non-intersection patches.
4 t# V- n1 U! Z0 v  my-row          ;; the row of the intersection counting from the upper left corner of the- l# `( J6 X; H$ V) H
                  ;; world.  -1 for non-intersection patches.
7 b" k# U6 x0 i+ r1 S  my-column       ;; the column of the intersection counting from the upper left corner of the. J9 S, F* Z. N$ s: r! N* ^
                  ;; world.  -1 for non-intersection patches.
; e  Y1 Q! @- G! H! |# z  my-phase        ;; the phase for the intersection.  -1 for non-intersection patches.1 E: H% j4 n  l) V
  auto?           ;; whether or not this intersection will switch automatically.5 i1 A: y9 h* Q3 m3 Y; a& ^4 k
                  ;; false for non-intersection patches.+ Y9 c; a; E( Y% I8 A2 m6 ~* T  J
]3 J( j. y( \& I; M: o* \6 ]
4 Y" Y  U! f6 t8 P
7 k; ?3 S) d$ ?1 o! r
;;;;;;;;;;;;;;;;;;;;;;
" D! o, {: K  c. K1 C9 |" o7 {3 H; c;; Setup Procedures ;;, z; B  c% j, R) c. N) C% o* _2 k
;;;;;;;;;;;;;;;;;;;;;;: T0 b' W5 W% W
5 C) N% y' }) V7 E
;; Initialize the display by giving the global and patch variables initial values.
6 V) K% m4 N' a;; Create num-cars of turtles if there are enough road patches for one turtle to
3 `# \: d8 |; P) @;; be created per road patch. Set up the plots.
1 A0 ]# v6 ~( e: }to setup+ M7 p5 k8 y/ u2 a" X- y9 u
  ca3 s, E6 P: f' ~4 C# f! Q4 E  h8 g
  setup-globals$ [* t& a6 w0 h# q+ e3 [3 E

, @1 }1 C( J1 ^! x4 L( e5 ]  ;; First we ask the patches to draw themselves and set up a few variables" M3 r- S6 o( r, E
  setup-patches
5 N! J/ ?- g4 P1 x  y8 A  make-current one-of intersections7 I5 c& M2 e. Y- g% S
  label-current% m# S1 \: k0 W
* A5 J+ Q# T# Q: t! ?
  set-default-shape turtles "car". a# K% c) p0 H" Z+ W. d- x

+ l4 C% \3 k3 b7 ~  Z) _  if (num-cars > count roads)
% n" m7 u, C7 \! {, o  [
5 i1 n2 a% P5 ?7 ^) V% Q1 A; n    user-message (word "There are too many cars for the amount of "
& n7 o9 b$ K( U9 Q8 V' d                       "road.  Either increase the amount of roads "
) K# ?0 U% [* ^! K2 K: r6 M; T& |2 o3 L                       "by increasing the GRID-SIZE-X or "
5 D3 O0 d! z3 j, T$ ]8 l                       "GRID-SIZE-Y sliders, or decrease the "+ T; D7 a6 O8 }) j1 U/ K6 W
                       "number of cars by lowering the NUMBER slider.\n": q! k. C! D, {" U/ H
                       "The setup has stopped."). e, i; x2 Q0 c4 K: K# P0 z
    stop- n( z5 H4 H$ Q0 `' U6 l4 D/ R
  ]
; \1 S6 X0 Y" L" [* p( y: s- d( C4 g- A5 `
' e6 `7 i, t, P( y4 T: K* {  ;; Now create the turtles and have each created turtle call the functions setup-cars and set-car-color
; u6 F+ [% d) r3 ]! M* }8 y  crt num-cars  |/ c% |2 S/ R6 F- h
  [, u  q) o) @' @3 ]+ [/ E) s9 N' T
    setup-cars
: g3 H4 N! G' }! Q; i0 W) B    set-car-color# l2 e1 i) W3 H5 B" a
    record-data
! j. M) y1 T6 U( j/ C  ], o  M* w0 z/ a* p: a! Y

/ k+ E1 X' N8 ?6 W: }1 ~  ;; give the turtles an initial speed
; B. w( @$ V. C/ r$ u  ask turtles [ set-car-speed ]
. R% \+ {; `0 ^* S6 k
$ Q  y$ O% p2 i5 H9 g, g1 W  reset-ticks
" `! |& X+ X+ L. r/ oend$ h5 ~! K/ Q4 |, U9 v1 ?: g
/ z' d2 I" M- U/ N
;; Initialize the global variables to appropriate values. H+ a$ Q9 ~1 g' X% ^- v
to setup-globals
" H/ ?- m. N6 Z6 v0 u  set current-light nobody ;; just for now, since there are no lights yet
4 [! D( S7 Q# T4 q  X& T  set phase 0
) x. ^  e6 {9 {& k  set num-cars-stopped 0
) Y0 |5 J; G3 V  set grid-x-inc world-width / grid-size-x1 a$ H; K; E: V
  set grid-y-inc world-height / grid-size-y
4 q9 l5 p5 k! P0 d1 a) _$ O- P
4 B3 Z5 G1 h* M  ;; don't make acceleration 0.1 since we could get a rounding error and end up on a patch boundary, J1 R! I1 J9 c0 z
  set acceleration 0.099
2 h5 @, t$ G1 Q# wend
! B  K( m- q8 H+ G( J, n* s- @' f% m8 x" s
;; Make the patches have appropriate colors, set up the roads and intersections agentsets,
6 e; G  `2 U) q) J/ a! B& {4 D;; and initialize the traffic lights to one setting: n8 T" C' `6 Q( T3 s" g
to setup-patches
; a3 o3 j9 b; [! q5 Q: s0 p+ g/ o6 R  ;; initialize the patch-owned variables and color the patches to a base-color
, Y5 k" S  @* }5 G1 L2 x. @, B% _  ask patches
* s% b. u' F: n0 P3 x. w' }  [
" n5 j+ B/ k- Q" Q3 N    set intersection? false3 [8 Q9 U) a* e
    set auto? false- g# f- I# U8 C1 m* }) U# N7 I
    set green-light-up? true# S3 P+ E/ d! W
    set my-row -1
: `: U9 J  o0 h, J- |! k& g    set my-column -1
' u  g2 q/ ^4 d- e    set my-phase -1. r7 g* @7 b  I0 q2 V
    set pcolor brown + 3  C3 n! o$ q+ W: q6 a
  ]+ R( B+ a* H7 W8 [
8 f' B, K0 j; s* t5 W) @
  ;; initialize the global variables that hold patch agentsets
4 [6 M( C4 ~4 T* A  set roads patches with, U$ R' i  r1 i9 Y) E6 ^- y
    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) or8 q3 h1 a+ U8 k- D
    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]' i0 Z# J0 o0 v) M. Y4 C
  set intersections roads with& M; M# ]% g6 L: i1 i. P2 C. S
    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) and4 ]! B, n7 O8 M" w. ?/ ~9 J5 F* I
    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]* _; C, Q3 `' ]9 p

7 _  A1 S$ q1 {  v  b  ask roads [ set pcolor white ]6 W, ^9 {$ G! u' F
    setup-intersections9 M( E+ S; C2 p! ]
end# A+ y9 O: L: w6 l
其中定义道路的句子,如下所示,是什么意思啊?, [3 G3 v# V$ u( c  v  O/ }
set roads patches with
! u- H; G1 o, s6 I" ]. Q% K    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) or& O: b: X. o7 O) }8 l
    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]
7 E! [; s* d) F- M4 w6 Y+ r8 M1 X4 p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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