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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。4 Q  x" {- o; {# g3 B
netlogo自带的social science--traffic grid这一例子当中,
8 J" h) K0 h1 n& j+ qglobals
6 B$ d' u( c2 w3 Y9 c6 r  z4 g[
) |+ z; n0 |3 I8 a  grid-x-inc               ;; the amount of patches in between two roads in the x direction
/ d4 Z7 F" y; z( j* H% H, u9 M  grid-y-inc               ;; the amount of patches in between two roads in the y direction
- C4 L# m, L: L' m+ l+ q" N4 C; ?  acceleration             ;; the constant that controls how much a car speeds up or slows down by if7 C! I0 K+ v' e8 j% A1 M
                           ;; it is to accelerate or decelerate
" a( l' X* W; I1 W2 @( c3 c2 ^  phase                    ;; keeps track of the phase9 D% O. J, h3 p+ F! W
  num-cars-stopped         ;; the number of cars that are stopped during a single pass thru the go procedure5 E4 [) \9 B" T( t
  current-light            ;; the currently selected light
9 m. m  ?3 W$ T0 {% @' `" M6 a2 _9 ?/ o" x
  ;; patch agentsets) u" f0 I9 j2 O- s4 t  G
  intersections ;; agentset containing the patches that are intersections4 ]7 E% r+ ~; _7 v# ]5 b
  roads         ;; agentset containing the patches that are roads: h2 e7 ]0 g! @7 o
]
' O$ M6 t+ n. b- Q3 w) ~$ R( h) }: P1 d
turtles-own; U9 R7 G3 @1 Z  [: S3 ]
[* B6 N' s- r9 T! \7 Z0 s
  speed     ;; the speed of the turtle$ ~- G# E! }/ O/ x
  up-car?   ;; true if the turtle moves downwards and false if it moves to the right' Y5 |% Y4 q: Y. l
  wait-time ;; the amount of time since the last time a turtle has moved0 [3 \0 p! ]* A& J& L$ O1 p! |
], U3 i6 ^% |% e1 p

9 x% U! ]/ o7 J" e' G5 Upatches-own
- p; g; T! b/ Q8 }3 R% n/ R% i[
& O# K: G4 m, _$ _/ ]% t  intersection?   ;; true if the patch is at the intersection of two roads3 J! S0 t7 c* e- R' P" e
  green-light-up? ;; true if the green light is above the intersection.  otherwise, false.
9 ?% L7 X: E$ P! ~2 l7 y                  ;; false for a non-intersection patches.
; \9 u* l) ], u% \% `. @; a- K" V  my-row          ;; the row of the intersection counting from the upper left corner of the, H+ O- _6 f4 W  u; w# u0 ]$ S
                  ;; world.  -1 for non-intersection patches.
5 h  s/ J& b$ U; D) U  my-column       ;; the column of the intersection counting from the upper left corner of the2 l9 c" r2 e0 Q; {
                  ;; world.  -1 for non-intersection patches.
9 |  m6 V5 E0 Q* B7 y' `1 T  my-phase        ;; the phase for the intersection.  -1 for non-intersection patches.4 z" c. s" }/ p
  auto?           ;; whether or not this intersection will switch automatically.
/ N0 V( h0 ~) Y9 b  d9 v                  ;; false for non-intersection patches.
1 f+ @& g# t5 Q+ v1 q) Y2 C]
8 y$ t1 I; P& W7 w2 C
' T! M; ~2 U% ^/ j% e
& m% K, p! d  P: {' h" S6 x9 V+ p;;;;;;;;;;;;;;;;;;;;;;
1 @$ D3 U: ^( f) ?/ x0 V;; Setup Procedures ;;1 b. z6 K& Q: G! R8 C4 @/ _6 _2 n
;;;;;;;;;;;;;;;;;;;;;;
) p2 T% v' x: u, {0 ^6 D0 e1 c: L' n# o1 d/ {4 f' y1 {5 Z
;; Initialize the display by giving the global and patch variables initial values.
! t3 b, H- {6 m; X;; Create num-cars of turtles if there are enough road patches for one turtle to( t  m) m+ d2 x. x8 Q, K
;; be created per road patch. Set up the plots.
) @9 w+ z8 N. ~0 Mto setup
* S& H9 I1 z8 T/ H  ca
' `) I2 X- Y/ V2 B  setup-globals& h/ R' R+ [' Z& R) v+ q
; T9 m- o& l) S6 b2 l* ?  ~
  ;; First we ask the patches to draw themselves and set up a few variables
3 U  r% w9 H0 V) K  setup-patches; b1 n. ~- U* R* h1 i
  make-current one-of intersections# w1 E3 T# N0 H$ \) C
  label-current( [0 p) r& B4 x- W2 R1 f9 N, m' R
5 M$ |: x+ ]! d! B: x: w6 s% [2 b7 R
  set-default-shape turtles "car"4 a& G6 P1 k5 p! t* y
, J! W/ j- E7 z2 [) J$ T
  if (num-cars > count roads)' t6 z7 _' y8 ?1 }& X
  [
* p) D+ {& B/ Y. U' _1 v2 n    user-message (word "There are too many cars for the amount of "
+ c2 l1 c5 M1 x& X6 J2 o: |7 h9 N                       "road.  Either increase the amount of roads "
$ a* v, k; T, B6 d. V. K3 s, b/ _1 Z8 C                       "by increasing the GRID-SIZE-X or "5 i+ Y7 u% K. q" K; G9 u
                       "GRID-SIZE-Y sliders, or decrease the "
1 f4 u4 J% \, B7 s" y& f2 T                       "number of cars by lowering the NUMBER slider.\n"8 E7 Q9 \( _0 N) R: U
                       "The setup has stopped.")
: i" o( ], F; j* ?& Y8 J/ }    stop& e+ ?& Q/ Y) ?+ i
  ]
$ h/ j2 \* c/ ?& L7 R
; Y4 C7 a: c2 Y  ;; Now create the turtles and have each created turtle call the functions setup-cars and set-car-color
# X3 |6 i. @/ \' T2 K# ]$ n  crt num-cars/ X( F/ D+ W" i" |
  [
4 _1 `' q' m9 L0 P+ A3 \) o$ `    setup-cars
) z4 r  y7 _% S1 ]. |0 I# X5 v    set-car-color) u/ y; ~, @: {( F0 ]( \
    record-data6 V6 P5 S. O) t# S5 D/ m: h! }
  ]0 z1 r" y- ~& q& `3 Z' V
. \" o9 j. z2 n/ }0 Y1 _% l
  ;; give the turtles an initial speed, L: H0 m" M! a* j9 L9 L
  ask turtles [ set-car-speed ]
! b% L7 Q6 f( M+ T. p* T# C% ]: a9 @5 F$ t1 L; I" g/ B* n
  reset-ticks
8 \/ L1 K8 o0 Q4 Fend1 v. L1 Z0 O8 c% D+ J
8 D0 u9 P5 p: C7 y# E7 t
;; Initialize the global variables to appropriate values
$ U, H' x# U2 w" |0 ]. U: e4 Kto setup-globals$ p2 a$ C# {% q/ t9 z( e1 n# F
  set current-light nobody ;; just for now, since there are no lights yet
1 X6 w2 Y, N" Q: n  set phase 0  v! v( f2 h2 a) n1 g" S, y# y
  set num-cars-stopped 0
9 l  H) n7 s* ~+ b/ w9 ?  set grid-x-inc world-width / grid-size-x
% K1 F6 |7 w+ p- w  set grid-y-inc world-height / grid-size-y
& X, G# J/ V$ E* X' ^& N
' E: r5 _, N$ l7 K  ;; don't make acceleration 0.1 since we could get a rounding error and end up on a patch boundary% G# b2 a3 u9 Y5 q  {
  set acceleration 0.099
! V3 F' c* ~: {- P3 J7 Oend
/ |/ V$ L6 R8 B  ~' S1 D) h7 ^" m4 ]5 o
;; Make the patches have appropriate colors, set up the roads and intersections agentsets,
4 D( H9 C& j% r: S( `) M;; and initialize the traffic lights to one setting
. {! H& ]# S( M! ]  i3 f& K2 J' H4 |to setup-patches( o4 ~+ N& @* V$ g! j
  ;; initialize the patch-owned variables and color the patches to a base-color" w' d& e. Z$ u9 F  f0 z8 \6 h
  ask patches9 x9 f4 k% f% @' E
  [" l. e& D5 ?$ u7 p" _3 G6 V
    set intersection? false
  B& A, M! g: X: w: ^0 V+ B    set auto? false
$ h2 r/ O5 L9 k* s    set green-light-up? true* Q2 b1 N- L( ?& }+ G. ]
    set my-row -1; Z; f. {" {% r4 {" W
    set my-column -10 L2 C' y3 W; |+ `; X6 R
    set my-phase -18 `# A6 }$ U" i: o# k) K6 G2 ?
    set pcolor brown + 3
; A- J/ c6 P0 v( I( T  ]' r  V2 O' s0 A4 p& o! G' p
. Q( E: H7 u( {* G3 ?
  ;; initialize the global variables that hold patch agentsets
' _/ w9 \: r8 R) u  set roads patches with
' {* X3 H6 d( \$ d' r    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) or% {2 d& V. y5 l7 {; d1 ^
    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]
2 F$ @1 C& s" h3 l; z2 W- a  set intersections roads with4 z$ }: R0 }$ T  O8 m' }
    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) and
5 A* {4 b1 A( a    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]) F4 E5 c) I' K7 T2 Q" O. K( M
4 [1 Z5 J- I& s. A) O9 |
  ask roads [ set pcolor white ]
2 b8 S3 `5 c6 s    setup-intersections6 I7 N- a) i4 |- D) ~6 g
end
5 I, @$ c+ O0 q其中定义道路的句子,如下所示,是什么意思啊?# L4 F8 e# ^! t* B
set roads patches with
5 O2 \/ D5 _: A+ H1 h    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) or# w! s5 C' d0 o, Q0 _) v: j
    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]
; ^& |3 O! T% C& y+ C- O: 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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