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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。  s. J4 |0 q$ R# o0 e0 q5 {
netlogo自带的social science--traffic grid这一例子当中,
( K4 a* L8 @! Zglobals
8 G* r& W) P- O! |% }# W/ i4 J[
# Y4 ~- Z9 M1 d, e' M: x  grid-x-inc               ;; the amount of patches in between two roads in the x direction
# L1 P  s$ l7 B! N5 l3 n9 g  grid-y-inc               ;; the amount of patches in between two roads in the y direction
7 k- z1 P; u2 w" v: ?  acceleration             ;; the constant that controls how much a car speeds up or slows down by if
7 |( |- \. D0 k& y                           ;; it is to accelerate or decelerate" C' z8 h! b/ n1 h" Q1 s" {
  phase                    ;; keeps track of the phase
" K) g6 o+ i6 O% x# R6 l  num-cars-stopped         ;; the number of cars that are stopped during a single pass thru the go procedure# \6 w# x# i6 r* F' Z- x
  current-light            ;; the currently selected light
; A/ q# b2 g) N% |: N/ |3 v6 d; [
  ;; patch agentsets/ H& j- [0 B+ G4 Z5 n- Q% h
  intersections ;; agentset containing the patches that are intersections
" M) z! A& m- @6 T  roads         ;; agentset containing the patches that are roads
7 g$ ?1 w0 a# E- g/ w]1 z8 g( m8 r9 o4 j

8 }6 L& f* n1 iturtles-own( F8 J! \1 X% M9 N* ~
[2 @0 f8 m. Y. n; ~
  speed     ;; the speed of the turtle
5 b$ P: F) o) h+ N& j# z  up-car?   ;; true if the turtle moves downwards and false if it moves to the right3 \4 D( ^/ H: h& H3 O: z9 z: N5 N0 f
  wait-time ;; the amount of time since the last time a turtle has moved  t) @7 l* B$ [( x( b
]2 t: U) k6 L4 l  _0 d6 S8 i, F

* ^+ r( z' I+ i1 g6 X( z( spatches-own
; H: E* f; m2 ]1 B3 n; u( N) x[  ]# }0 ^( I: k6 a
  intersection?   ;; true if the patch is at the intersection of two roads
( W% j, x* ~& ?  green-light-up? ;; true if the green light is above the intersection.  otherwise, false.
$ s6 M) e! Q: R                  ;; false for a non-intersection patches.
" e) b9 E# [) q  my-row          ;; the row of the intersection counting from the upper left corner of the
5 `- ?* X" ~$ @3 V: d( H7 Z0 U                  ;; world.  -1 for non-intersection patches.
: b8 S4 [5 S: ^* M6 W1 Y8 ]  my-column       ;; the column of the intersection counting from the upper left corner of the3 E! ]* I1 m6 r( e5 \( B
                  ;; world.  -1 for non-intersection patches.9 f0 X* I- o" y
  my-phase        ;; the phase for the intersection.  -1 for non-intersection patches.
5 P$ k4 V4 m1 m0 m, B! r  auto?           ;; whether or not this intersection will switch automatically.( [7 y; E/ R6 W8 X; {+ `4 ?
                  ;; false for non-intersection patches.# p. g' M4 l$ w5 B2 W2 L; a6 f
]% l4 N3 {" x& x- x9 B

4 N5 X1 n% c, r# n1 C
/ H* y8 Y# S* t2 l;;;;;;;;;;;;;;;;;;;;;;0 k  W- U5 [6 h. p; T4 {
;; Setup Procedures ;;
: N! L3 N% P' ^  x& F) g& t4 Q0 s4 P;;;;;;;;;;;;;;;;;;;;;;3 h& B% ^$ A; w4 Y0 E# j: b  C

1 v( K6 Q3 h" X6 h' j1 ~( N;; Initialize the display by giving the global and patch variables initial values.1 ~& g$ e8 }: z/ R1 l) j  P
;; Create num-cars of turtles if there are enough road patches for one turtle to
5 d3 o" w3 j4 A$ S1 K3 I7 y- N;; be created per road patch. Set up the plots." p6 d& l  R' }3 Y7 _' ~, ?8 N! K
to setup
9 r& X. W% _( O  ca; w# T7 X+ [( P' ]
  setup-globals
$ V- W3 B, U, ~" d
" M$ v! M4 ?9 r4 G3 L6 X; s( n4 o  ;; First we ask the patches to draw themselves and set up a few variables5 G7 I, Q: J+ R$ f* h* k4 c. U
  setup-patches: j" \( s7 V5 c8 H, V
  make-current one-of intersections' |6 u# E+ }6 r4 b0 f/ H& r: w. x! ~9 Q
  label-current. e4 O' a' [& D* H2 D0 f/ N3 n
( E3 W! g6 A, a' B1 U6 T. b
  set-default-shape turtles "car"' l8 E6 N& T/ B" I. P0 ?6 b

+ ^7 ~# O2 f; N6 i& x; A5 H5 o  if (num-cars > count roads)% t- |! D9 U* Y3 G; t
  [; t( k% o; B; B! [0 Y" Z, D% V2 m
    user-message (word "There are too many cars for the amount of "
: Y0 i4 e4 e2 N                       "road.  Either increase the amount of roads "' s/ X: s0 O: W0 R9 Q
                       "by increasing the GRID-SIZE-X or "
7 p- U4 G3 o$ e                       "GRID-SIZE-Y sliders, or decrease the ". m) W; t8 u& {
                       "number of cars by lowering the NUMBER slider.\n"
* ?% a" f9 g/ X% k, @                       "The setup has stopped.")
% k, u& v" V) z9 u/ A    stop0 |* _5 t  \! y$ ]) A: n7 a
  ]
; C1 X/ I9 b! |( \
1 Q8 L% x4 O& _  ;; Now create the turtles and have each created turtle call the functions setup-cars and set-car-color/ X* W9 {9 W$ B+ O
  crt num-cars; E2 h3 ]4 Q0 L: ?& t6 K
  [; P0 S3 T9 C5 a( P
    setup-cars
* e0 G' o0 o( h' _3 w1 Z/ q    set-car-color7 c3 }1 V2 D) {5 M9 e
    record-data# g) n* Z1 H- Z' f$ A( E( A) {% b
  ]
0 v" @" H3 s& K' q$ ~) M  j3 H; N, @3 @7 M3 n* m0 Y7 e# H  W
  ;; give the turtles an initial speed% |" w* u+ s7 F& S, X+ E
  ask turtles [ set-car-speed ]
  H; d$ J) ]) u7 z! l; s1 Z  `5 u7 U! I7 V9 X
  reset-ticks, A! c6 l0 m3 M& H
end
8 H; W+ H% `6 E
4 E1 K3 Q* C) m. L' w7 x% };; Initialize the global variables to appropriate values: t* k* Z1 J  J. C) u
to setup-globals, b; N1 u3 b$ ?' v$ K9 {& @
  set current-light nobody ;; just for now, since there are no lights yet
/ n6 t9 i# N/ I4 O1 X# D  set phase 0
8 H& ?  O$ F$ b( i0 h" g) e  set num-cars-stopped 0
, C* {$ |& n$ l% b5 @  set grid-x-inc world-width / grid-size-x" b+ }% [6 }# i2 t
  set grid-y-inc world-height / grid-size-y
3 j  d' X  [- ^4 S$ [. j1 i' Y* ]" H/ W- G; s9 `' z
  ;; don't make acceleration 0.1 since we could get a rounding error and end up on a patch boundary
: b* T# [! K+ G3 g# R1 p  set acceleration 0.099' B. s4 ?& X+ l. p; A1 I$ e! ~
end' T+ p8 c5 b1 I  q; |+ K* c3 y

: a. }$ ^2 U. V: \+ W& l  T;; Make the patches have appropriate colors, set up the roads and intersections agentsets,' B& b$ [2 E! n
;; and initialize the traffic lights to one setting7 q) Z1 z6 J5 Z- Z* k- B
to setup-patches
/ B; L# i, y% u, j5 @7 G, g& x+ H  ;; initialize the patch-owned variables and color the patches to a base-color4 k) F% u2 X$ d
  ask patches
# G, E6 a' ^+ J, f1 r  [
6 q3 q' e' j5 f, q( F    set intersection? false
/ s$ q' J0 E6 t. k    set auto? false* t1 W  l1 `6 X% l4 `  Y/ W
    set green-light-up? true) s5 p$ U+ P* r) W1 z0 Q, t$ k
    set my-row -15 c0 _) c) f6 a; y: Z
    set my-column -1
  z( _3 n# H; o    set my-phase -1
+ I- i& s! Z4 B+ b9 x    set pcolor brown + 3
9 c6 ?. e8 A7 g  ]
  g0 B! f; {8 T2 g' |' i# _4 b1 H
+ |1 Y7 w; V1 u/ c) Q, B  ;; initialize the global variables that hold patch agentsets0 [( M* R: C* M/ L; z- @1 R4 T
  set roads patches with2 [; g( V% P/ K+ ^+ G
    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) or) x; }6 ~! C: z$ @  Y
    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]6 e. U% j' u, ~& G3 R
  set intersections roads with* o" d) o4 h8 ]. |1 x) J& k5 M& [+ a
    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) and- ?: x3 Q; ?9 v; J2 A' x& U  Q# ~
    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]
2 Z2 u5 F$ u! W' `
/ e' W& e! E# A2 Q4 t- ?; M& @  ask roads [ set pcolor white ]' |2 Z4 b9 R+ z: @9 F
    setup-intersections2 }& G4 |/ F6 A% B* R3 i$ @
end
' K& N- t) V( @2 D其中定义道路的句子,如下所示,是什么意思啊?0 c) w. c$ }4 {1 u5 C' h% M+ V/ N
set roads patches with8 a: r/ `7 W5 d
    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) or7 ]$ v+ `2 M7 d; y, t9 a; V) O
    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]
# R2 \2 ^  S7 V# M% C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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