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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。9 H6 @: m8 }  a
netlogo自带的social science--traffic grid这一例子当中,1 m# B" p" t9 `4 I/ j$ L
globals; a" W' ]; \1 V
[
0 V2 Z& T; |5 W! k' Z  grid-x-inc               ;; the amount of patches in between two roads in the x direction
0 s0 m! [" v: Y2 B, m6 j  grid-y-inc               ;; the amount of patches in between two roads in the y direction  I6 q5 b6 s  Q
  acceleration             ;; the constant that controls how much a car speeds up or slows down by if
6 h* K9 r5 d( M                           ;; it is to accelerate or decelerate
  ^9 z' E5 W" Q% R" h  phase                    ;; keeps track of the phase$ s$ P0 O! ^/ {5 G; T2 l8 I2 z% ^
  num-cars-stopped         ;; the number of cars that are stopped during a single pass thru the go procedure
- ]7 y& v6 _* B' ^: S' L- Q  current-light            ;; the currently selected light
6 s3 x# o' d3 G% E- m$ I9 i" B( v) S# D; x1 i- e+ |+ ~5 O
  ;; patch agentsets
4 k3 a3 t1 X/ a  intersections ;; agentset containing the patches that are intersections
8 d8 z: V1 f8 I3 k9 p1 T/ D% R0 c  roads         ;; agentset containing the patches that are roads  f) |) h+ x2 D
]4 s* V$ o' [, v

1 M2 n# Q2 ^( U! Fturtles-own6 b+ x. \7 ~* H1 i$ T/ e5 a
[
! F' k3 q- ^. f- n* y% {  speed     ;; the speed of the turtle- z3 P/ Q% [# W6 w
  up-car?   ;; true if the turtle moves downwards and false if it moves to the right
' L% G% T8 G& w8 U  wait-time ;; the amount of time since the last time a turtle has moved' ~% C! q5 b  v; W
]
4 S) [4 P9 F, l
8 v/ Z* r& J. T2 l" u4 t1 Spatches-own/ B" `9 E5 ]2 S
[
& q0 D4 @8 ~* y4 `' F) a  intersection?   ;; true if the patch is at the intersection of two roads) y7 @/ X' C# m+ h. B8 N1 Z& Q& A
  green-light-up? ;; true if the green light is above the intersection.  otherwise, false.
3 B" |. b. D5 t                  ;; false for a non-intersection patches.) i* P: l& G6 o
  my-row          ;; the row of the intersection counting from the upper left corner of the
  n' Q# p, f4 D$ K1 z  K                  ;; world.  -1 for non-intersection patches.
. I1 A3 ~, w0 V3 C& z  L. O+ H7 o  my-column       ;; the column of the intersection counting from the upper left corner of the8 ?$ b8 O( u2 p# R
                  ;; world.  -1 for non-intersection patches." \% L7 N! i$ U
  my-phase        ;; the phase for the intersection.  -1 for non-intersection patches.
$ H1 ?6 D0 [4 Y; B- M  auto?           ;; whether or not this intersection will switch automatically.
8 @+ o1 C5 k) n0 i. ^                  ;; false for non-intersection patches.5 a4 x  }" \4 C& Z& S! O; E  m
]
8 o+ o7 I6 v' d
' [4 ]7 ^( B. i9 x2 v' S1 M, X2 O+ _" c
;;;;;;;;;;;;;;;;;;;;;;
+ R$ A. {  }- m, a& J6 g. n) s. s( e;; Setup Procedures ;;( |6 ]$ Z+ N3 M
;;;;;;;;;;;;;;;;;;;;;;# X" r7 u# E) Q, ^

1 p7 c; L, ~( j8 w+ h;; Initialize the display by giving the global and patch variables initial values.
6 |$ A- G4 \" e' P3 k8 M;; Create num-cars of turtles if there are enough road patches for one turtle to
! `/ K5 ^& t& K3 m" Z, i5 d/ i;; be created per road patch. Set up the plots.
# c: e* C+ l9 N& P; \to setup
! \9 P" E/ M4 y; S2 i  ca
# l9 g7 e2 s+ Y: L  setup-globals
, u; D- F. u& f. e  A# t0 I$ A8 E( u/ v# v6 O0 L
  ;; First we ask the patches to draw themselves and set up a few variables
7 t4 H! Q* ^. m& ?  setup-patches# b9 L( K4 R+ B3 q; W1 N3 j
  make-current one-of intersections( i3 p0 O5 e5 l# I
  label-current
3 e% ?9 Y" r, u+ j  e  o! J- p) H5 p
  set-default-shape turtles "car"3 X# _( r& U8 S/ F0 X7 l$ ]

+ T7 u$ C! i& i  \" X' R* S# g% m% g/ l  if (num-cars > count roads)
# P# |& q4 S! ]" d/ x: {* C: D; l  [
2 k% \4 ~2 G2 Y& r5 R% f8 Q0 r    user-message (word "There are too many cars for the amount of "  S, C; ?& s! C0 Z% [9 b
                       "road.  Either increase the amount of roads "; k+ l7 t5 t2 ^( J1 R0 y
                       "by increasing the GRID-SIZE-X or "
" V) ?* b/ A% P2 s9 x" t5 n) {                       "GRID-SIZE-Y sliders, or decrease the "! u# A) B$ F* }4 l3 h. y
                       "number of cars by lowering the NUMBER slider.\n"
7 }$ |( ]4 a7 q6 w4 g) z7 h$ n1 @                       "The setup has stopped.")& y1 q0 I" G4 S* f7 F$ U. K
    stop
: D( N& F; }( }$ q$ f. {  ]
0 f) d3 M. c3 P& y1 j# z9 U6 B, v9 C3 Q  S) c( v/ V. b1 S
  ;; Now create the turtles and have each created turtle call the functions setup-cars and set-car-color7 q% R+ K. V1 f* B* R' B# v
  crt num-cars3 N! ?7 u% `; p  G# k( a
  [
$ {6 |' K8 a6 _7 K, Q+ }    setup-cars
1 }. b# A" s7 w2 Z. m3 x' ~5 L    set-car-color
/ P8 q( F+ V# l9 v    record-data
2 `. T: e9 b* J( m+ F. D  ]
. u! Y; Q5 r+ y- A* i( E) d% K$ Y/ q1 p" r2 b1 u* b
  ;; give the turtles an initial speed% I4 e9 M1 j  X; B% {
  ask turtles [ set-car-speed ]
3 r+ Q' k/ M* X& [3 A4 K9 x, A
: M8 S# r  O0 o: m  reset-ticks
$ }/ C% l7 O1 U9 V/ f8 J& E2 Gend& [1 n; A3 B* U8 T: w6 X6 v
4 K6 c: R; _4 [+ s& @
;; Initialize the global variables to appropriate values
6 f1 [1 {0 T" s( Uto setup-globals, |/ F" x# s( G8 B7 I/ S
  set current-light nobody ;; just for now, since there are no lights yet8 V, m' l; [! i0 }, a& _" t( E
  set phase 0
7 Z$ I. D$ s5 f" \+ ]% @6 @  set num-cars-stopped 0
4 k+ i5 g5 u3 y7 y# B  set grid-x-inc world-width / grid-size-x
0 \! v. M4 a( _- n  set grid-y-inc world-height / grid-size-y
: r& [& T9 p' `' ^' H- l, z; E$ d' O. x* r; i% F& d$ N
  ;; don't make acceleration 0.1 since we could get a rounding error and end up on a patch boundary
, W( Q# H7 p$ c' n  set acceleration 0.099
4 w' {5 E5 x  ^. u. p+ a$ Oend5 T/ N. _! b2 W/ Q

4 `9 e2 |; w, Y+ M& J( `( A# v;; Make the patches have appropriate colors, set up the roads and intersections agentsets,
# j* @, k' V( E. v) x;; and initialize the traffic lights to one setting
; h5 {+ X" Y5 C. v$ b1 J3 }to setup-patches, ^7 S3 N  Q; g
  ;; initialize the patch-owned variables and color the patches to a base-color% M5 x3 O, T4 x+ b( ^
  ask patches" m/ v  Q  z2 X. c
  [
0 `6 ]* p2 F! j4 ~    set intersection? false$ |+ z" ]5 w% a% k4 F* C6 e/ l. C
    set auto? false+ N1 w) i" `; L( N
    set green-light-up? true
) J) B7 C$ p: Q, t5 X    set my-row -1- z. K1 z% M5 V: a
    set my-column -1+ y% S' n- H# n* c) E& R) D) J
    set my-phase -17 Z$ L3 @0 u3 U  q& u+ U
    set pcolor brown + 3
: ?! ^* D) x+ E- T5 K7 w8 ~  ]0 C/ b7 o) h: ~4 g  j/ f: f* ~1 i0 F
9 o" r% U) v, F
  ;; initialize the global variables that hold patch agentsets% Y! |5 S) O+ r" a, A
  set roads patches with
+ k8 r3 Y" n. T: v& V) a8 x7 ]    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) or
) h! L  o' r$ V1 l, ^2 h( F    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]  u" G' B7 y% G/ Y3 R5 ^+ C" {
  set intersections roads with
, D' N' b& Y8 l+ |! i' `    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) and5 d; h+ T* O5 z, B( E
    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]
8 M9 E* m  E' F+ F; W  u& l4 d; C( z( I) p, w( h% p/ W
  ask roads [ set pcolor white ]
) g, {  O/ t0 c3 C. B: w$ e' ~    setup-intersections7 V3 Z/ `$ ^3 V: `% ^. I, M- \! C- B7 M
end3 g  k! u. ]' \. x$ _6 {
其中定义道路的句子,如下所示,是什么意思啊?0 _- V$ X- R4 R, g- b2 @* A* T
set roads patches with  K+ y% w  Y: S
    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) or
, z7 a! }0 m" E- x: f. k* u4 ~    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]
; v4 N3 Q4 h: ?2 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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