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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  i) c) V: I) u
netlogo自带的social science--traffic grid这一例子当中,
2 N* e" v. e9 v1 I2 X0 aglobals
/ \9 J& Q' C- r% q9 w) U% G[: h5 h  b( P* X' ]3 B9 H  i. L2 @) @
  grid-x-inc               ;; the amount of patches in between two roads in the x direction
1 o" t$ b" i; E( O% h, z/ C4 B  s: k  grid-y-inc               ;; the amount of patches in between two roads in the y direction
& ]$ b' e7 N5 D" |& A# X  acceleration             ;; the constant that controls how much a car speeds up or slows down by if- I* c: e  l# ]7 B3 r* j  E
                           ;; it is to accelerate or decelerate- T. |8 k/ C8 A# f0 F
  phase                    ;; keeps track of the phase7 C! z# L( p# a6 d! j9 N7 s2 A! c1 f
  num-cars-stopped         ;; the number of cars that are stopped during a single pass thru the go procedure/ e$ n0 Z2 |  d8 g+ R; Y" N0 \9 Y
  current-light            ;; the currently selected light, k  S# A8 ^- S5 X( F# X0 L" V- F

1 s( ^$ x. L4 T8 I+ t- j0 l  ;; patch agentsets
7 H+ ^; t% t1 V% E/ J* y0 x  intersections ;; agentset containing the patches that are intersections) y5 J+ s6 e7 @! }1 E; j
  roads         ;; agentset containing the patches that are roads0 B- K% z. |: N
]3 W+ C+ A2 R; w' t0 {$ w! c) I
8 h; ^5 T0 o+ O
turtles-own
# ]3 H" O3 W/ g, N$ F, C[
# s( F1 q0 u( K  M9 t8 t0 M  speed     ;; the speed of the turtle
% V0 v: s: v7 F2 r3 J  ]  up-car?   ;; true if the turtle moves downwards and false if it moves to the right; q+ ?1 d+ H: {9 T9 A4 l& U+ m' K8 G
  wait-time ;; the amount of time since the last time a turtle has moved
; @2 V, T/ m, t# H( p]
# x1 R+ T* ]1 F, P& B! D# q, x6 K7 `3 L
patches-own
. J9 s; L( p$ n# d. V" @[
/ g+ C  |  W1 T  intersection?   ;; true if the patch is at the intersection of two roads
3 ?+ f: s) Z0 d  green-light-up? ;; true if the green light is above the intersection.  otherwise, false.# _# q, L6 V) b0 ^3 e
                  ;; false for a non-intersection patches.
* I. n' ?/ F: I( l  W5 B  my-row          ;; the row of the intersection counting from the upper left corner of the# i. p9 j1 o# e" {* \3 Z' B
                  ;; world.  -1 for non-intersection patches.
0 a/ x0 {* V! D3 @  my-column       ;; the column of the intersection counting from the upper left corner of the3 M0 U7 h- k( @5 G( `
                  ;; world.  -1 for non-intersection patches.
8 v( I% O3 g/ B% V  my-phase        ;; the phase for the intersection.  -1 for non-intersection patches.$ _5 ~4 n* d* r
  auto?           ;; whether or not this intersection will switch automatically.
0 ]2 L6 h( z' N" q5 q, @5 V6 l, {. \                  ;; false for non-intersection patches.
' D5 U. F& w' x; }  F" w0 j]
7 \+ @$ A. L3 n% F+ o  B& g
* L7 ]3 _! e% d4 P6 d/ [4 X# P4 I7 \; R. I* s/ p9 I. T
;;;;;;;;;;;;;;;;;;;;;;
4 m# n) z, [7 S* y5 t0 K8 r9 };; Setup Procedures ;;- T! q9 J2 m- g! Z
;;;;;;;;;;;;;;;;;;;;;;9 ]& B# |9 c8 n' t
( q. N9 r4 n9 g8 X1 v1 P
;; Initialize the display by giving the global and patch variables initial values.
8 _) j& }9 o6 @1 t;; Create num-cars of turtles if there are enough road patches for one turtle to$ J& E* ?) Y$ t# g0 ?- U' W
;; be created per road patch. Set up the plots.. C9 j0 }: N, o- Y2 i' }
to setup
. v; d  y+ `! h( ^- J, z  ca
  Z# {' v" M8 o& \  setup-globals/ Y/ Q/ I2 h. D/ a2 B. r

+ x# h$ d$ K& q2 j6 W' ]* V  ;; First we ask the patches to draw themselves and set up a few variables9 `. B1 R! e8 ~0 M! M3 M' ^
  setup-patches7 J% s# I/ {, Z3 l- O
  make-current one-of intersections
9 t# l3 c; O' a# L  E! y! [8 w! `2 `  label-current$ n0 h+ q  W* H# M# J

& k$ L4 }; K1 A5 @! X* v, l  set-default-shape turtles "car") ?6 o9 p0 X5 [# I9 B. a5 w

9 T* }, G" [( Z  if (num-cars > count roads)
. w$ y% _; W. U* [1 e% b7 R, J5 i  [' g0 @  ^; S: Q7 d
    user-message (word "There are too many cars for the amount of "
. x( L) @+ p2 F* c' f& J; g                       "road.  Either increase the amount of roads "8 R$ J6 _; B7 |) l4 A
                       "by increasing the GRID-SIZE-X or "
3 h& I1 g# z& b/ f+ g                       "GRID-SIZE-Y sliders, or decrease the "8 R; i* @& M2 i$ P$ w- y) ^$ {  G
                       "number of cars by lowering the NUMBER slider.\n"
, M3 f. h; ~0 k* {                       "The setup has stopped.")
2 X# ~! [5 s1 \' b0 N# m6 d    stop
' m. a' W7 {: T, q2 q1 ?  a  ]. P5 [" y$ U, t1 p4 T& i
$ k( g. g% @- @# o) ]9 u
  ;; Now create the turtles and have each created turtle call the functions setup-cars and set-car-color
4 {9 Y9 D2 Z8 s% C4 ]" _0 n7 n6 z  crt num-cars. J4 U6 j! Q, g  V
  [
. F3 L. D: h# p  @5 G    setup-cars& ]- k" P8 a4 p/ u" M/ v
    set-car-color( e. ~. A# S2 U# ]: V4 ~
    record-data5 h$ @* i/ H' q/ I
  ]. u$ k( m  ^2 s% K: ^* s& l: q
* A4 T8 R/ R4 ~) ?6 \& o
  ;; give the turtles an initial speed
  K) y# n) B9 W' Q; g. z  ask turtles [ set-car-speed ]
" }# x4 T" n& f, K: h
  W' L; X* l# l! I  reset-ticks
; q- S6 X/ V8 @! f7 P; Qend! y  ^+ j4 D. C! m! t" ?/ m4 V

' @4 h& ^8 g5 e" W$ m. W+ h  U;; Initialize the global variables to appropriate values
% ~4 i( H; a* x- ~to setup-globals
5 E1 Y; _  ?7 a  set current-light nobody ;; just for now, since there are no lights yet
% j, y! O* `  g' ^6 ]  l) ]  set phase 0  y0 [% l4 M/ P
  set num-cars-stopped 0% c, [( I5 T& S
  set grid-x-inc world-width / grid-size-x' m+ ?2 ~+ ?# A3 Q
  set grid-y-inc world-height / grid-size-y
: K( F) Y; N7 H. I  V0 v4 n& S# u7 S( `7 S
  ;; don't make acceleration 0.1 since we could get a rounding error and end up on a patch boundary- @# H( c! l$ v# q. l3 ~; g
  set acceleration 0.099" p. E/ u: R4 q( E% U
end# ?% o! {! j$ }) D
+ ~8 e: E0 `! I0 Y+ J% B' F
;; Make the patches have appropriate colors, set up the roads and intersections agentsets,/ R) V* E+ \& g9 F* c
;; and initialize the traffic lights to one setting2 ^# v, W2 y9 P- M% g
to setup-patches
- k) u$ y& O) I4 _' s& U- x  ;; initialize the patch-owned variables and color the patches to a base-color, U7 o& ^# B; }; V
  ask patches* y5 w" `) f$ @) {0 a( B
  [+ o9 i6 I5 `4 Z3 ?1 f" i
    set intersection? false3 Y& M0 d+ S5 _" W" I+ L/ C
    set auto? false
; H  g% H/ h3 s: d; ]    set green-light-up? true9 `( U( q3 Q: V+ `0 J# P. F
    set my-row -1! f9 S: i7 q; ?" X  n4 @# F& D2 w
    set my-column -15 q) Y) _3 o6 A* S# _( Q2 M5 T% n
    set my-phase -1
( u. R7 q' h  G1 O# P3 {4 _' B    set pcolor brown + 3) M% [$ r& |; `
  ]
* i$ A+ G$ Z$ A; j. J$ z: V
7 u* }6 W8 x8 g1 h' B7 S0 N  ;; initialize the global variables that hold patch agentsets
4 T0 j6 `' K: }2 q$ N* `. g  set roads patches with
; w, Z: w, i; Q5 K- G7 h- O    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) or
, L: [2 g( t( V5 y5 d3 I& \- ^    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]. K  o" H  ?; S9 s# X* G
  set intersections roads with0 N" q& M# z9 I/ f: J
    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) and
5 y* M) ~% @0 x3 g; W) X  T    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]( P# o4 |9 q  l8 Y
, @9 Z; H' K( z$ M2 w2 S* J/ {
  ask roads [ set pcolor white ]
- @3 K& ?/ a1 g" S: @  l8 G    setup-intersections" D) L& D4 `" N; ]/ D
end3 L2 {0 d( i; Q, N; Z6 f/ j
其中定义道路的句子,如下所示,是什么意思啊?* X& Z! x: c6 }; x) N
set roads patches with
, L5 N6 N7 n- _! U    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) or8 r0 d& i* f/ x0 s: A; I
    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]
1 }; r3 _, u1 w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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