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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。
' V- z9 }  {4 ?. @2 Knetlogo自带的social science--traffic grid这一例子当中,
# h+ z1 {0 _1 _globals
! [; X9 k; ?& V* u( _. q[" ^, _" |' g7 M3 b8 l1 O
  grid-x-inc               ;; the amount of patches in between two roads in the x direction/ D: I  j2 \5 B/ u  G+ `9 \
  grid-y-inc               ;; the amount of patches in between two roads in the y direction/ C, l: {4 O6 g  O) J
  acceleration             ;; the constant that controls how much a car speeds up or slows down by if
) Q: j/ z2 m1 j$ v                           ;; it is to accelerate or decelerate
* T- {0 v4 o7 l2 e  phase                    ;; keeps track of the phase
( ~) Q* z/ a1 D" @8 b8 i" g  x! g  num-cars-stopped         ;; the number of cars that are stopped during a single pass thru the go procedure
, B. g) I) z9 N3 Z- c* u  current-light            ;; the currently selected light
2 g! K, v+ E4 c2 H" N, n* m7 d8 }3 N( c0 r0 y; }' V1 |) D( u) A
  ;; patch agentsets+ x  `+ C# f& E
  intersections ;; agentset containing the patches that are intersections% u* `" p3 W2 T* d6 J
  roads         ;; agentset containing the patches that are roads
7 r4 Y4 F6 t6 [3 j]
+ u) U3 N  ]- K6 [7 ]0 s6 d8 ?# Z" z8 @" t+ ~
turtles-own
  T  X# v& L1 d* q4 r3 m[
% C6 w) }/ G/ p8 [/ N( j  speed     ;; the speed of the turtle, Y& P; d. n: V* ]
  up-car?   ;; true if the turtle moves downwards and false if it moves to the right
+ D. a8 `& v3 V  wait-time ;; the amount of time since the last time a turtle has moved* u& Q" h# e7 u! T9 n9 i
]
0 C3 C- ^5 o' L  l/ I/ j2 u$ s$ @
: Y" ?: A# [( @% K/ A$ Xpatches-own
% d* X4 Y$ Q5 ]+ C2 `" r5 r, p9 H[2 z9 S; o- P/ e9 F
  intersection?   ;; true if the patch is at the intersection of two roads, i3 _1 ^9 M3 W
  green-light-up? ;; true if the green light is above the intersection.  otherwise, false.
) @- Y+ ?' {3 V9 h; y7 Q0 k                  ;; false for a non-intersection patches.
- d" M. k3 j: F  my-row          ;; the row of the intersection counting from the upper left corner of the% h9 X3 K+ w# L) W4 M
                  ;; world.  -1 for non-intersection patches., Q2 S5 G0 [5 S  x
  my-column       ;; the column of the intersection counting from the upper left corner of the1 i4 M9 ]! [4 b
                  ;; world.  -1 for non-intersection patches.  g2 \( y' t* E  w1 C
  my-phase        ;; the phase for the intersection.  -1 for non-intersection patches.
* Z7 U; o2 o' n+ n  auto?           ;; whether or not this intersection will switch automatically.+ J8 }. A: C8 P. ^) ]! t; `2 m
                  ;; false for non-intersection patches." M/ l" Z- i7 f# [
]
; l* e( i3 P! O2 g9 m2 Q. e6 ^
5 z4 ^( O" t- Q, X9 o3 A
1 O  J0 I- y4 A* ?- W9 v;;;;;;;;;;;;;;;;;;;;;;+ H8 T1 l2 w* i$ e* D5 Q
;; Setup Procedures ;;/ i9 M0 M4 C/ i
;;;;;;;;;;;;;;;;;;;;;;
( d+ i5 o$ [, m- w- ]% O8 {7 g; [0 W
;; Initialize the display by giving the global and patch variables initial values.
: T7 k4 j6 f$ w+ H" v5 V7 y;; Create num-cars of turtles if there are enough road patches for one turtle to
' e. g7 L" D# T2 C/ p; \8 |* W;; be created per road patch. Set up the plots.
4 F* I; b& U& Z" nto setup
: A# z; H5 n) q/ _; }) G7 T$ h  ca
7 R& B% Z0 z, r1 \' W  setup-globals
& M- B! l1 N/ \% O, z% H9 }7 G; c- h4 x. P. P" \; Y! a6 K
  ;; First we ask the patches to draw themselves and set up a few variables' |4 |  x) X$ T6 k8 a# S
  setup-patches
0 W" Z/ H5 @+ B0 `: Z$ s# |  make-current one-of intersections7 @0 P/ S) f( m3 q
  label-current9 M1 H! K& f4 V2 _1 s: Q% C8 K( G2 P
4 X  ^0 l. b# u( \7 I
  set-default-shape turtles "car"# D% n5 [* S" V7 u5 u0 i0 J

. b0 r: w% U$ W: t  a* y  if (num-cars > count roads)5 P2 S7 h& f7 U" ]$ X- l
  [
0 ?9 _" x5 G+ x    user-message (word "There are too many cars for the amount of "
4 e- R0 L* l" M. C5 B                       "road.  Either increase the amount of roads "
1 V- b; }% N3 H  P9 s) @                       "by increasing the GRID-SIZE-X or "6 V! ~1 \2 Y- R/ J8 u+ d! {
                       "GRID-SIZE-Y sliders, or decrease the "# f8 V6 E. ~9 q8 d+ d% G/ W
                       "number of cars by lowering the NUMBER slider.\n"
) V9 G: _8 m6 |* ]                       "The setup has stopped."); o4 q3 x  n/ A0 ]" O. Q+ u0 l
    stop+ m/ b# d  t/ t
  ]
- H1 D& C- x: V2 v* b5 B0 m, B9 I3 x/ L/ N0 W6 z
  ;; Now create the turtles and have each created turtle call the functions setup-cars and set-car-color
* G1 P4 z, F; H* V/ w  crt num-cars
% u& P2 m/ K& v1 ]  [
! ]6 y& ?/ r& G) h    setup-cars- M9 ?3 t- T) o
    set-car-color
5 c2 _7 F7 Y  b9 ]" P    record-data
" {, W. L% a9 l$ A4 ^/ a  ]
' M4 N* U( _; M$ D# p  P; b, Q- D5 L
  ;; give the turtles an initial speed5 F% B8 w# j1 F7 {) Q# f
  ask turtles [ set-car-speed ]
1 o, R  k: ?1 J$ w  c, v3 D' S
2 `5 b. C8 _1 }  reset-ticks
% l) S- P: m; p3 z7 v0 Z. A# Vend1 j$ N" |$ {3 t) P- E* Q+ |
. l- l3 h- K: t
;; Initialize the global variables to appropriate values" Q) O& Z7 A1 b' O
to setup-globals3 w# V7 O0 d% Z9 W; b1 T' j$ R9 L
  set current-light nobody ;; just for now, since there are no lights yet8 B7 \3 J* \$ K& l
  set phase 0
, ?( ?: K+ \) D2 M. X8 V  set num-cars-stopped 0
  u) n* l/ s, [* t) D! A/ M) P" K  set grid-x-inc world-width / grid-size-x
& V2 ]& p2 u+ F( N  set grid-y-inc world-height / grid-size-y9 \; |, }0 @  }  T: c3 @& M- I! A

7 @7 p+ i- H( }; ^0 T  ;; don't make acceleration 0.1 since we could get a rounding error and end up on a patch boundary
  O5 {( ~# D) ^  set acceleration 0.099
& x" |( |" j! e* ~end6 ?' T+ N3 [0 O3 {# R! Q
5 i! a! }" z7 }' v- \0 O; O
;; Make the patches have appropriate colors, set up the roads and intersections agentsets,0 q2 k" C! T2 t6 M1 j* P* A
;; and initialize the traffic lights to one setting" }% z& z& n( H! o+ U
to setup-patches+ f" ~( m5 F6 T! y- y
  ;; initialize the patch-owned variables and color the patches to a base-color
4 N9 m' D4 [1 y6 g  ask patches
' u# B  X  ]2 V1 R+ x) ^" d  [
' f4 Q% B9 e6 q1 F0 D    set intersection? false2 K- ^) ]# z. ~1 |
    set auto? false; M- q1 W7 G; Z, S) j2 R* x- P
    set green-light-up? true
: ^  n- l" H: `: d; @    set my-row -1
+ {% t. N& E  i) X0 l  |0 _" X    set my-column -17 l/ g0 p6 g  K; H6 j1 q1 }, x
    set my-phase -1$ L$ C9 @) t" t) @
    set pcolor brown + 31 i$ k8 i9 G: F! _( x  i
  ]
, u0 u( m: ?8 d: r7 K' ~) p' o& j% T  l& n5 c  x
  ;; initialize the global variables that hold patch agentsets. S- B! c" p/ s
  set roads patches with7 A2 w4 h/ b" l9 a5 g% M% N8 \% I
    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) or; B3 h, v5 y8 X1 y9 U. t
    (floor((pycor + max-pycor) mod grid-y-inc) = 0)], d* E1 V# N$ s# n+ p
  set intersections roads with
  P& a5 X6 M% m9 n: v# F    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) and
, Z! C  C! E$ l+ O$ v8 d    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]
% U/ C" C. _9 n% \& \
  R. v; Z% V* O1 T. b2 l  ask roads [ set pcolor white ]1 z8 H& [& I5 P# I4 w2 C/ V
    setup-intersections& N$ T! U( J9 h+ a
end# E+ C# R: \. a  ^* m" Y! v) @. ~
其中定义道路的句子,如下所示,是什么意思啊?2 ^( g8 P8 h" @3 k7 {! h  c$ \1 P
set roads patches with
. d6 N2 V2 ~( @& z0 c! m4 O9 o    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) or
5 _: C) ]) t7 i9 u& X% X" F    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]. b* U! v2 r6 W# l; x
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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