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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。
& r( {/ ^% X8 }0 ]& p" ]9 v3 pnetlogo自带的social science--traffic grid这一例子当中,
, ^* T: u; Y2 E+ Z( H; sglobals- n. g5 ?+ H* i0 ?/ s8 d/ I
[/ E  h- C* z0 ]- ~, P
  grid-x-inc               ;; the amount of patches in between two roads in the x direction
' X# N1 w; B$ B  grid-y-inc               ;; the amount of patches in between two roads in the y direction7 ]9 ]; l% _6 p; T  H
  acceleration             ;; the constant that controls how much a car speeds up or slows down by if5 _# I( j8 G; F' w3 f# }! ?
                           ;; it is to accelerate or decelerate+ ~" x5 [2 L6 u8 F* L- Y- x' Z
  phase                    ;; keeps track of the phase& M8 Y; i* G  {/ a; V: O
  num-cars-stopped         ;; the number of cars that are stopped during a single pass thru the go procedure
- `. j& b/ \2 ~' b. x- \9 b+ v0 o  current-light            ;; the currently selected light
; P2 t8 D8 v3 A' d9 M" T* F8 g) R. }0 H! c. q
  ;; patch agentsets3 H# G" m8 g0 g" f: q
  intersections ;; agentset containing the patches that are intersections# A! a* h3 c7 Q4 R
  roads         ;; agentset containing the patches that are roads
1 O2 c& W% Z) S, ^) f: C( G7 v6 u]
6 ~# W4 E# l$ a( E+ @% S* x  M" m& i8 [/ `, R# n6 `
turtles-own
1 G  b. P. f2 [# G/ h1 ^0 e[: @* v1 Q8 \2 [6 {; C# z" M4 X
  speed     ;; the speed of the turtle
2 I$ |) f) J1 S6 d9 m9 Y3 q  up-car?   ;; true if the turtle moves downwards and false if it moves to the right
- ?2 y) H" ~, V; |% [$ @0 ]. j  wait-time ;; the amount of time since the last time a turtle has moved! t8 F" O$ |: B
]+ S+ b; K+ X4 {
( ^' V% T- }* J
patches-own; T& K: [! g4 X( p. K
[8 P& O# _6 a8 N$ B
  intersection?   ;; true if the patch is at the intersection of two roads
! K; l# D/ W: L4 u& o) [" ?  X  green-light-up? ;; true if the green light is above the intersection.  otherwise, false.
8 b. L/ S7 d. k1 @  m% S% C                  ;; false for a non-intersection patches.
3 d4 S- y8 D: p8 n1 I+ r  my-row          ;; the row of the intersection counting from the upper left corner of the- a% M* @8 E# s$ w. _6 u
                  ;; world.  -1 for non-intersection patches.
7 {6 N6 s7 j  m- J; t7 [& h. l  my-column       ;; the column of the intersection counting from the upper left corner of the! d  b5 o' x% j- B/ o1 C
                  ;; world.  -1 for non-intersection patches.
) \# P) N+ C2 z- l  my-phase        ;; the phase for the intersection.  -1 for non-intersection patches.  S0 W  [- |6 s, J) D
  auto?           ;; whether or not this intersection will switch automatically.1 C2 K2 \' ~, |$ a5 q) ?
                  ;; false for non-intersection patches.$ P# ~( b7 r8 L6 A1 c2 O
]
/ R+ c3 ~) E% E) h& w' B' z0 ]* g6 g$ m/ c+ f* F3 t
7 c0 G: V: ^0 U. M% e" ^1 F: I" e% i6 g" K
;;;;;;;;;;;;;;;;;;;;;;
' g7 I: p9 X! z/ h* v;; Setup Procedures ;;# [1 H+ ^, w" E  d. v
;;;;;;;;;;;;;;;;;;;;;;9 o# l% u7 H0 b) i, R
0 I) ^; i# U: V6 x
;; Initialize the display by giving the global and patch variables initial values.
( G- N# N2 b4 q& H* v0 e/ `;; Create num-cars of turtles if there are enough road patches for one turtle to
/ k9 {" ^) U$ @( j, o9 R6 O;; be created per road patch. Set up the plots.# I3 z) e4 u6 H' w6 \0 n& K+ [5 k% G
to setup# e. a1 k, O" K* m7 M
  ca5 E1 b9 G! k  c; t/ t; L
  setup-globals
, z  c* B) ~2 i8 b" ~  i' V
+ _# i( r- l. P5 `  ;; First we ask the patches to draw themselves and set up a few variables
9 j# _/ a, o6 s3 ]9 f  setup-patches
" J0 J1 Q' u. |6 ^  make-current one-of intersections
4 ?  c! f- \# r2 U) R6 p  label-current" p! [  j2 x! ?# O( _) b$ d+ Z6 ]6 w
. w4 w, B6 N# k4 o# y+ Z& W: x& V
  set-default-shape turtles "car"
" B0 I4 l9 q& ]$ N' i: X9 m4 ~3 V" @. W$ A$ z/ o+ G* s
  if (num-cars > count roads)
' R) v5 y( v* y6 p6 @; y# G  [
1 ?" G! J0 z2 }    user-message (word "There are too many cars for the amount of "8 y5 }" o8 u& F- ?! V9 |( R
                       "road.  Either increase the amount of roads "0 v& j( b7 J* T+ Y. `
                       "by increasing the GRID-SIZE-X or "( i) p; d" n1 v, ^
                       "GRID-SIZE-Y sliders, or decrease the ", r: V4 `+ o% a6 u" q. C
                       "number of cars by lowering the NUMBER slider.\n"% l+ `, s1 r" f
                       "The setup has stopped.")
5 s* o7 m( B* D3 b    stop5 Y! C, }# q5 _& J! @4 O
  ]
! E6 b5 Y+ h6 M: Q
  z: d  k1 S' J$ R; h' S  ;; Now create the turtles and have each created turtle call the functions setup-cars and set-car-color
7 s  Q! a& p$ X  crt num-cars. |9 C- N! k! P( f+ l* `
  [) J: N( U" c# D
    setup-cars' M, K. D' F# p( t# B6 G& {' N
    set-car-color
1 `3 p5 k& L3 x# B  T    record-data: O9 q- b: q4 z: x' A3 j! D
  ]
( G% n8 s( g; r+ ]# C$ s9 ~* d  b* ^! x8 ~
  ;; give the turtles an initial speed
# A# N0 l5 E% h1 }0 Y  ask turtles [ set-car-speed ]
2 A; \9 T  r! c' u9 n' d! ~7 B. o2 e7 f' _) G* W  Q
  reset-ticks
& w: y0 c+ k& p; w1 D0 S* Q1 |end
/ o8 Z+ G+ t4 D9 H/ f* E0 f! M& q4 A  t* M+ t" o
;; Initialize the global variables to appropriate values
# b8 A6 k6 y; b9 y2 pto setup-globals
% ]+ H* x  O! e, _5 v1 d  set current-light nobody ;; just for now, since there are no lights yet* b$ G" ~: {) B$ [- j: C
  set phase 09 n  Z9 n, t+ S' o* b: ^1 ?5 O
  set num-cars-stopped 0
4 g' _! n" x: u$ {" z9 M. v  set grid-x-inc world-width / grid-size-x
1 q+ |* a. l* p  set grid-y-inc world-height / grid-size-y
$ y8 k2 }% c7 Q; N
" l3 ]% X9 v& g# T  ;; don't make acceleration 0.1 since we could get a rounding error and end up on a patch boundary: ?' u6 @! w, P$ U! W! d2 J
  set acceleration 0.099, ?$ S/ G& j" M' h( l* I
end% r8 {7 C3 O( I4 W- _* @
& i) \, r8 @, ]' w* q5 v. _" e
;; Make the patches have appropriate colors, set up the roads and intersections agentsets," c$ s) d! Y4 w7 k
;; and initialize the traffic lights to one setting
& d8 L, z5 B1 H7 jto setup-patches
1 V2 J1 i' C3 a7 F3 |. J& ~! Z  ;; initialize the patch-owned variables and color the patches to a base-color
( N7 P8 |9 q$ Y# Y- O2 ~1 q  ask patches
1 S: D( c* W2 I% f" y) z& p  [8 T3 N6 }0 e. Q/ b7 _' d) N9 G
    set intersection? false
3 _& z: i& T0 D% o  a% C    set auto? false
$ a4 I3 s2 u& ?1 w' w% J    set green-light-up? true* }- ?5 \0 _$ z: Y( a# y
    set my-row -1& q4 l) ^6 F5 `
    set my-column -1, Q4 e4 I% @* |! p! J4 K' |
    set my-phase -1
4 e, X. c/ G4 R$ L7 q    set pcolor brown + 3" C" u3 V* H* A$ Z$ e
  ]
1 ~% \. v  d* Z# w4 x9 S
9 ?) e: y* M. z) M- `5 I7 E  ;; initialize the global variables that hold patch agentsets
1 l! A7 Y! ^' w0 B2 a9 t( B$ I  set roads patches with9 n5 I4 i6 A9 a) K3 O
    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) or
& B  S/ @0 _2 [  B' _    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]
! X# `+ j4 s& G( @  set intersections roads with8 s3 u: o9 y. E) @
    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) and
2 H" c# s9 O; A; n    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]$ W$ Q4 @, k: t+ \5 B: Y! @) u
1 @; L& b4 C! [: o! V
  ask roads [ set pcolor white ]4 Y! q. X9 _: s' c; F, b
    setup-intersections+ ?. D. }' W  m9 ]5 a. g) M5 t/ \
end
% ^, O: s" X8 t# [: k) d其中定义道路的句子,如下所示,是什么意思啊?8 l% U5 z6 u% |* S0 J; \6 u) D
set roads patches with
  G' d. ^" z0 a( p2 `  X) U) i& P    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) or
" z) D6 a/ G% E& Q8 _; ]    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]. @/ n: v' M2 t
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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