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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。2 ~. |5 t# n" f' O# W' n8 @
netlogo自带的social science--traffic grid这一例子当中,
5 G9 ?# r: |8 V9 _0 A8 Dglobals- n, @9 C: ]# u
[- M( t, ]! s* E& Q4 Y6 ~- |
  grid-x-inc               ;; the amount of patches in between two roads in the x direction
! z, W; L; t* @( p( {2 e* c- i" q  M  grid-y-inc               ;; the amount of patches in between two roads in the y direction
1 A+ h; }0 s- k) a$ @9 X  acceleration             ;; the constant that controls how much a car speeds up or slows down by if
( A: l! Z2 C+ X* R; S' J- F8 u                           ;; it is to accelerate or decelerate* m9 i6 X8 D8 q
  phase                    ;; keeps track of the phase
" }( i( _9 x0 ?0 Y3 I' r3 Z# K  num-cars-stopped         ;; the number of cars that are stopped during a single pass thru the go procedure
( ?5 |; v) T- \) @  current-light            ;; the currently selected light! @) N  \* f/ N
4 p2 Q  n, J3 ~/ l  n% x, J4 f' y
  ;; patch agentsets! r0 D* T4 W$ f' [$ \$ _0 I
  intersections ;; agentset containing the patches that are intersections
5 E  p: t8 |" |% N- X4 R. d  roads         ;; agentset containing the patches that are roads* {, ^. g' b8 W% l# H1 n1 V& x1 j$ H
]7 U4 A+ X" R, O
) ~; V# h4 b7 J) `1 ^
turtles-own
' A- S* h! R1 [5 F( D7 Q# C! D( A# H[
8 G+ z( [5 Q. e/ z  speed     ;; the speed of the turtle
1 D8 c- U* R# {6 a0 ~3 A) z  up-car?   ;; true if the turtle moves downwards and false if it moves to the right0 B. y4 x. a/ r% @0 ^' I" A
  wait-time ;; the amount of time since the last time a turtle has moved$ q" ]- V" h, z2 r8 b' P7 a+ U: }& o
]) d; K7 g* @+ t3 R

- X4 I. [" S9 C4 J7 X, L; e2 fpatches-own
, ^2 d8 G5 ?0 J3 G[
% {* i4 G) y$ H* Y, x9 G4 O  intersection?   ;; true if the patch is at the intersection of two roads
2 H, G2 |. L+ T0 Z4 q  green-light-up? ;; true if the green light is above the intersection.  otherwise, false.7 Q9 Z( w5 m. u5 w* e6 R, C) c) Y
                  ;; false for a non-intersection patches.. j3 f! p% o3 h) m/ y7 q0 j
  my-row          ;; the row of the intersection counting from the upper left corner of the
# e! ?/ Q: {0 B                  ;; world.  -1 for non-intersection patches.
1 d" w2 v5 J1 M+ @  my-column       ;; the column of the intersection counting from the upper left corner of the0 m$ v  W- }$ {: x  R) J
                  ;; world.  -1 for non-intersection patches.
  o1 J5 S6 ~) X) }# z  my-phase        ;; the phase for the intersection.  -1 for non-intersection patches.
5 Z& C, i6 j7 w6 o5 f; ?9 ?$ R. F2 x& h  auto?           ;; whether or not this intersection will switch automatically.( E3 b) b2 p# C6 {5 C( C  x
                  ;; false for non-intersection patches.2 z% _$ l/ ^, [) g  L2 D& l9 o1 ]
]6 h9 f3 K0 a* Y( A) t

5 H6 s' s, F" ]5 e8 q$ n2 d# q9 \( I  b3 [* K2 l
;;;;;;;;;;;;;;;;;;;;;;# I8 f0 h! l0 i6 f
;; Setup Procedures ;;
% {  N/ A+ x# Y' u& k, J! p6 B4 c7 M;;;;;;;;;;;;;;;;;;;;;;
: y' X3 P' a, v3 Q) `' q* E
# T: V3 F* j0 }- Y+ z! a;; Initialize the display by giving the global and patch variables initial values.9 S& @, `: s" o2 J, @
;; Create num-cars of turtles if there are enough road patches for one turtle to
0 ]4 x+ x8 B: c; Q( r1 {3 B' d" D;; be created per road patch. Set up the plots.) w$ @0 J4 r3 v$ ^, M4 j% Q
to setup/ d# @: l3 O0 @$ j- p4 G
  ca
- w, Q) o7 ~" o8 n- Z- s  setup-globals
" e- ^! y2 V/ J) o2 r$ D
5 N5 A4 _$ s0 R: ~  x  ;; First we ask the patches to draw themselves and set up a few variables
7 o6 z# W* E/ i  @0 o: k3 k  setup-patches
, n  ?+ A* [2 L5 r& E; y  make-current one-of intersections) c1 F& N4 d4 ?
  label-current
1 m3 r: t" [0 o% v  J, f1 t. D8 E# w# }+ r, P
  set-default-shape turtles "car"
" \# m$ Q+ p3 R9 x  i
9 X; _0 E& v- }3 J9 J  b0 D5 t  if (num-cars > count roads)
, u! c. b& K' s# Z6 k9 j9 Y  [
' c2 O# P4 h* M/ T9 n$ w2 B. ~+ {    user-message (word "There are too many cars for the amount of "* E& d% r* J& u% c$ E- V2 R* S
                       "road.  Either increase the amount of roads "
9 ~1 ]  N. K% R3 g( W                       "by increasing the GRID-SIZE-X or "
+ A8 J* W0 J2 D                       "GRID-SIZE-Y sliders, or decrease the "5 z1 r5 b: n( y3 x0 q" c& l# U) L+ a
                       "number of cars by lowering the NUMBER slider.\n"
+ d4 |/ n9 }' D* n! Z3 r                       "The setup has stopped.")  o& F; X  H$ O8 ^
    stop! }2 B3 ?( a8 C2 h6 i; n
  ]+ |4 h: `' q$ w3 N3 _! B
% i/ c1 o6 i( M- T5 p# o# i) A
  ;; Now create the turtles and have each created turtle call the functions setup-cars and set-car-color' K+ W" j$ W( N
  crt num-cars  [/ q. F: H, s: e# \9 }
  [
' i/ G& j9 D1 e* F/ b( b    setup-cars
1 i3 J/ m8 o+ D5 M# ?8 A* a    set-car-color5 ^: ^: `$ B2 h+ i6 x1 `
    record-data
3 U+ ?" H9 O  q2 J/ X) a# E2 f  ]$ \0 ?7 d) B) E! S2 S8 f

' C. B9 D+ Y: a  ;; give the turtles an initial speed
& K# S# I4 y- C1 r- L7 a4 Y! [0 n3 a  ask turtles [ set-car-speed ], @4 {2 B6 \; _3 s
: z, g- c1 F9 G4 }
  reset-ticks+ T6 Z2 O8 z7 W. _$ F" u$ U  g
end
2 C8 a/ t6 h$ F* R" X$ `1 a! \9 w3 f  Z& E$ c+ D
;; Initialize the global variables to appropriate values6 j' ~" C/ K5 E. [8 \' d' c
to setup-globals
; s9 S' T! Y& U4 d, _& ^6 R; K  set current-light nobody ;; just for now, since there are no lights yet* J5 y" [9 L& V0 ?0 X
  set phase 07 J# o$ X" y6 t- o
  set num-cars-stopped 0
8 ^. D6 L* X& D. H% L7 ]0 k  set grid-x-inc world-width / grid-size-x
6 i4 p( D# D* G  set grid-y-inc world-height / grid-size-y
* k  K% T% x# K4 ], Z& s1 @6 ^6 s& r. V2 \
  ;; don't make acceleration 0.1 since we could get a rounding error and end up on a patch boundary+ C0 Y6 ]' r0 [- |3 w1 R+ ~
  set acceleration 0.0996 i- b  g  m; F& s& l
end6 R5 K* C- y3 A" s- ^: \1 ?
, F" f3 |5 {! y0 d5 F9 ?( B7 G& x* o
;; Make the patches have appropriate colors, set up the roads and intersections agentsets,6 d8 Z; T" R. l1 V$ _% D
;; and initialize the traffic lights to one setting
7 \0 r- Z( p/ T1 x8 f' v: O8 zto setup-patches
7 K5 U4 k7 A/ Q) K  ;; initialize the patch-owned variables and color the patches to a base-color
3 v/ e, H6 Z: `7 w8 y# W) D4 U  ask patches/ o  E/ d5 y' g8 y0 v- T! [5 @
  [) y- T" a2 R7 |
    set intersection? false: d+ O, ^8 [- H5 v' i( [7 }! ^& W0 d) h
    set auto? false3 t5 J7 g1 e- E; Q2 C/ }% p+ A6 m
    set green-light-up? true7 M  C; K( O6 `) }
    set my-row -1
6 W7 V" Q7 f1 d0 x    set my-column -18 V2 R; G: x# p1 Y8 a
    set my-phase -1
' i; c8 n; [8 ~' E* A8 v* o    set pcolor brown + 3
+ q8 ~7 S/ H6 o  e: f) ?  ]9 ?. X2 F- k# w: z+ h+ h* i* x7 m# j

- _; B1 g( I/ B7 h+ i" G  ;; initialize the global variables that hold patch agentsets
9 T/ q7 o# ~! S+ ~# O7 v  set roads patches with; D6 T( H1 q1 Z: i* m
    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) or4 q- J  R) m4 b5 N/ v3 o9 T& R
    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]( Y8 D( V1 N# t5 `
  set intersections roads with7 ]( K1 n2 [6 D5 _- n
    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) and% c/ H- O9 V# B5 l, C5 g0 k! r# i
    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]. M& }9 y6 L$ B
1 p: J: n; e5 V; [4 {
  ask roads [ set pcolor white ]3 b9 G9 k- ]* Y' _
    setup-intersections
' e: w7 u6 ?5 O2 t1 u6 f. |end8 p& X6 o2 r  ~" H  {( o. }
其中定义道路的句子,如下所示,是什么意思啊?
/ |% y( A7 p0 b+ B5 E4 F& I- E set roads patches with1 }$ `- n. e5 W
    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) or
7 E: L; R  j$ H6 z0 i    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]
& F! N8 G* B# P9 Z/ ^3 S( r$ u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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