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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。
2 i$ y  t# B& {6 n  y" D2 y, q) inetlogo自带的social science--traffic grid这一例子当中,  E! Z% S7 ~3 ]* E- h4 a
globals
4 R" p4 K0 N2 C1 L6 u- U[9 Q  r1 ~6 |( [% F/ d
  grid-x-inc               ;; the amount of patches in between two roads in the x direction! n# m6 u" C' W" N% N' N; G
  grid-y-inc               ;; the amount of patches in between two roads in the y direction* I6 K2 ^/ F; y, x* {
  acceleration             ;; the constant that controls how much a car speeds up or slows down by if$ K; H( C' b3 T( s, r
                           ;; it is to accelerate or decelerate) V: ?4 M% b. q" `( o* ~* [# t' Q
  phase                    ;; keeps track of the phase2 U! v1 l5 ?/ `2 p
  num-cars-stopped         ;; the number of cars that are stopped during a single pass thru the go procedure
$ R& I# K3 N0 q6 N2 v: l- O  current-light            ;; the currently selected light7 N) e9 N1 w0 h2 O

) k( d8 B) {+ D( A9 a- x  K1 a  ;; patch agentsets
2 b) m3 ~. z- H& y. ?0 \9 y  intersections ;; agentset containing the patches that are intersections# T* U/ G0 x/ Q5 v8 i- F$ t) f
  roads         ;; agentset containing the patches that are roads
0 x, {) b+ D6 ^6 j" c( l1 J- g2 a+ t]) U. @2 P! v2 W

: b: Z% S1 R7 Y; o' k& b) Pturtles-own
( ^1 K2 z, H1 _[
7 x0 w4 u- X# F  speed     ;; the speed of the turtle
6 }0 N: m+ G$ D1 n7 F  up-car?   ;; true if the turtle moves downwards and false if it moves to the right. `+ \: c5 N9 F3 s
  wait-time ;; the amount of time since the last time a turtle has moved
( B5 n4 x! \/ P]9 m$ @: y2 o  P9 w9 p8 S5 T
6 H% a# h* J% Z* l8 Z
patches-own- G6 E  ~7 W0 }+ E- ^
[; ^! s9 c6 u+ f3 j! e
  intersection?   ;; true if the patch is at the intersection of two roads* X. I0 \  U; C( N
  green-light-up? ;; true if the green light is above the intersection.  otherwise, false.
1 R4 u% d6 ^& i( C( n! g; X: C# c" |                  ;; false for a non-intersection patches.
5 u. Q. V& N/ C3 e1 F  my-row          ;; the row of the intersection counting from the upper left corner of the
4 {) v0 b8 Z7 j7 p" j( t. }" l                  ;; world.  -1 for non-intersection patches.
  ^3 U( m! y% C& p  my-column       ;; the column of the intersection counting from the upper left corner of the$ p' V. I0 G% l7 v3 ?
                  ;; world.  -1 for non-intersection patches.
$ \" I  D% @, Z! j! b5 c! h  my-phase        ;; the phase for the intersection.  -1 for non-intersection patches.$ S) e$ D1 h+ v' m' ~5 ^, K
  auto?           ;; whether or not this intersection will switch automatically.( T* Q' {. R4 {/ k
                  ;; false for non-intersection patches.( W" u' q: Z- C' l) E3 S
]  v. ~& T$ _1 g; h( j
* X7 {' t1 O7 U6 Y5 D$ N( ^
* w& Q  Z: `% S$ ]# h
;;;;;;;;;;;;;;;;;;;;;;# F' M& t: L4 d1 S' R
;; Setup Procedures ;;
8 R/ M9 ~! D8 X. l. \;;;;;;;;;;;;;;;;;;;;;;
: C! c* G+ P: z+ N
9 f& a6 q) P. H. j& ^& V. s* @' x; s! V;; Initialize the display by giving the global and patch variables initial values.! d7 S) ^, \* j7 V) V
;; Create num-cars of turtles if there are enough road patches for one turtle to% U% @& O# L/ P* P7 C# H
;; be created per road patch. Set up the plots., E4 l; T7 v6 \' t" d
to setup% B, z$ D% _5 [  A% i
  ca
+ Q/ E9 {, o8 V  setup-globals+ M9 p0 C" N& Q) U
: K; a' F# w/ g* H
  ;; First we ask the patches to draw themselves and set up a few variables
# e1 V; x  d, G) Z8 Z/ i. n2 O5 X  `  setup-patches
! o1 k1 c' f2 ~% `  make-current one-of intersections
9 S3 E3 k6 Z' q, B  label-current. z0 U; _& E5 {2 l+ z5 r

0 n/ K5 }6 i# b; L  set-default-shape turtles "car"0 w! b0 u' }2 ?% [

, [! j0 ], y! C0 }9 t7 @  if (num-cars > count roads)* g: o2 \8 `' l3 J4 }0 ]
  [' Z' y+ r; y$ h; e
    user-message (word "There are too many cars for the amount of "
' C  |5 F4 Q7 r                       "road.  Either increase the amount of roads "
, K/ Z/ Y+ ]$ K* s                       "by increasing the GRID-SIZE-X or "
  }- n* K! T( M3 f                       "GRID-SIZE-Y sliders, or decrease the "
8 M" v$ B& [0 q3 B/ P6 n6 Q0 Q' G                       "number of cars by lowering the NUMBER slider.\n"
0 n, k/ J* S+ t& t$ w9 a* N) D8 @                       "The setup has stopped.")
/ u  A2 n- s4 o+ _  f    stop$ z7 D! L( N8 k8 U/ U
  ]3 k( {! ^2 T% V' E

. F) W0 ~1 f) K' [; L  ;; Now create the turtles and have each created turtle call the functions setup-cars and set-car-color& j# t" I" r7 M- o
  crt num-cars' c0 E) O3 |1 v2 y
  [4 m1 A8 ~- I- X, J" i8 |& b
    setup-cars8 B1 \. i9 j) F6 ]8 ^5 ?
    set-car-color! {  ?$ k6 j4 \) j, o- a- v. G
    record-data
+ t9 @3 M; ?5 u  ]
5 k, K! c7 l1 C+ r; a# z
! H- K* x% F8 r7 q8 t( \: p6 N  ;; give the turtles an initial speed
. {; J3 ~0 O/ U; f) J1 S  ask turtles [ set-car-speed ]. c: i& K9 d5 `- V4 I2 O+ ^, i' }5 E
! U  w2 B* J7 V" z3 ^9 }
  reset-ticks
  W3 ]) K! z/ wend( ^" `) b: B$ `

9 _8 k: l% ]8 y) J# Q;; Initialize the global variables to appropriate values
" z7 w. q5 M+ _0 x6 ?. [3 c! Y" yto setup-globals
: l& n, s# z4 T! B! T  set current-light nobody ;; just for now, since there are no lights yet
9 T3 X6 C: P6 y7 E3 _$ k  set phase 0
; w* A' e. A3 K) H$ n  set num-cars-stopped 03 x- [; g5 f. J/ q
  set grid-x-inc world-width / grid-size-x' E( ]$ Y! a6 B- B! J* e0 J  J
  set grid-y-inc world-height / grid-size-y! J$ ^* n( P% s

8 l7 D  e$ O. }1 Z$ K  ;; don't make acceleration 0.1 since we could get a rounding error and end up on a patch boundary/ j) f# R) k7 b3 U/ k' z3 d- w
  set acceleration 0.099- ~4 G- J4 K% ~4 \! F) f
end
, e& T* }# ^9 l! D4 P# v) W6 R& K+ k* X# a1 j  o4 q
;; Make the patches have appropriate colors, set up the roads and intersections agentsets,  y* n. t# K! U1 e
;; and initialize the traffic lights to one setting
& y% v3 W" ?3 g2 P  Fto setup-patches
4 U) G' D$ Q9 a  ;; initialize the patch-owned variables and color the patches to a base-color; q. s. u; F/ r# k6 T8 w
  ask patches$ T+ }& @+ A: m) ^
  [' w% \" r  J" }# T/ M% O
    set intersection? false6 {& H" W% h  j+ \. J( P" \  V# A
    set auto? false1 `* j0 z3 Q8 g% U6 M
    set green-light-up? true
" @2 g+ Z2 j+ `1 ~2 L+ B6 C- _# q    set my-row -1( Q' i, ]9 w8 M( E7 d8 V
    set my-column -1. G0 T) ?2 f7 M& C, m
    set my-phase -1
7 A/ h+ F% k$ E) S9 @! I    set pcolor brown + 3
0 X) e" g+ [+ D7 K" q+ w! C  ]
! r& ]/ o! r0 j% F! D& }$ R( n" E" D1 Z
2 ^2 M3 j8 R6 M7 k3 }7 F3 O4 ^" C  ;; initialize the global variables that hold patch agentsets
9 L8 g7 j  `& ~& ~0 @  set roads patches with
" v! o3 i1 D; R1 Z6 Q# ^% G  n  u    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) or
0 D3 N" @4 d' I: ^    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]
* u: S0 K$ {# E3 K  T% X& Z, I$ {  set intersections roads with
. @) ?0 l; B$ L5 q+ i    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) and
+ ^6 s5 k2 Q; J# V' v6 \    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]7 l; g. ^" G9 L% l1 g: Q' R

& ?" ^& w) t# t  ask roads [ set pcolor white ]' v, @& _: V9 u! L6 X$ q8 m, z
    setup-intersections3 y- d" k) H! k- q9 \, w" F
end- B& n; ~1 y0 ]' i7 L- \+ i8 E3 b" N
其中定义道路的句子,如下所示,是什么意思啊?% j3 r! T/ m" N, s( y
set roads patches with
! ]6 k5 X' j5 B6 ?  ?. `. o: p" `. ]    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) or7 u, v# c+ X9 L- ~9 }
    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]
% z- q+ W/ C2 Z  \, E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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