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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。5 d! v) u6 H/ _$ |0 q
netlogo自带的social science--traffic grid这一例子当中,: E. a) b4 P, X% o$ H; c! K
globals+ Y- s4 v) {* m# \  g3 z
[
, I, X' B& a, {6 T; V  grid-x-inc               ;; the amount of patches in between two roads in the x direction
7 M( m/ m! S8 u  grid-y-inc               ;; the amount of patches in between two roads in the y direction0 V3 m% p6 H' Z$ x" [
  acceleration             ;; the constant that controls how much a car speeds up or slows down by if; F; ~% D/ d& k7 L1 N
                           ;; it is to accelerate or decelerate* P' H/ r7 x: `! [# x% n5 P
  phase                    ;; keeps track of the phase
) d" f0 n4 }- I7 ]4 c! H( p: F; V  num-cars-stopped         ;; the number of cars that are stopped during a single pass thru the go procedure
% K1 z$ i% j; a. W  current-light            ;; the currently selected light
" d" Y8 N5 K" w8 M
% ?7 J( F$ w) W3 `1 _% E  ;; patch agentsets5 s. M( k( F. B2 v2 i" Z% F
  intersections ;; agentset containing the patches that are intersections
! \& U1 S$ I; @4 ]& P* Q* H  roads         ;; agentset containing the patches that are roads
# A4 B- K; b7 s2 h* O) D: i- m]
$ ^) G4 ]  @# b% G5 Y8 N; z) W7 U' Y* B. l" Y2 W# e3 \4 A" v& ]
turtles-own/ {5 `# s9 x+ T3 H/ g1 r
[
" ~; u( i% L4 ]( Y  speed     ;; the speed of the turtle- ^% s7 O7 I% _* p( r1 t3 q: v
  up-car?   ;; true if the turtle moves downwards and false if it moves to the right
: H6 H- `. V, _% Y8 Q7 Z  wait-time ;; the amount of time since the last time a turtle has moved
' w0 d1 }* m' |3 O]- s# j" S: I3 P

* j) n- |+ m5 @5 s: E) d/ Opatches-own
6 E7 s8 }) q, s1 k[1 \  i& Z; V+ S* E* ]* [
  intersection?   ;; true if the patch is at the intersection of two roads: L. o: Q; }. |1 d/ ]! h
  green-light-up? ;; true if the green light is above the intersection.  otherwise, false.
+ _4 @( F  W! \4 |/ i                  ;; false for a non-intersection patches.
0 b# M6 s" b  e0 R- a+ b  my-row          ;; the row of the intersection counting from the upper left corner of the; _% v5 m1 i( _
                  ;; world.  -1 for non-intersection patches.
2 ]) m4 @9 i' d9 A& b6 s8 p4 n  my-column       ;; the column of the intersection counting from the upper left corner of the# |6 Z9 F; A9 H
                  ;; world.  -1 for non-intersection patches.
6 `9 R, M8 Q7 ^  my-phase        ;; the phase for the intersection.  -1 for non-intersection patches.
1 F. u. U2 O% |0 S8 y, w  auto?           ;; whether or not this intersection will switch automatically.
2 t) S: k( K7 j: m. Q  q$ T. B                  ;; false for non-intersection patches." b- p* \$ ~0 p* G
], b2 I2 E$ r6 _4 A* Q+ ]! J

) P* K9 @/ j5 d+ j9 _* K! i$ x
6 I$ C2 o3 Q; z$ f;;;;;;;;;;;;;;;;;;;;;;
+ ], i! ?( H- ?- c;; Setup Procedures ;;
) f6 I5 q' P# Z;;;;;;;;;;;;;;;;;;;;;;
9 O* ^/ V- G2 j% N" j( W$ B9 A5 d% ^6 j
;; Initialize the display by giving the global and patch variables initial values.: J) h' F; H8 N4 D5 w
;; Create num-cars of turtles if there are enough road patches for one turtle to
5 r3 C7 I2 f5 l$ \# J9 g/ t) g% p;; be created per road patch. Set up the plots.
: x+ z( |: i: ]' B# e% C, U; H0 {to setup: F( p" {. k8 w
  ca
! U5 |3 x9 \: ]% D. k- k  setup-globals% w( z3 V+ F0 W( h# B
% [# X1 W1 F$ R3 ?+ U3 ~% [5 ~
  ;; First we ask the patches to draw themselves and set up a few variables7 h' B6 D& r0 F) ^
  setup-patches
0 P( x! b  R3 n1 O. O  make-current one-of intersections
! o! u8 H) @' \; ]5 t! I& c  label-current
2 t6 T' _! G* x6 C  W9 A1 x: L9 @- A0 k2 c8 R
  set-default-shape turtles "car"
, Q# B. U0 X; ]
3 [0 X0 g& z* [: S+ o! ^  if (num-cars > count roads)
$ p/ O, u  L/ S9 d1 n4 n; d( r& b  [0 n7 l9 @6 J& G
    user-message (word "There are too many cars for the amount of ": q/ U  ]- ~4 A+ T3 v; F2 ?3 p7 |
                       "road.  Either increase the amount of roads "- {* C5 M1 c: ~, e
                       "by increasing the GRID-SIZE-X or ". a. _4 W" Q8 Q" u8 h) A# k
                       "GRID-SIZE-Y sliders, or decrease the "
7 @2 E5 ?1 f: r7 R6 X7 L; b9 J                       "number of cars by lowering the NUMBER slider.\n") J- ]- p2 l: S  I, y
                       "The setup has stopped.")
( K% B, m8 D0 u3 }" v    stop
6 b* b+ ^$ C6 z/ r  ]
, Z; e" D* z' b' E
% Q+ F+ F' A# s0 l. X$ z. I! ]) i( ]! ]  ;; Now create the turtles and have each created turtle call the functions setup-cars and set-car-color7 A  U+ B/ k4 T+ T3 \! V3 @( T
  crt num-cars0 g0 S7 N- ^+ o' |6 T) h
  [8 |* @$ O& S0 G2 h" w6 i9 A( F% e
    setup-cars0 t/ p% j7 X3 M  ?+ q6 \
    set-car-color
+ G# Z" B5 A! {! I    record-data( r/ V$ u! F0 ]5 A2 q7 S6 L" Z0 r% Q
  ]
5 l4 z4 d8 C0 h$ [" B7 V0 L* r% d) ~4 p" w5 k/ [% f
  ;; give the turtles an initial speed7 d# b* e% g& _
  ask turtles [ set-car-speed ]7 A/ e# t! b8 b0 Y0 D. b
3 |. S3 I0 D1 F/ k% }; `" K7 ]7 ^
  reset-ticks
! R  X9 R0 x6 K9 ~: A' J1 D4 h: vend! C0 v; C& h/ h
5 q7 g- g, k; H; [# t$ F) M( g
;; Initialize the global variables to appropriate values% b3 v6 ?  ]$ I) F" f/ m, \
to setup-globals4 ~$ l" o( n# B& n( V
  set current-light nobody ;; just for now, since there are no lights yet
& _9 _, _& A! u! ?5 }+ C  set phase 0
1 P6 q3 }1 V$ m8 c( Q  set num-cars-stopped 0
6 ~3 X& G3 U- }3 v& o  set grid-x-inc world-width / grid-size-x
* o9 c5 e* h- L: O+ }. ~  set grid-y-inc world-height / grid-size-y
) W! D4 R; H0 Y4 u& S
0 W/ s1 v$ \, V  ;; don't make acceleration 0.1 since we could get a rounding error and end up on a patch boundary
9 Q5 ~7 g; @- E$ j* D1 I4 @1 e  set acceleration 0.099/ v  s9 D7 g! a, G. d! p
end; `! T$ W' e, @% Z8 B
' u3 J  F( P  o" [- Y( ^  a1 t
;; Make the patches have appropriate colors, set up the roads and intersections agentsets,
9 O2 f( h9 Y0 S5 _3 P: E/ i;; and initialize the traffic lights to one setting
3 p! W7 H& v. Qto setup-patches
; O# B) G9 D  W, Z  ;; initialize the patch-owned variables and color the patches to a base-color
, b+ @0 h; [+ z  ask patches
$ B% }. k) u6 _  [1 v1 R' e3 ]$ m* p' z$ e5 u
    set intersection? false, W" h$ c& n" y8 D
    set auto? false
( y7 _' D" i! n5 J3 P0 f: b. q    set green-light-up? true$ ~/ P7 o' u+ D7 J2 N5 c( l: ]! t7 [
    set my-row -1
' N) d3 I! j7 Q. A) \, W/ ?+ ?5 l    set my-column -1
/ ?( q  D1 W' M' J/ K    set my-phase -1
: y# l& h+ ~2 q5 Y/ e) ^5 b    set pcolor brown + 3; r. N( @" P& s6 |9 {4 M8 |" h
  ]
: U' u1 ]/ u; T/ R2 k8 f6 E( s' G+ C
  ;; initialize the global variables that hold patch agentsets
$ ]* K, G( W/ g. l7 k" O% Y  set roads patches with8 g$ F/ I' v1 a' `% ^( K
    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) or
( J8 l: ~( f0 P0 z1 \    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]
+ d' Y, ?/ U* I2 \  set intersections roads with
$ H2 J1 Y" Y: t2 T0 s    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) and
) u9 K, C# b9 l* U( D    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]; M3 F9 m( v! N$ P! Z, b

3 }  j- r6 c0 r: U5 V8 J) n  T  ask roads [ set pcolor white ]
. v2 }; f# W; \* W- ^    setup-intersections/ B1 b3 X' d; \2 @& h8 d
end9 ^, E$ c( _6 H* j: E
其中定义道路的句子,如下所示,是什么意思啊?2 n0 \0 E$ K7 f
set roads patches with# u, ]# z9 i3 Q
    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) or
) }5 C' i; q6 h2 y1 o    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]! F6 t5 X& J7 N- p+ X, F
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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