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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。# l! ^# c' w+ \
netlogo自带的social science--traffic grid这一例子当中,
1 Y' X/ w+ D" ?+ Q) l5 g8 j/ Mglobals. n4 @1 V, G( `! J
[
" I+ e' ?+ i' J. B5 |  grid-x-inc               ;; the amount of patches in between two roads in the x direction
: [: P( ~; b4 x  grid-y-inc               ;; the amount of patches in between two roads in the y direction
5 `. \/ c% N0 f8 v( K# m1 V6 m( J  acceleration             ;; the constant that controls how much a car speeds up or slows down by if  }% v2 {& P$ [" z; y
                           ;; it is to accelerate or decelerate
2 X& N  b1 {! l' ?% {  phase                    ;; keeps track of the phase# `% ^/ h* _' I' k; ^% R  p  i
  num-cars-stopped         ;; the number of cars that are stopped during a single pass thru the go procedure7 b; p7 ]$ y5 Z5 d
  current-light            ;; the currently selected light
- [5 g3 N1 F% t1 `& ?/ ^7 W( c
  ;; patch agentsets% n1 N0 _7 {% w, p1 Z1 |
  intersections ;; agentset containing the patches that are intersections
/ r7 @2 W$ m$ c  roads         ;; agentset containing the patches that are roads: H" l' ~* f7 M9 Y: |0 X  K$ H4 _
]" \% n5 d% T' v5 Y8 a' @! Q& D

" }4 K5 k( i8 `, Jturtles-own/ V6 d0 q' @7 Q; ?& l
[
' b) o3 P4 g0 l$ _& {: i  speed     ;; the speed of the turtle  C$ K  N+ u& h# p
  up-car?   ;; true if the turtle moves downwards and false if it moves to the right
; o0 u$ C% t# Y, \. S; U+ g  wait-time ;; the amount of time since the last time a turtle has moved
+ O: }; |3 ^3 ]' ]0 W" _( @' Z2 \& E]# r0 F$ n6 h# `+ R7 d" z

, W  f7 h5 N5 [1 R, bpatches-own
1 p& R' S; _. x# z  S  h& S[
0 Z' K8 J( A0 {# C0 R' e  intersection?   ;; true if the patch is at the intersection of two roads( h6 N$ L; }6 \/ u8 ]
  green-light-up? ;; true if the green light is above the intersection.  otherwise, false.% E0 D+ k7 B* y) ^8 I# E# `
                  ;; false for a non-intersection patches.
, H. j3 l: w! U& S  my-row          ;; the row of the intersection counting from the upper left corner of the
" T! ?6 {9 ?! T' c' T* j+ x+ i5 T                  ;; world.  -1 for non-intersection patches.
. y' w, d2 c. T7 G$ S& T( O  my-column       ;; the column of the intersection counting from the upper left corner of the
3 m/ x$ U9 y6 t' e* G                  ;; world.  -1 for non-intersection patches.
( u* [' p9 ]# {- \* D0 ~  my-phase        ;; the phase for the intersection.  -1 for non-intersection patches.
6 x0 o9 V1 E$ u, L3 ]/ R: e* a  auto?           ;; whether or not this intersection will switch automatically.
$ ?' e+ A' ]" e+ C2 I                  ;; false for non-intersection patches.
$ t) V  I1 C+ D" }1 Q' v& h" G1 X]
' x- q7 N% ^! K4 f* s' J1 e0 P+ G' e  Y

, N- \! I! x0 [) C4 ?: [# K% u" f;;;;;;;;;;;;;;;;;;;;;;7 N5 B) \0 D; _( T& ~
;; Setup Procedures ;;
; J) I1 r: ?6 x; T" M;;;;;;;;;;;;;;;;;;;;;;- C- [0 j3 [) E) P2 g* r9 m

7 ]' F+ ?: Q7 S& `  G;; Initialize the display by giving the global and patch variables initial values.; S7 w, x* R9 G# z+ Q4 A( W; z
;; Create num-cars of turtles if there are enough road patches for one turtle to+ d9 X/ g5 x- F# b, u4 f: X
;; be created per road patch. Set up the plots./ J% p1 }0 u/ V' }+ C+ t" c/ Y
to setup4 K% J1 E# z" I6 Y8 n6 n8 t) e
  ca
8 f4 @0 v$ f1 B2 Y% e" S5 b  setup-globals
7 j4 ^+ B* X0 s# }
9 L4 X( x1 m1 I3 l  ;; First we ask the patches to draw themselves and set up a few variables
9 c& y% i. O# w, \  setup-patches
2 y. J) f; q0 z- H; k% \! r  make-current one-of intersections  X; ]5 W" Q4 J4 v0 n' ^
  label-current
! ]& F+ ]) b  V. w7 d) J2 m4 M
, G( f! W- J. h  x# s: c$ z  set-default-shape turtles "car"  }# L8 b- {) b: D; N" H9 s# x+ H' T
, t" ^( L0 S3 Z4 N: t) z9 l
  if (num-cars > count roads). }6 a% r7 D0 L# T- Z, {# B
  [: H2 I7 C% ^4 Q
    user-message (word "There are too many cars for the amount of "6 u4 l! u7 T6 H% r
                       "road.  Either increase the amount of roads "$ E* m% {% k$ [$ I4 o7 e6 O
                       "by increasing the GRID-SIZE-X or "8 X  i0 \2 n& V& y5 t6 M5 h% i
                       "GRID-SIZE-Y sliders, or decrease the "- F7 v( W( R9 R3 b( N2 k0 A
                       "number of cars by lowering the NUMBER slider.\n"
5 U8 X: E. @3 |! Q! u& C                       "The setup has stopped.")
% g" q" {+ \" p  \! B3 c+ G6 A    stop
6 r+ R) H6 [% H. _  ]4 i9 Q4 e0 s* t

* @* |6 a2 ~  e0 Y; s0 P5 X2 A  ;; Now create the turtles and have each created turtle call the functions setup-cars and set-car-color' d/ Q& G/ q* I' F$ ~5 }- D
  crt num-cars
8 p2 k$ T; Y$ e  [
) e. O' h4 ?5 h7 D" Z' k    setup-cars  ^  `. j7 D' T9 {6 ?0 B( b* }
    set-car-color! N* c( |% H8 b0 @0 h1 O
    record-data- s0 @: ~' [- `( n
  ]
0 n3 x, a$ G" J( [: n& A; C9 S( z  K" t9 T: [, r- Q
  ;; give the turtles an initial speed
7 \8 @. W! N; T; ]) ]0 n  ask turtles [ set-car-speed ]7 K; n0 U& H" U) r
) m& t6 a5 L! \+ M9 I' C- [# Q* m
  reset-ticks
$ M1 z6 w0 M! H' R9 r' ]" bend/ h1 n- f: }2 ~& D. }7 X" O

; [5 _' A. Y& m2 T2 v;; Initialize the global variables to appropriate values
# ?: K7 e6 e8 ~6 ~to setup-globals9 r/ n3 _8 R9 z
  set current-light nobody ;; just for now, since there are no lights yet
# m' C( H  z% w6 v5 u  set phase 0: A3 e3 R& H. t- `( T
  set num-cars-stopped 04 j. P8 ?: a2 K' y( q
  set grid-x-inc world-width / grid-size-x! m  y# Z; W& A% L7 K
  set grid-y-inc world-height / grid-size-y
1 |* x1 \0 A- ]
/ _& S% o: L5 a$ n  ;; don't make acceleration 0.1 since we could get a rounding error and end up on a patch boundary
2 n$ {9 V8 n. P( V+ H  set acceleration 0.099/ K# S$ ~& ~! r1 C1 E: r: }
end
5 e' V3 `/ S  k  R$ e2 {' d9 O" a: M8 L! [- ]  p# e5 E. Z, g
;; Make the patches have appropriate colors, set up the roads and intersections agentsets,
2 G- j* P8 w: c) S: k' V5 T5 P;; and initialize the traffic lights to one setting
5 l: q0 U7 Z% @0 _to setup-patches
2 J& \# B( C3 c7 g& N8 y( O7 Q  ;; initialize the patch-owned variables and color the patches to a base-color
6 I! S- O6 s* c6 X8 I7 X  ask patches
, m1 I# e9 b6 h" Q' ]4 i3 n  [
$ l$ Z6 [9 C& ?  K    set intersection? false, R/ `1 \9 Z3 F
    set auto? false2 C8 W8 f4 a! Z6 O5 H0 E. E
    set green-light-up? true
# A$ {& s$ ?- j! I1 i5 ?$ l) S    set my-row -12 q. o: e$ ~( E2 u3 C! ]  Y
    set my-column -13 t$ C  t4 L5 q; T2 ~) n3 W
    set my-phase -1+ U% P" a  i5 r8 l+ T% s: j
    set pcolor brown + 3
! k4 H4 I$ l" k, ?5 X. B  ]
" Z, Y- {2 t, B, ^; F. ^& P* d4 T) ?0 f
  ;; initialize the global variables that hold patch agentsets
# k/ }7 `, }6 e! `( w5 O1 A* Z1 \  set roads patches with
7 u7 }0 w, r) V% Y    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) or
9 y  B/ O& E4 p$ O' U2 U# r) }    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]* q7 T/ v5 x+ m3 ?9 I/ m" ?
  set intersections roads with
- l. t$ {& x! n5 P8 m4 u    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) and
) N7 k1 s# }3 a  w3 m: ?" Z    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]+ v# p3 O3 c. {+ G4 K& n

! X! V, x7 F- |' s5 p  ask roads [ set pcolor white ]4 |6 G: Q( i* i' O0 t, ], _
    setup-intersections
- B8 [" \7 B' mend, h; }& ^% g: y* L
其中定义道路的句子,如下所示,是什么意思啊?
7 ?/ `2 i$ E, Y0 s9 w- A set roads patches with
/ V( e$ T( Q( v. k+ C! b  O9 _    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) or
+ n4 S+ ~* ?/ x+ z' l" M    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]% V& I2 C6 U& X$ f# B( K
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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