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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。
, q% _* w  Z) `3 J; [netlogo自带的social science--traffic grid这一例子当中,5 k( v1 Q6 B2 T( D% I
globals" b, P* o7 e! ]. T" X, Y
[
3 N0 Z# O; y8 X5 a% K) f  grid-x-inc               ;; the amount of patches in between two roads in the x direction
% F/ y5 U7 o4 D; }8 s- g  grid-y-inc               ;; the amount of patches in between two roads in the y direction  O* ]7 X$ j- L1 o& l: O
  acceleration             ;; the constant that controls how much a car speeds up or slows down by if7 N2 e0 s$ C5 u
                           ;; it is to accelerate or decelerate
+ ~4 a9 p5 y; i/ ]  phase                    ;; keeps track of the phase
0 U, q" o* G7 O( o9 L  num-cars-stopped         ;; the number of cars that are stopped during a single pass thru the go procedure9 f' e) _5 h+ @( v4 u
  current-light            ;; the currently selected light7 W( X* {4 R# P, u' j) w/ H  l

! F5 J! H# p  ]3 r9 F4 z/ v! D5 q  ;; patch agentsets" Z4 V7 p/ m9 b5 ?( f& z8 n- R
  intersections ;; agentset containing the patches that are intersections* l2 u/ P- G8 w" @5 O5 v
  roads         ;; agentset containing the patches that are roads
2 T% O: c* l( i& P]& N! ?2 O0 d! a7 j$ o3 p" A

3 i) E/ c* p! l) q7 Tturtles-own
4 b" R! F, Z1 r# S6 |: H$ P[
6 B* d  p" d+ k; W4 ?3 Y' E5 q3 G  speed     ;; the speed of the turtle! K. l0 u- d2 e$ {( Z7 X
  up-car?   ;; true if the turtle moves downwards and false if it moves to the right$ v; B7 Q+ S9 a$ r
  wait-time ;; the amount of time since the last time a turtle has moved: @& d8 o2 Y% Y
]
3 N  |& n: c; T6 R7 b1 {6 U; p2 F# e/ p! o
patches-own
' \3 s) _- _2 \0 T) `* }[1 e2 _  u% M. N( k! `+ }
  intersection?   ;; true if the patch is at the intersection of two roads
( c$ Q1 g' R( P' J7 |* B$ Q  green-light-up? ;; true if the green light is above the intersection.  otherwise, false.
7 c6 v4 k- A" ^# f/ n$ o& ]. M                  ;; false for a non-intersection patches.
0 v2 c. P+ B; H( ^9 Q( G, u1 b) P  my-row          ;; the row of the intersection counting from the upper left corner of the" K& U( s- r/ L% A, p' w- `
                  ;; world.  -1 for non-intersection patches.
+ R* Q/ S3 x7 o' J4 O8 P  my-column       ;; the column of the intersection counting from the upper left corner of the7 ^% ]8 x' @2 N2 V$ g! d- K
                  ;; world.  -1 for non-intersection patches.
8 Z( v9 F) v$ o% e0 O# Y4 [$ s  my-phase        ;; the phase for the intersection.  -1 for non-intersection patches.
* m( ~+ D# z' A* z* z: @  auto?           ;; whether or not this intersection will switch automatically.
9 Q8 A, ?8 w9 f3 f. c                  ;; false for non-intersection patches." B" b1 D" x0 n1 X4 d9 o
]" A6 D& T8 J* b* H* a

) S. q3 u8 G4 c! F1 K" x
1 I3 F9 ?, R* y# B4 U; Q;;;;;;;;;;;;;;;;;;;;;;
- {& _0 t2 m1 z5 n( I;; Setup Procedures ;;
+ ], f% P2 x5 k/ y  ^7 n7 [* f;;;;;;;;;;;;;;;;;;;;;;& O$ M' w: Q0 `0 J

' ?: e7 O# u6 j$ F4 [. G% \;; Initialize the display by giving the global and patch variables initial values.
# B. E( W9 T4 k;; Create num-cars of turtles if there are enough road patches for one turtle to
# _- E7 X* M* Y' l;; be created per road patch. Set up the plots." c+ j1 O9 R  a8 b
to setup% e$ ~4 e+ J# U4 f( Z# O
  ca; k4 ]% \: o+ T- B: j7 w
  setup-globals
4 A. p$ B6 l0 I+ u
) B  \" z) ?5 t  ;; First we ask the patches to draw themselves and set up a few variables
% L: S& _( K8 c1 _  setup-patches
$ T( e. C$ \* P. |/ k* k  make-current one-of intersections$ p9 r9 M8 F1 e# w, C
  label-current
3 J9 X( V" d1 F5 I% v+ K: F7 T7 @' w1 Q+ I& l+ C
  set-default-shape turtles "car"( Q7 [7 g* E( Z' ?7 k

3 @$ y. f3 x. C  if (num-cars > count roads)% R8 h: u4 }5 i; t& Y
  [
( A# Y( q6 J  Y* M* v9 w8 C    user-message (word "There are too many cars for the amount of "7 B6 W9 h; T  [; X8 ^: A
                       "road.  Either increase the amount of roads "
; x$ w9 F; N% |% l                       "by increasing the GRID-SIZE-X or "
. ~# O: _$ V% _, ?( b5 G                       "GRID-SIZE-Y sliders, or decrease the "
. |8 W! j  r& v  v3 V                       "number of cars by lowering the NUMBER slider.\n"
) @/ j/ g; _& e9 v6 Y0 r# d; B                       "The setup has stopped."), C1 w1 t3 W- t4 X* Q; h, ~
    stop
% Z5 [9 ?6 O+ G& s0 v4 q  ]+ |% R& P( ?3 ^; k
0 R) E6 {$ i2 A- |! p8 H& A% ]# K. u7 t
  ;; Now create the turtles and have each created turtle call the functions setup-cars and set-car-color
" _( f4 T" J$ L# H2 i$ K  crt num-cars
: Y& I$ _3 \% t+ K  [
$ M- W- Z, q- D3 Z    setup-cars% a- m* E* ^# D
    set-car-color. N; \; ]; q0 M& h3 u# }+ k) _  L
    record-data& I! O' S$ g% e( n# H" ~- N  g" O
  ]
9 Y6 F5 v0 ]+ k, `$ z. d- E( h6 e* J# {0 b( M& m& V' L# F* b0 c
  ;; give the turtles an initial speed/ O- k0 S1 G3 y9 x0 y; r: v
  ask turtles [ set-car-speed ]9 v& j) Q, W; I9 `* u

, L. B% R6 i; J9 N9 M7 n% W2 d6 s  reset-ticks
- x0 U% m/ y( N+ l  ^$ Z* s1 Bend
$ ~& x6 X6 ]  I% i+ ?7 {! h0 L  S' r: i. m
;; Initialize the global variables to appropriate values+ T) ]! y; T& |8 l2 p% ?
to setup-globals
+ v. F, e& d9 `9 k& Q  set current-light nobody ;; just for now, since there are no lights yet$ T% C* q) B2 f  Y4 z1 P
  set phase 0
) O3 e' Y& [: ]& G5 D0 {# [  set num-cars-stopped 0
+ ]- a2 ~1 M2 K% f2 p  set grid-x-inc world-width / grid-size-x
3 C1 ~; q6 M! m/ ?  ]" X  set grid-y-inc world-height / grid-size-y- b) h2 w6 s, E  Y3 Q) t
9 B0 x$ m+ K1 H6 N6 \
  ;; don't make acceleration 0.1 since we could get a rounding error and end up on a patch boundary5 H+ A: `# R5 T0 t  G
  set acceleration 0.099
5 u5 |( a. s  \7 U& lend
6 H" y( @6 Q. D1 X9 w2 X
& i, e7 h/ x2 p: n;; Make the patches have appropriate colors, set up the roads and intersections agentsets,0 `; P% {+ x  O0 m  s  j, I, y8 L
;; and initialize the traffic lights to one setting+ N# X5 h% h/ E. q- O* e- ]* w* x9 W: L' ]
to setup-patches
" ]7 s; Y" z7 y# j  ;; initialize the patch-owned variables and color the patches to a base-color3 c0 ?6 _! }2 P4 ~9 e3 V$ B
  ask patches& w* R( J1 t3 b& _( ]6 B; G- Y/ Y) Q
  [
) U+ ?0 {+ k# ~/ U+ t! P1 \    set intersection? false
; ?4 a. o+ p4 L$ _( I+ l    set auto? false
4 c; ~' T" S: E    set green-light-up? true1 i* ~' x2 T; K3 H7 `/ v7 A
    set my-row -1
6 a2 g+ x) c- m3 `8 y. J% W    set my-column -1* h* p. ]- c( I  r/ y% `4 `
    set my-phase -1
8 q1 J1 p6 j* B& Y( ^* B    set pcolor brown + 3/ S( y( z. @9 z, q" y
  ]
2 Z0 O5 x7 w8 Y( `0 B9 \1 O) X. l2 \( L* j0 t2 Z. D
  ;; initialize the global variables that hold patch agentsets& W& p* |# p( @4 O
  set roads patches with
; }' l  Z0 w3 c% V% K    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) or
6 \9 ^3 X0 i: U! W& I    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]
5 ?; h. w# M& Z7 \$ V. H  set intersections roads with: M! G% G. A6 h1 Z
    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) and
. `' o# m; u* z4 f) z    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]
0 T) v) k. O3 ^$ h+ k* Q4 _) _+ B% N" H
: ?( z6 @& }. Q+ ?3 V  ask roads [ set pcolor white ]
5 B. H0 ^. r% _  u5 `) R, ]    setup-intersections
4 K& O0 b5 k: j* x) pend( f2 B- }% ?7 \& R1 w
其中定义道路的句子,如下所示,是什么意思啊?
) k% b3 ?; U( ]  a7 d0 h, {* ] set roads patches with
3 j5 h$ l3 b! W$ m" {: _* u% N0 f* Z    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) or+ L- m. _" B6 [
    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]# `) y. S( r; M/ f* S. ^
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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