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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。% n6 I3 O+ ?/ c3 x7 A: P
netlogo自带的social science--traffic grid这一例子当中,
: }* g/ x/ D+ v! m) aglobals2 X2 l% I$ z! B3 Q/ Q% i4 b" S0 L9 u
[
+ F5 ^0 N3 K- T( g$ ~3 M' N  grid-x-inc               ;; the amount of patches in between two roads in the x direction+ M# `  K& ~+ e9 q9 l& E9 \4 p
  grid-y-inc               ;; the amount of patches in between two roads in the y direction
- ?: D1 G# s, h0 A0 ~  acceleration             ;; the constant that controls how much a car speeds up or slows down by if* M7 w7 k1 Y% W
                           ;; it is to accelerate or decelerate
+ q: k) k4 h' t. B* [4 \  phase                    ;; keeps track of the phase
5 z% |6 a8 A+ p( \! O2 C! z  num-cars-stopped         ;; the number of cars that are stopped during a single pass thru the go procedure
; k( O* @: u' h- P( L2 l! l$ C  current-light            ;; the currently selected light, F2 l/ `5 b) A+ i' `# j

+ U4 a2 _' E5 e8 Z* F7 O  ;; patch agentsets
( u' I2 T; V( A  intersections ;; agentset containing the patches that are intersections
5 E- M+ x7 Q+ Z6 [* K, I- p  roads         ;; agentset containing the patches that are roads: P$ J5 r# |( V7 ?& z2 X
]
% @, Q+ }' t+ O1 y- f" J: d$ y
, d6 L4 x4 N' ~* e( h( L- I0 lturtles-own8 x  ?/ g: C9 |; T# P  G, l
[
8 ~% ?! E, o& J' ?1 X" V  speed     ;; the speed of the turtle3 b4 P; h5 R; e0 m- `" O# L) F
  up-car?   ;; true if the turtle moves downwards and false if it moves to the right0 q1 ]- J- p. h  e9 I
  wait-time ;; the amount of time since the last time a turtle has moved
1 u4 d4 @7 h0 ?3 C0 E$ ~5 r]' b) m1 q2 |4 E# K! W' _6 P& _4 p  l

4 `. ^7 ]9 k% o/ wpatches-own& ]" y, e# b( m/ r# A
[3 j. }6 f& a# P) ]* W3 J6 [; W
  intersection?   ;; true if the patch is at the intersection of two roads. x7 y9 z2 y, H
  green-light-up? ;; true if the green light is above the intersection.  otherwise, false.0 B6 S# j& ^" y7 N$ C1 H* Z
                  ;; false for a non-intersection patches.( \  h) R/ b$ n' ?+ ^! Q) L
  my-row          ;; the row of the intersection counting from the upper left corner of the
& J& N( |+ o' O3 T                  ;; world.  -1 for non-intersection patches.
* M8 U" Z6 C( x+ `; o  N/ q6 M% `  my-column       ;; the column of the intersection counting from the upper left corner of the  `5 s% U" {8 k* q
                  ;; world.  -1 for non-intersection patches.
& G, {8 H$ q5 l  my-phase        ;; the phase for the intersection.  -1 for non-intersection patches.9 |% C4 Q0 h+ g/ g2 U" p+ d
  auto?           ;; whether or not this intersection will switch automatically.
2 i+ _% T& g( }" S& P& m0 O+ j8 N                  ;; false for non-intersection patches.* [( `# e0 d1 j8 L% C5 F
]
6 G6 g1 J7 x3 j2 w0 ~4 |  G$ \3 C1 X$ q! \6 s1 r2 f
/ }" b; W& C& y; r2 @; o
;;;;;;;;;;;;;;;;;;;;;;
% B/ \4 ~% W* y; U1 D;; Setup Procedures ;;! P) P% p: h! L, n' F3 ~0 y3 E
;;;;;;;;;;;;;;;;;;;;;;) }& i0 y+ X* d. P3 t- M
, o0 S0 S: g1 \+ P
;; Initialize the display by giving the global and patch variables initial values.5 p  y+ c5 \6 q; L
;; Create num-cars of turtles if there are enough road patches for one turtle to
6 a' x5 h+ f1 V2 o* [( Z, e;; be created per road patch. Set up the plots.( U7 I- [8 f$ C  v) P* U
to setup
) [+ V7 S1 j- @- ^; x8 r% _  ca. z3 C+ U9 M! E& W
  setup-globals9 t5 x- P0 p/ E6 V7 U) f1 [( @6 L) [
8 N+ G, R* u! K8 O. U/ }( o
  ;; First we ask the patches to draw themselves and set up a few variables6 F, ]4 q, G1 S9 Q4 {* S
  setup-patches+ Q6 G! Y( M1 q% ^& g3 P% D% t
  make-current one-of intersections
5 o. \, s* |8 a9 t: s* F) C+ M  label-current  z/ _) ?1 G: T7 u$ Q1 s
& i( ]2 w$ H) o) I
  set-default-shape turtles "car"
: g' Q! c9 I; g. k" q
' k0 g. @7 ]+ r4 O  if (num-cars > count roads)( X, u# J! k0 n$ i+ L
  [+ Y. q$ l2 H, X
    user-message (word "There are too many cars for the amount of "
  z7 t6 S3 z% A  X+ l6 t* w0 V                       "road.  Either increase the amount of roads "
! D; t% L8 x' d- k                       "by increasing the GRID-SIZE-X or "
+ w; T. `0 S, Q4 U8 `* W, P                       "GRID-SIZE-Y sliders, or decrease the ") a2 U' e/ W8 O; k0 y
                       "number of cars by lowering the NUMBER slider.\n"# `' x8 F$ y& e! B
                       "The setup has stopped.")
8 v+ e$ N" `+ }8 ?. D) r/ |    stop  a6 @. s8 `" e3 {: s
  ]1 V: D( h; J0 q& p4 d

1 s8 g# ?+ f2 F* P  ;; Now create the turtles and have each created turtle call the functions setup-cars and set-car-color
4 b0 h4 v9 A9 `2 a- P! \- p  crt num-cars  k4 b  h, ^8 R- F
  [
7 u- z: e5 _, T. s    setup-cars
9 O! ?: Y  e2 C% H4 N) a    set-car-color& n# b4 W8 E* @: H
    record-data* ]" t1 y4 Z) L$ n* \% O$ u' q
  ]
" W) u: @/ [2 v  T0 z  u' I2 z! q  }
; X, b- t; C) t  ^0 k  ;; give the turtles an initial speed7 |- n2 [7 u0 N% {: z: W- w
  ask turtles [ set-car-speed ]2 l* R) ]; A3 A1 K: \1 i

1 V2 m, r/ ?3 d$ }4 y& R  reset-ticks& P8 j5 b7 s* S  V; s
end
$ N6 o" j1 R( M! C! `0 {) _$ ?
& N& W0 i% L6 a;; Initialize the global variables to appropriate values9 n& E' V+ G0 j7 p2 j1 \
to setup-globals* ^: R- q7 P" Y; |( K$ ?
  set current-light nobody ;; just for now, since there are no lights yet
4 I5 `) }) S9 Q4 ~# j  set phase 06 ~  Q1 K$ Y' s2 k/ A( X
  set num-cars-stopped 0- k% }- Q& I( P+ N
  set grid-x-inc world-width / grid-size-x
4 x. ~/ [  z$ u& Q. \  set grid-y-inc world-height / grid-size-y
( C+ d& ?" h- \: m/ K6 Z( b
- Z( D- a$ F( H2 R  ;; don't make acceleration 0.1 since we could get a rounding error and end up on a patch boundary
7 b- N) K9 w' z" r) G' M  set acceleration 0.099
. h* e0 x, E3 @0 R0 kend
4 P5 L# N+ C5 e" E: _! q- t) a8 k6 q( e3 j# ]) @
;; Make the patches have appropriate colors, set up the roads and intersections agentsets,' o3 u: k9 x  U9 `6 ^/ L: h
;; and initialize the traffic lights to one setting5 ^6 P$ K0 O+ M" V; ?
to setup-patches1 Y& v% k) J5 \. @7 c
  ;; initialize the patch-owned variables and color the patches to a base-color6 _; h1 N  h" l8 F; g3 ]* ?
  ask patches' Y/ {6 J( i/ ]/ _
  [
: U" y/ W: j1 c. v    set intersection? false
) J: Q3 \  ]+ o7 O6 Q7 _    set auto? false
+ h0 l/ |/ M* f5 I9 z1 x3 _    set green-light-up? true
# h( R; d2 l) G  k7 M0 ], b    set my-row -1, C( U7 f2 @: L2 H3 t
    set my-column -1# J& K2 h6 ^( V) p8 B# K8 v
    set my-phase -1
$ _" W, e  ^; ?( N* M/ p) `    set pcolor brown + 3, A( i0 p# K7 Z$ ~/ |
  ]  M! M3 e# H( O; q* P/ v

/ g. b  W* n# d( m% e- E% a# I- |  ;; initialize the global variables that hold patch agentsets7 P1 d& ?4 e7 S4 p/ @" u' W
  set roads patches with
! L. r0 g1 X0 o  U& R    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) or
% x6 b3 a' z9 {    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]. y. E( J# j) ~3 l
  set intersections roads with
  U! ?1 t1 F0 O    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) and
9 O$ n- x! ?9 O5 ]( o6 I7 o. E    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]
: T) u' i0 r/ V! t; V3 D8 ^8 H
  ask roads [ set pcolor white ]
* D: G5 R+ L7 T/ s    setup-intersections( N( n; u# E) `2 s; a8 Q
end
5 Y- p+ x% k- W, q0 C5 f其中定义道路的句子,如下所示,是什么意思啊?
" b: |: k6 w/ \: h set roads patches with9 W2 q6 l$ h4 C; ?# L6 p( f
    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) or
% c1 X2 t5 I7 _; N    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]
* }5 J- T2 J4 z5 A6 [0 o- n! n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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