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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。
- j+ K( Z* q# ^. _6 Bnetlogo自带的social science--traffic grid这一例子当中,
5 A: Y% y' \& {) g$ k6 zglobals0 D- A4 x6 X  T  L( }
[
. a* V6 u4 m" w1 s% A1 k  grid-x-inc               ;; the amount of patches in between two roads in the x direction9 L, B7 @* h6 ~( }; E, M( z
  grid-y-inc               ;; the amount of patches in between two roads in the y direction6 B+ F5 ^* X0 n7 `
  acceleration             ;; the constant that controls how much a car speeds up or slows down by if
/ `$ P) D$ M: z/ P+ T                           ;; it is to accelerate or decelerate
- U( k/ H9 f3 A- U0 }9 m1 H  phase                    ;; keeps track of the phase, ]3 e  ^$ z# v) E2 |7 y
  num-cars-stopped         ;; the number of cars that are stopped during a single pass thru the go procedure/ n+ Y5 r; D! h% h! F6 F4 ?
  current-light            ;; the currently selected light6 B8 U# F9 f3 [, P$ Q
; G4 ~( k& a; s) z
  ;; patch agentsets7 S* A; S5 ~7 l
  intersections ;; agentset containing the patches that are intersections& t6 J$ I4 a. D; Z% P4 t4 r7 i
  roads         ;; agentset containing the patches that are roads
+ U# `& D/ L+ T( C) b]
! T( R; Z% E) P. L: v% i! b' x% w0 N
, X7 z/ o: C4 Z  Wturtles-own
: `( j( A* U7 C8 |( y[2 U0 a7 A/ t! k8 g. m
  speed     ;; the speed of the turtle% F/ M5 j" j2 N3 G4 A2 D; s1 h
  up-car?   ;; true if the turtle moves downwards and false if it moves to the right4 S9 ^% F! ^" w. j& i3 z
  wait-time ;; the amount of time since the last time a turtle has moved3 B2 I% B# \/ l1 k! f; P' ?
]
1 i/ w) _0 O+ U$ P4 _' O, Z6 `9 _2 `: y/ j& y
patches-own( N: }6 Y5 g, _* T
[
; P# A4 ^" u1 t9 }1 ^4 ]( L  intersection?   ;; true if the patch is at the intersection of two roads
5 f& k+ m0 X4 e" ?; F+ K6 y  green-light-up? ;; true if the green light is above the intersection.  otherwise, false.- d0 r0 v( @, t* c8 Z
                  ;; false for a non-intersection patches.
' p% j, F5 Y: A; R  my-row          ;; the row of the intersection counting from the upper left corner of the
" g1 b# e; W+ U& q+ z& c9 `                  ;; world.  -1 for non-intersection patches.5 y3 ?+ _6 r) H0 j7 O  f1 s
  my-column       ;; the column of the intersection counting from the upper left corner of the) O4 q/ X- t+ |2 g8 E- V
                  ;; world.  -1 for non-intersection patches.
& p, ?/ b! r; E2 d2 ~' M1 r$ K  my-phase        ;; the phase for the intersection.  -1 for non-intersection patches.0 C) n* F/ Z- x! j1 K; p9 z
  auto?           ;; whether or not this intersection will switch automatically.& N3 {. d) r+ J7 t
                  ;; false for non-intersection patches.
3 \% s  L) V& x, G. G+ \6 C]+ ~" T8 g$ Q& D* g1 w9 `4 {

- t6 B9 d0 o: c* u0 e$ v8 B5 |* b5 D2 U8 N% ?
;;;;;;;;;;;;;;;;;;;;;;# }. W' n* {7 V* E/ m8 q$ M
;; Setup Procedures ;;
$ E1 d7 `- y6 [' v8 O;;;;;;;;;;;;;;;;;;;;;;3 r8 s4 `) H8 t0 F+ `; J

9 u. ?* [1 u  i: R# ^/ x;; Initialize the display by giving the global and patch variables initial values., `7 ~- |& \# x3 r5 z+ u
;; Create num-cars of turtles if there are enough road patches for one turtle to+ O& J& H* k7 p4 `" n6 `  }  F" G
;; be created per road patch. Set up the plots.$ b4 p, ~4 H( t0 q5 |1 @' p
to setup6 c7 @6 t& @6 t$ F/ b
  ca
4 \0 ~1 n( c* u: p  setup-globals8 q; k7 y; j# p5 k; h
, n0 T* d, D. P# j. L
  ;; First we ask the patches to draw themselves and set up a few variables
  N+ H' Z% ~# K+ \# c  setup-patches- H! n% B) M- T1 [/ {. F7 T9 |% a0 d
  make-current one-of intersections. B$ g) ?& _7 W3 K/ K
  label-current
" G7 u0 a2 N# c) c' k3 [, l' q" U9 `
  set-default-shape turtles "car"* s" y6 t& y9 q& ?$ m
# w0 T* o2 o% f: l, r& t
  if (num-cars > count roads)
. x2 x/ ~' @' d4 l  [; ]+ m; b7 ~5 a1 Q; k, z# o
    user-message (word "There are too many cars for the amount of "
, E4 t) v& t% g3 p/ @% w; U                       "road.  Either increase the amount of roads "
2 u8 _% F5 @% K: e1 P0 b. y1 F                       "by increasing the GRID-SIZE-X or "$ b: I# o& O) G' n$ t
                       "GRID-SIZE-Y sliders, or decrease the "
; Q- m$ A4 n. X, Z                       "number of cars by lowering the NUMBER slider.\n"
' i. o$ W' E9 i9 K  x                       "The setup has stopped.")4 |: |& B: u8 L% l9 [
    stop
: {! x6 }' S8 Y! j+ l  ^& V  ]: Q' V4 g4 ~; k9 e$ X2 p
0 C, f; Q; [' F9 J0 j, F" H
  ;; Now create the turtles and have each created turtle call the functions setup-cars and set-car-color7 o4 D! H. O3 D
  crt num-cars$ }0 R( _$ N3 N, O4 `! s6 X
  [2 r( V# q3 o/ E2 P' @3 E
    setup-cars
/ I  ^$ d5 w6 n& F    set-car-color
4 n! o* X: h' n+ c  y- d8 c    record-data
  M2 W4 h& p) v8 U3 t5 M  ]
0 g% p) A: H; Z! B8 r
% E* h1 S1 f1 b# Y" ]3 Y  ;; give the turtles an initial speed# G! T7 i( g/ h9 A  R' E! J5 j8 S7 `
  ask turtles [ set-car-speed ]
2 m8 r, f1 N; F) h( D" V- W/ o* D+ |: K6 e* x' c, Q) \2 w
  reset-ticks
! b5 M  e/ t* S3 M" tend( c, I" h) {' x7 R* L
  T& v; R7 e- C1 Z* ~
;; Initialize the global variables to appropriate values9 A5 h1 H; ]: B, i% {6 k) H
to setup-globals$ h+ Q8 `# S* d+ w/ ?5 e
  set current-light nobody ;; just for now, since there are no lights yet
/ U& s9 i. |( p/ r. L  set phase 02 t+ X7 R: w# B, W
  set num-cars-stopped 0
1 a: \! M! g+ O- e. p  set grid-x-inc world-width / grid-size-x. m3 j) k1 Z+ N, O
  set grid-y-inc world-height / grid-size-y% z& J* {) y, g) \6 ]
0 q" U$ x! d" K3 |6 ]
  ;; don't make acceleration 0.1 since we could get a rounding error and end up on a patch boundary
6 O/ w3 W( {& E. R  set acceleration 0.099
) r( K5 n4 J" M: ^1 Hend
( g, b5 r7 f3 J0 h# b) E' @6 N0 q$ D9 z( A5 T, j6 e7 O/ K( ^- E
;; Make the patches have appropriate colors, set up the roads and intersections agentsets,8 V  P% d) v; |. b
;; and initialize the traffic lights to one setting3 l6 K# J8 K2 L3 X. h
to setup-patches
# j; c1 Z6 \: q, ?+ ^3 ~2 }  ;; initialize the patch-owned variables and color the patches to a base-color3 g  E) T: U5 U' X' S* a
  ask patches% {  p& @% m& ]2 @4 S( g
  [
4 ?( U( B# h$ a    set intersection? false; X0 L5 K, b$ o
    set auto? false0 D5 v7 j9 Z9 {# \6 j1 g
    set green-light-up? true
9 U' }* L0 W( j- {    set my-row -10 z! P3 `% Y# E! m+ N2 D1 s, N
    set my-column -1
  t+ V# x; M7 v6 u. G, S    set my-phase -1/ Q4 G% S3 q  c, e$ H5 ]7 r
    set pcolor brown + 3
+ ]- w) S8 F/ _) K- G; f* Y9 P/ `  ]1 k( O% {4 S" L9 T

- T% z: `) W( {2 N( D9 k  ;; initialize the global variables that hold patch agentsets' a/ M: e( K3 S4 p9 X
  set roads patches with
" R5 k4 A: |: }' T& s    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) or5 @4 H8 g* p/ k4 G3 u. e
    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]
2 b# t: m& k, O2 @9 v1 w6 F  set intersections roads with
3 D2 k( o& q  g  t( W  h    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) and- F+ E2 s3 Y) X/ }3 a" z5 X
    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]& y8 g4 f3 k7 ?) `" \1 b( N

2 _' c2 p, N& \6 B$ U! W% X) j  ask roads [ set pcolor white ]
: N9 q, J- l  C4 x( }- S    setup-intersections. ~" G1 w1 Z& |( \8 }2 w
end
8 _! i/ f8 R! h" x* K( C* o, \其中定义道路的句子,如下所示,是什么意思啊?7 X2 w+ P( ?0 B5 Z. J
set roads patches with0 y. l! ?3 g) [! [
    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) or4 e0 ]2 N4 ~) `0 S
    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]& E, d1 [1 B# b2 a
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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