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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。
' J9 `( U& ^2 V6 Vnetlogo自带的social science--traffic grid这一例子当中,+ D& Z6 J: r; U( q
globals
/ y& _. V2 M; Q; a+ B, H5 a) h[& B' ~* F: Y7 x7 K# {& y0 n
  grid-x-inc               ;; the amount of patches in between two roads in the x direction0 }% d3 x. f1 ~8 Q
  grid-y-inc               ;; the amount of patches in between two roads in the y direction% `# q3 _$ E, a( D5 f0 n# r
  acceleration             ;; the constant that controls how much a car speeds up or slows down by if/ ~2 r) Y' S1 z! j
                           ;; it is to accelerate or decelerate
% P  |  _6 _* ]1 h) c, B. F+ B6 T  phase                    ;; keeps track of the phase
4 b  \/ {5 z4 s' H+ a' Y: P, E  num-cars-stopped         ;; the number of cars that are stopped during a single pass thru the go procedure
8 r0 Q) _& _" W+ \  f  current-light            ;; the currently selected light
% x7 l9 d4 U1 J% Z9 x& `) \$ a; P2 C
  ;; patch agentsets2 a# E. v0 t1 `5 @3 n; F
  intersections ;; agentset containing the patches that are intersections- C% r- u. f4 M7 U( X
  roads         ;; agentset containing the patches that are roads8 D: W, j5 Z5 z8 g  w+ b
]. f2 |6 o9 {) q& u5 V4 [0 ]1 C
+ F0 X! h$ Z. A0 S! I, T; H
turtles-own
1 [! W+ K" G' |& a+ q" p, P[: {& `2 L5 I7 a0 H, @* `
  speed     ;; the speed of the turtle* ]% i( }' R& D" A) w
  up-car?   ;; true if the turtle moves downwards and false if it moves to the right8 X( R2 u0 e& [4 W: [! u
  wait-time ;; the amount of time since the last time a turtle has moved
  y4 q- `0 {5 y5 b. _; ]* g]' \, \; `# D& {5 W6 S9 q0 o

! s% E! J" Y3 Npatches-own
5 T6 q2 R: e. h* H5 }7 U[& H) T3 J0 Y% [7 p4 h
  intersection?   ;; true if the patch is at the intersection of two roads
+ Z! q" E: a. n* |( {  green-light-up? ;; true if the green light is above the intersection.  otherwise, false./ j) h" d3 r9 J% L* g
                  ;; false for a non-intersection patches.
/ d( {. F; b9 r  E  my-row          ;; the row of the intersection counting from the upper left corner of the
+ x+ E1 _1 V: W( J                  ;; world.  -1 for non-intersection patches.
* \9 ~9 V, w5 r9 c' t5 K' @  my-column       ;; the column of the intersection counting from the upper left corner of the
. e- U) g* G3 ]                  ;; world.  -1 for non-intersection patches.
$ x! t! }: k9 r! S- {% S3 L9 ^  my-phase        ;; the phase for the intersection.  -1 for non-intersection patches./ p9 m# v9 I  i* g9 V. h
  auto?           ;; whether or not this intersection will switch automatically.: L$ |" Y1 Z/ S5 A- C: ?( b
                  ;; false for non-intersection patches.+ K# ?1 q7 |# [9 J
]- [4 X7 h/ ~4 x4 v

) w0 ~0 k3 k0 S& q& X9 I' K/ I. C, O  U
;;;;;;;;;;;;;;;;;;;;;;
# |  f, q8 H1 C' L! z# u9 _;; Setup Procedures ;;
/ i$ o) d* A7 O0 ~7 w$ b;;;;;;;;;;;;;;;;;;;;;;' ~* u$ I  D; g$ _5 n- |; R
2 V0 J+ l; ^, z2 i9 N$ i
;; Initialize the display by giving the global and patch variables initial values.+ ~! y, s( [2 T; y# Z
;; Create num-cars of turtles if there are enough road patches for one turtle to
( w9 e3 L. }! k$ q+ P( M;; be created per road patch. Set up the plots.
) @$ o$ T6 q' Wto setup
1 Z) T7 z5 X( O, I3 V7 F5 c1 b- ]  ca) O* R" P  }% a+ M) Q; {
  setup-globals+ P" e. U+ H* p$ d& K' M( |. ~
# a* V9 ]# E0 K$ x+ ~
  ;; First we ask the patches to draw themselves and set up a few variables- `9 A& z2 t5 Y# |2 x
  setup-patches
; j% G1 S, o$ M" r- F: v  make-current one-of intersections
9 B' C* h, ~( j. t% ~  label-current
" `5 a2 K) a( ^8 L1 ~0 T' x( U+ B7 e8 X
  set-default-shape turtles "car"& ^7 @0 s8 x6 H% x$ {

0 s2 F5 W, m: X6 `  if (num-cars > count roads). k! L$ v, @; f: H
  [
3 P% z* [: M6 A( k4 p+ u+ V( p  m2 F    user-message (word "There are too many cars for the amount of "
: s5 \4 P8 l1 X3 w( E9 s1 @                       "road.  Either increase the amount of roads "
  }+ }% ^3 t. {+ U( h4 H                       "by increasing the GRID-SIZE-X or "3 V. g1 [1 z3 U: [1 r
                       "GRID-SIZE-Y sliders, or decrease the "
$ K% `7 m- \2 C# Q. z9 P4 e                       "number of cars by lowering the NUMBER slider.\n"
/ g2 ~+ E9 I5 q0 ]# g1 `4 J+ b; ~                       "The setup has stopped.")
1 Y+ {3 W  d. f) b& Z) @: Q    stop
, b: ]# i5 M3 y  ]
6 M( _1 p1 ~7 y. Y& c+ H- i/ X0 O$ D5 A
  ;; Now create the turtles and have each created turtle call the functions setup-cars and set-car-color8 K5 H+ z+ @( ]6 V# F$ J* ^2 E
  crt num-cars( m. d! |& e; F% l
  [0 E3 M, K) P) g/ U6 ~. l6 s; H
    setup-cars
& a9 \7 e- R( n- Z6 D& I) T    set-car-color
$ k8 S8 L1 n" ~0 W' c* B    record-data
' n; P4 |9 C! Y, @  ]
5 M2 {  e2 Y$ W: c8 T' _* \% U
# S- C: z& s8 p$ F* e. S  ;; give the turtles an initial speed
+ z! ?- W2 H" y* s2 f+ ^  ask turtles [ set-car-speed ]- a1 Z3 ?' M& u' I9 r* D; H0 U
7 ~8 n8 k( j, K4 h& U4 k1 ^1 i
  reset-ticks
2 q; o6 @+ H6 p9 Yend
0 q. h% e) B' }5 m" Z8 m# u" I# B& ^$ E; O1 s
;; Initialize the global variables to appropriate values( S3 S; M' \! r# H+ s
to setup-globals
  J0 V0 Z! Z# c  set current-light nobody ;; just for now, since there are no lights yet
2 [* N& `2 I2 D1 D; o3 v! h- ?  set phase 0
4 q) X: x4 F1 p4 o: u: F+ E  set num-cars-stopped 0
" ?: z# M+ E) A. B  set grid-x-inc world-width / grid-size-x
2 ]! x3 r7 d& T2 f( }+ E  set grid-y-inc world-height / grid-size-y
3 A  a2 A6 |( ?' W* I! X( w/ j: [% m/ ?) R% s" t
  ;; don't make acceleration 0.1 since we could get a rounding error and end up on a patch boundary
7 X/ `1 M/ N( `  set acceleration 0.099
7 [, k4 _0 ?+ q: b' o  I& C: U2 jend
% @( t+ U8 L' \! I; A: M6 E. j) F8 b) z* w5 X' y; o) w: M. L2 x
;; Make the patches have appropriate colors, set up the roads and intersections agentsets,
- b( g+ ]6 @/ H) ?- k;; and initialize the traffic lights to one setting
$ E" h! k8 C. {& Q/ Yto setup-patches* ~$ }0 Z- V" ~! i1 i3 _0 `' K/ @
  ;; initialize the patch-owned variables and color the patches to a base-color
/ o. j/ D8 S* E. U. [* `) Y  ask patches
7 p7 ^) T1 K5 Z+ ~7 o  [1 B( l6 Y3 Q3 J7 m/ Y% x" ~
    set intersection? false4 W/ g, ?5 F5 t2 M+ D% \
    set auto? false  i# p1 P+ }& U8 ~, k, e
    set green-light-up? true$ p1 o4 t$ @3 p( |2 F4 [
    set my-row -1: ]1 c, l0 n5 A% G2 R1 L
    set my-column -1( |, u6 K7 T# G8 `+ ]
    set my-phase -1
5 ?' |) T3 J4 |  W1 d( [& g    set pcolor brown + 3
. o' w# G: I( S4 {# O% v  ]
+ U0 K& W6 `$ Y; t' s( X/ L2 R& K, r
  ;; initialize the global variables that hold patch agentsets- c) f) e/ s6 o: Y6 g4 l
  set roads patches with
; j& L5 @, G9 l9 p# p    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) or8 g- z1 S( P" M6 p* e6 ^
    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]
2 n# \8 n6 B- A* d) q1 y  set intersections roads with
$ a. N( O  @' s: y% d5 K    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) and
+ S9 U. G6 C% P' `5 n    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]
, J( P1 e! h) M5 H: s4 @( M4 k+ \+ l7 F# g% J
  ask roads [ set pcolor white ]( K; y8 Z8 e) h+ g7 z7 @
    setup-intersections
& V: J' n! }# a- dend
# d" U& }# k# F. ^" i  u其中定义道路的句子,如下所示,是什么意思啊?
" j9 F6 \# H3 O) ]* b7 f set roads patches with
0 A; c) u* x- e" c- I0 F4 ~    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) or/ H5 |) i1 q" a5 p; Q* }! K* T
    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]# ^  y/ A+ w. B% L8 b/ J! p$ g0 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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