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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。; ^3 u8 U* [* ^$ `$ G( ]
netlogo自带的social science--traffic grid这一例子当中,& U* S) B8 R* x- R5 |6 G! g8 |7 C
globals+ \1 f( x9 i3 O/ \2 |& t! y4 B
[
6 ^" l1 I7 Z( _/ k2 u. c# p  grid-x-inc               ;; the amount of patches in between two roads in the x direction5 F6 w; ^7 u* a* b5 f% J
  grid-y-inc               ;; the amount of patches in between two roads in the y direction4 a; z7 i9 ~- i8 y1 ]0 v
  acceleration             ;; the constant that controls how much a car speeds up or slows down by if" M0 e9 F. f7 s1 h  o7 p
                           ;; it is to accelerate or decelerate# @: c+ i- W' O/ Q
  phase                    ;; keeps track of the phase2 T! ~, X) |/ P3 u7 r
  num-cars-stopped         ;; the number of cars that are stopped during a single pass thru the go procedure4 B( ^8 |: v3 \
  current-light            ;; the currently selected light
4 X5 E4 K8 d0 s
8 \! V) q1 F; |  S6 a0 F- b  ;; patch agentsets
# r- ]6 W9 S2 y5 }& E& K  intersections ;; agentset containing the patches that are intersections
( I* a( s6 f& u  s( [' ]( L. V  roads         ;; agentset containing the patches that are roads: K" k8 f4 j; n2 ^
]& l0 _  e, f" Q6 X0 W+ c3 ]

: d, `, o( ^# Z& r6 v+ [turtles-own5 k5 ?) a- c/ {* M8 i9 f$ J
[8 }; T3 |4 U/ z! D- O5 y
  speed     ;; the speed of the turtle
4 d3 z$ P; t4 K- n" a0 G  up-car?   ;; true if the turtle moves downwards and false if it moves to the right: f2 f& A+ z1 \
  wait-time ;; the amount of time since the last time a turtle has moved7 N$ ~3 E0 F' B9 q) Q& ~. @8 R" e
]9 s2 H6 p; W" y, G# I
2 M. J  p6 R: V
patches-own  T7 P' ^: I# V: o- r
[
1 F0 O* ?9 u( O( `  intersection?   ;; true if the patch is at the intersection of two roads
0 s* L: a. X0 S  q5 ~. m: ?  green-light-up? ;; true if the green light is above the intersection.  otherwise, false.5 p& W! l: C# s. ~7 N2 a. c
                  ;; false for a non-intersection patches.5 i& C. U4 M( S& x
  my-row          ;; the row of the intersection counting from the upper left corner of the
6 y. P5 z' ~* s) W. S* X. ^                  ;; world.  -1 for non-intersection patches.
3 h8 L* A9 b7 C' I. e  my-column       ;; the column of the intersection counting from the upper left corner of the
/ J4 _- B: }9 j                  ;; world.  -1 for non-intersection patches.
( v6 Y. w8 Q: U8 s( I, E$ D  my-phase        ;; the phase for the intersection.  -1 for non-intersection patches.
/ ~/ s: A/ `2 x6 T0 h6 _. {  auto?           ;; whether or not this intersection will switch automatically.8 W4 j( _2 {, h" k
                  ;; false for non-intersection patches.9 n" U! O  _/ @- Z0 j  [8 @" G* W
]' A6 S& I5 `$ r5 f$ u8 u7 E
' J$ a. n" u8 h1 X: O# U  e

) t, |& ]4 [/ H8 ~9 Y;;;;;;;;;;;;;;;;;;;;;;
4 {* E1 m! B, j& [5 b;; Setup Procedures ;;4 P& Y9 g" l4 q# C
;;;;;;;;;;;;;;;;;;;;;;2 @/ r9 O" Y/ S4 v& R
% _+ J. q# r9 ]4 Q
;; Initialize the display by giving the global and patch variables initial values.
  L5 L, d3 y; T4 g: C8 n: j$ c' [; Q;; Create num-cars of turtles if there are enough road patches for one turtle to
4 I1 [7 V) N% u/ v. E  K;; be created per road patch. Set up the plots.
+ l9 k1 R$ n3 dto setup2 G' H2 h0 Q" E+ o$ z2 c( |! r
  ca
$ A! ~+ p$ K9 Q' t' ?% W- S  setup-globals
* ?* c! W$ W/ _0 _0 e# p
; |9 z) B: g  H* S  ;; First we ask the patches to draw themselves and set up a few variables
6 U+ X) m) W' W2 C  setup-patches
4 N/ ?- z: ]  d: g; a  make-current one-of intersections; \) `; W- ~- t/ r% K: S: w1 O
  label-current
+ k2 c9 N- Q9 n4 n/ I& [& ?
: b( v5 a/ G8 O  set-default-shape turtles "car"
9 C' [, S. ?* `2 ^1 W* e% E6 f! Z
- N  b* ^9 c6 F. M! ]' `2 {! }: T  if (num-cars > count roads)
0 d" p1 i  d/ O- W' x3 x  [! f6 s8 {, O2 u, ^- C8 n+ v
    user-message (word "There are too many cars for the amount of "$ T% P  [: O3 ?- K  b5 ?! N& f
                       "road.  Either increase the amount of roads "0 l$ d" h! N% D! X" b6 n
                       "by increasing the GRID-SIZE-X or "1 V' p4 R( q* }. w& M
                       "GRID-SIZE-Y sliders, or decrease the "& z: ~* r3 Z' o* D* r- m1 t% K: B6 q- W
                       "number of cars by lowering the NUMBER slider.\n"0 r& u, m# L) k
                       "The setup has stopped.")
8 t, U" Z9 E$ M% v; H    stop0 \8 h' O$ j9 P6 o2 K! v3 m
  ]4 Y+ l4 S! l0 @3 |+ d3 ~2 P) j
3 N' y% D+ b% J( g
  ;; Now create the turtles and have each created turtle call the functions setup-cars and set-car-color/ d, Q3 M; ~9 ]/ t. I
  crt num-cars
! |' S; z: ]7 j" E. Y1 F  [
/ c6 w' d; D8 l1 V- i! ]    setup-cars
& F. ^1 Y/ X& }    set-car-color. f7 D- N+ v1 `
    record-data
4 p$ v+ E+ b* ?  S+ G& A. q  ]
( v7 ^1 p$ S% ]. H1 W! U# L( Y$ b' _- f1 o& e1 G1 z0 v& X
  ;; give the turtles an initial speed
6 [; B! H% f3 |" W1 {9 t& y  ask turtles [ set-car-speed ]+ [( k* g$ B# o' i  I

8 K0 }3 T# y' G( ?9 m# S. y  reset-ticks' L: W" j% r  x3 W* O! w
end6 k% `- ^' C  h& R2 f% a

# v" U- b+ _: q) E* {& {/ `;; Initialize the global variables to appropriate values* N) E& r" P* n* c
to setup-globals3 _; Q- R! b/ a  U0 I. q
  set current-light nobody ;; just for now, since there are no lights yet
- _2 I+ t5 M' @9 P5 @3 o/ ?! W  set phase 08 z* U- `7 }( O0 n# U7 c
  set num-cars-stopped 0
/ [4 H. ~$ H" I  P( l  set grid-x-inc world-width / grid-size-x
- V$ U2 ]% F6 X5 k  set grid-y-inc world-height / grid-size-y% u+ \8 M0 h' f

: f. }) f; @6 O6 d& v4 f  ;; don't make acceleration 0.1 since we could get a rounding error and end up on a patch boundary
; A6 r/ l8 V, x8 Q7 Q' l0 S  q. B  set acceleration 0.099
  G6 r( K2 a6 {* w' _' G$ }7 aend: v- A6 f6 M2 G% I+ `
7 G# [! `- ~% c  q1 b0 V* R; v% O6 _
;; Make the patches have appropriate colors, set up the roads and intersections agentsets,) ?% Q* c- M! v1 i% o: D3 h
;; and initialize the traffic lights to one setting) g3 m  e# c" p& I) D0 S( I- X. ]
to setup-patches" P; ?$ {, y' R) `* U* u* A
  ;; initialize the patch-owned variables and color the patches to a base-color% E+ p4 I% n2 v8 s, m' P4 O9 N
  ask patches6 M" W! H; [& U' }% `; T: k) x
  [& Z+ t  o  y! f8 |( _$ s) U5 @8 h
    set intersection? false
* N# i* q, F4 t7 j) Q( \& V: r    set auto? false
7 B3 \, d2 J5 x3 Y8 h    set green-light-up? true
( F" O$ X- U  F4 ?3 S* O1 }: T    set my-row -1& {, v5 L) @3 V* c+ `' C
    set my-column -1
/ B0 D7 I# ]3 g1 v, g( C. _    set my-phase -1) F! g# h9 r) R) W
    set pcolor brown + 3
$ ^, o! q8 d, M0 n( k  Y  ]
9 L) S9 w7 j1 N4 s2 K0 W0 }+ u! e9 l$ e
  ;; initialize the global variables that hold patch agentsets3 u* \/ ]$ H2 D# d$ q: j4 e4 i" y1 ]- }
  set roads patches with' @8 |4 E; z/ H' Z4 @
    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) or* t2 W/ ]: Q4 V- O: W& M, K
    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]
. U6 I. h* x' |  set intersections roads with/ d6 g9 e& {: G% N
    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) and& s$ t5 D$ @. l/ ~
    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]8 k. x0 R! B$ j" m
# [$ N# o; E, N
  ask roads [ set pcolor white ]
" M: @5 s* H* `# x$ |1 z# Z    setup-intersections
; O! m2 O5 Y5 u5 t! f) ^end/ t8 Z  J" i# p- h4 Y4 E
其中定义道路的句子,如下所示,是什么意思啊?
- ], I! q) n/ W4 ]! L1 X set roads patches with9 s6 Z( |& C. Z: _, |  x$ a
    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) or
4 |: p. a  X4 G5 h    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]& R9 f3 Q5 ~9 U( O+ 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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