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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。0 @. x- s! a: ~: N! w3 A# m# Q: Q
netlogo自带的social science--traffic grid这一例子当中,
8 `* d8 {! q5 t2 {3 Kglobals4 l6 ?2 J; X# T
[
  d, }* `: ?0 I& q- c$ v  grid-x-inc               ;; the amount of patches in between two roads in the x direction
9 ?8 H: i% |! z1 |9 S2 ?  grid-y-inc               ;; the amount of patches in between two roads in the y direction
$ s/ a& ]  f- g/ `  acceleration             ;; the constant that controls how much a car speeds up or slows down by if
' @6 }1 b$ n# }; U1 R                           ;; it is to accelerate or decelerate/ z0 M. F" X; L3 I; J- x" `8 X
  phase                    ;; keeps track of the phase. v: v5 I& }+ \, w8 _8 U0 |
  num-cars-stopped         ;; the number of cars that are stopped during a single pass thru the go procedure- I9 p8 L) i! ~' v
  current-light            ;; the currently selected light
7 j; w4 a% y/ P+ X, A
) E& I/ {' p* z" Q# l  ;; patch agentsets: T3 k9 j0 m+ I9 k5 j
  intersections ;; agentset containing the patches that are intersections
3 Q- |+ y0 T1 M0 j$ r! v  roads         ;; agentset containing the patches that are roads
1 Y. `# P$ k: C2 q]
, ?/ x( q1 T& q7 T# S2 B4 `" w3 d  U
turtles-own* L! r+ B( `, q, l2 a5 m# t# H5 \
[4 i; {) x0 Z# v3 b: `& k9 w
  speed     ;; the speed of the turtle  T# o; h0 P0 `. v
  up-car?   ;; true if the turtle moves downwards and false if it moves to the right
1 f1 t9 S/ T$ t  wait-time ;; the amount of time since the last time a turtle has moved+ F# j% `0 \0 `/ o4 {
]2 r, W- h$ N, x' E, S( y! [; l

* F3 ^% I. q; {  }. q" l/ Xpatches-own% t& \! g! h3 @/ M2 p; Q2 {
[
+ K1 M+ F! a6 l6 c  intersection?   ;; true if the patch is at the intersection of two roads/ ]' \+ K4 M; X" g2 t% D1 M
  green-light-up? ;; true if the green light is above the intersection.  otherwise, false.
8 X& i$ ^+ J0 J                  ;; false for a non-intersection patches.2 R6 q3 ~1 o) }3 y
  my-row          ;; the row of the intersection counting from the upper left corner of the
, ?* m9 ~+ ]1 V+ C; W                  ;; world.  -1 for non-intersection patches.
# ?* Q+ }. Y1 P. u) m  my-column       ;; the column of the intersection counting from the upper left corner of the
' F  q; w. Z, e! R( U! W! H                  ;; world.  -1 for non-intersection patches.* f9 D& @7 \/ N1 \6 G2 g7 f
  my-phase        ;; the phase for the intersection.  -1 for non-intersection patches.8 s, F, C: J; w! R$ _1 c
  auto?           ;; whether or not this intersection will switch automatically.
" q2 A8 f  g! n( n                  ;; false for non-intersection patches.
. }  o- w. Z. ^3 f  N) e]# y  e6 h6 F- F
! ^! Q# \9 F/ d& r/ R
2 F# z/ r; t: b; k6 s
;;;;;;;;;;;;;;;;;;;;;;
6 i! @9 f$ c8 |6 R" _;; Setup Procedures ;;8 p4 S$ ]! J8 p: U- C. z
;;;;;;;;;;;;;;;;;;;;;;
. A* t! ]7 B0 H7 w/ T: u; J4 |4 m; C! R. P3 N, S
;; Initialize the display by giving the global and patch variables initial values.; G1 i( \  V5 `2 Q
;; Create num-cars of turtles if there are enough road patches for one turtle to( i9 {: B5 K) m) ?
;; be created per road patch. Set up the plots.
# c  A9 v. m. f# T5 R* yto setup
7 V3 {4 c+ q! z  ca0 S! c' R' C  |6 m
  setup-globals( {' F" K6 T) b

- R/ C0 N: t& D  ;; First we ask the patches to draw themselves and set up a few variables
1 D/ J. T# ^# |9 M" g- _4 C- n! K% U  setup-patches
# m/ _, }9 @1 U; |  make-current one-of intersections
% }; R! u: c/ J/ r. }2 x  label-current
9 c3 _6 n! @, M7 O" S( c' P( z( X4 b9 V+ B: E
  set-default-shape turtles "car"5 d5 D/ h$ g" W% h0 G1 b6 U
1 Z9 c; {+ d+ y3 ~: [9 W. f' `- c, q
  if (num-cars > count roads)1 [( t! i& S7 X3 y; F( V3 [
  [! q  X% `- n) s/ a
    user-message (word "There are too many cars for the amount of "! H, s9 _0 P6 \  l- C
                       "road.  Either increase the amount of roads "
: x5 g; c) G1 H& B                       "by increasing the GRID-SIZE-X or "  H( w0 |& c2 k! P" C  A
                       "GRID-SIZE-Y sliders, or decrease the "
- |+ H  V6 q* z% v. o& i" }& n. o                       "number of cars by lowering the NUMBER slider.\n"* A3 @' h8 \1 P( J
                       "The setup has stopped.")0 n3 @: |3 f( m- _3 D/ T) {/ D: \( ^
    stop
# N/ V# h; p6 C. }  ]$ H" `0 M4 l/ {3 s' ]' Z' u. D7 ^

' Z% C  r& E4 X. d% r/ V  ;; Now create the turtles and have each created turtle call the functions setup-cars and set-car-color* T  l8 M! A- {
  crt num-cars4 K; P7 T: a* L/ K: e3 j
  [
3 [9 m! U+ m. R  U4 ^4 \* u) |    setup-cars1 a8 q$ y6 p7 ?- ~
    set-car-color
9 W, s# _* c* k6 U0 }# a/ X' R* o    record-data
# G( }0 e& }2 ]# n  ]1 D* P% W# @& q$ j: t# a. q  M
% M8 B0 O* W# z$ V' z
  ;; give the turtles an initial speed
  \; J: ?; r3 {% _$ g  ask turtles [ set-car-speed ]' c, Z8 R7 @5 \- e# [9 \
7 K  Q/ c& r$ A) C
  reset-ticks
# I! K+ P) O6 ?0 C/ ?. S# Mend$ f" ]- |/ r+ m& O- C* h* L
4 T; M5 {* E3 {& d; C5 N/ Q& E! ?
;; Initialize the global variables to appropriate values+ U& }, m5 }. W
to setup-globals
# x- B4 \9 J' P  set current-light nobody ;; just for now, since there are no lights yet" R1 V2 i* u7 a0 |% _
  set phase 0
8 _) r2 K2 |4 c# U' w& H1 n& u. b  set num-cars-stopped 0
6 x; I& Q1 u- Z; l- a  set grid-x-inc world-width / grid-size-x
$ r  t6 B3 v# o6 F( n  set grid-y-inc world-height / grid-size-y* W' D: \8 \* y) k# S( \1 b2 `
( `8 [4 ~' b6 o& P
  ;; don't make acceleration 0.1 since we could get a rounding error and end up on a patch boundary
" C( D6 e' b4 |& r( A# b  set acceleration 0.099$ y8 [# O( a! `% V. Q5 p2 ^
end
1 X2 d0 R3 {- V0 U* v. \+ ~& S3 S* R9 D, U) [. u1 c
;; Make the patches have appropriate colors, set up the roads and intersections agentsets,$ K5 B$ a# s6 b7 n  i
;; and initialize the traffic lights to one setting
' z+ }) i2 h: m7 B5 I( L" `* Ato setup-patches
2 w' J& C. t* M  ;; initialize the patch-owned variables and color the patches to a base-color5 s# r* h+ |* m2 j
  ask patches
! h" p. F7 u& B: x* i4 f; W! M  [" D5 }* z9 C: B
    set intersection? false; z5 t8 R. \& m- l6 Y9 K5 y& F
    set auto? false
3 B7 y0 S. `6 N1 s    set green-light-up? true
/ e5 R$ [  e/ P5 m    set my-row -1
' g6 E, R+ q. U0 e    set my-column -1( L+ E% w1 j" q+ A3 f* P0 E
    set my-phase -1: T7 U, @) }+ F
    set pcolor brown + 3
3 {& q  K& P- i+ A  ]! P( I$ u& l- z& Z' m: O, O

) U/ v$ u9 \  ^3 y2 h  ;; initialize the global variables that hold patch agentsets8 O+ z8 i( _) B3 u; T
  set roads patches with' g. S. K, @# ]( G' J
    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) or
" n- L+ a, b! I' w    (floor((pycor + max-pycor) mod grid-y-inc) = 0)], v8 \& `* A' T: O+ G* I
  set intersections roads with+ [# m+ h4 U6 }! b- O+ g6 U' n, s# [
    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) and
* u8 W: A- _, e& m4 s5 H    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]
: ^! X5 A2 U0 y
$ `  j$ b+ O  J9 x1 N, _, f1 N% s% [  ask roads [ set pcolor white ]- T( f& i1 e! X" p
    setup-intersections% `* Q$ }7 c* y6 Z. X& u; P( u
end2 ~5 M1 V) o. ?" _: G& W
其中定义道路的句子,如下所示,是什么意思啊?
) C" y0 v& x% K% N6 _9 y3 i set roads patches with
( D3 \/ A  g# j0 u, K7 b" X- e7 V( i    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) or
9 h. o7 {, [) p& O$ A% l    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]
& A4 I0 y( Y' u# e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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