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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。+ u. `0 |5 l  D8 h5 t1 n* \9 ?. `3 A
netlogo自带的social science--traffic grid这一例子当中,
4 H/ d0 m/ y! t% y1 S5 `( kglobals
- t; A$ Z- g2 {2 g; a[
9 O, j+ p" _+ I$ y' t% M2 G* i  grid-x-inc               ;; the amount of patches in between two roads in the x direction2 q4 {9 f$ E$ @3 f9 F
  grid-y-inc               ;; the amount of patches in between two roads in the y direction9 N9 C# o6 J* p5 U8 \3 l- [( F) f
  acceleration             ;; the constant that controls how much a car speeds up or slows down by if
- |6 j2 a- L/ Y; ]& x7 L                           ;; it is to accelerate or decelerate
* m9 Z# ]! [/ P0 N4 C  phase                    ;; keeps track of the phase4 ^8 @, \  ]' c( i! M6 l
  num-cars-stopped         ;; the number of cars that are stopped during a single pass thru the go procedure
% |0 ~! a  t1 ~0 P: O" \7 Y  current-light            ;; the currently selected light
2 P9 G& N) D6 F( u
# W* I/ h# g! q  ;; patch agentsets
; k! u5 U! e, [  T! }' R  intersections ;; agentset containing the patches that are intersections
  s! o& Y9 `$ h/ E! J- O  roads         ;; agentset containing the patches that are roads2 N7 h3 y3 O0 H. t
]
  P! T+ d3 z' K
$ y# F' U; O4 Vturtles-own
3 S% Y+ P5 P9 E[: a' ^/ V( Q+ y- o* L
  speed     ;; the speed of the turtle& @) G5 C: [: F3 [% Q0 l
  up-car?   ;; true if the turtle moves downwards and false if it moves to the right  G5 i& m# }2 O
  wait-time ;; the amount of time since the last time a turtle has moved0 [+ J3 C! u% K6 }
]' ]3 @% h* W+ A3 Q5 L% F/ @

; {# K/ A& M  w- ?# e6 p& rpatches-own
* ~* |+ C) d: L$ W  v[
3 |9 c5 S/ R5 x* ~  intersection?   ;; true if the patch is at the intersection of two roads" w# Y! m& s: o; M
  green-light-up? ;; true if the green light is above the intersection.  otherwise, false.. {+ P2 d4 R+ s, E
                  ;; false for a non-intersection patches.
1 c: r1 a5 r9 R' M6 \  my-row          ;; the row of the intersection counting from the upper left corner of the2 \  @2 Y/ w5 l6 W3 t' I5 C$ Q; Y' \
                  ;; world.  -1 for non-intersection patches.: f; h9 A; e2 o3 f6 {2 r
  my-column       ;; the column of the intersection counting from the upper left corner of the
3 a. a4 L2 O0 g$ w' O                  ;; world.  -1 for non-intersection patches.' i) A& l/ ^, I. }0 X# \
  my-phase        ;; the phase for the intersection.  -1 for non-intersection patches.  w% B- _" ]3 F
  auto?           ;; whether or not this intersection will switch automatically.! y/ b, l/ W: I3 H
                  ;; false for non-intersection patches.
0 h' w- h. N" o" v0 X( l' V]
6 @; c  b2 \" M! ^
( ?) I4 Z2 D' b
8 W, ]7 Y5 G- G7 F; m9 Q. Q1 z;;;;;;;;;;;;;;;;;;;;;;& N: |8 H& \5 E! {$ ^! F5 r6 X$ f( X
;; Setup Procedures ;;2 M4 o/ x. y- c. M" R% a0 U# c
;;;;;;;;;;;;;;;;;;;;;;# _: E3 Z% j3 v3 }& `

2 W% Q/ @7 V9 l( S$ g* F& }  Z;; Initialize the display by giving the global and patch variables initial values.
: a! r  r  A' V; O' @& u;; Create num-cars of turtles if there are enough road patches for one turtle to
) X0 X0 p* D0 x3 ~  o;; be created per road patch. Set up the plots.
8 i6 h# e; }8 Y0 v- R. |0 eto setup
1 b$ _1 ]( q1 I7 q1 _( i) a  ca  k" h' x$ n9 C8 C. G9 G
  setup-globals
: I6 f$ ?0 T2 M# m) T" a/ Y- G# q8 G7 C
  ;; First we ask the patches to draw themselves and set up a few variables
- k  a: v; x0 x! b8 O  setup-patches
* i# C& N/ ]# A' T3 E) U  make-current one-of intersections
0 L" [6 ?! ~- p  label-current
' S) C7 \& p$ G( U& y! f+ J, N( b
  set-default-shape turtles "car"6 D: p7 @9 }9 B. Q  ]3 \9 ]% w
5 B/ d0 b# \# x8 c
  if (num-cars > count roads)' {4 f& I9 ~% Z
  [8 x9 |, K/ V) h- q3 ^
    user-message (word "There are too many cars for the amount of "
2 o: G% {6 h. v2 W                       "road.  Either increase the amount of roads "4 N$ I* q1 p+ R& ^
                       "by increasing the GRID-SIZE-X or "
: H& U* m! n; q( k* c& q                       "GRID-SIZE-Y sliders, or decrease the "
) \3 g' p8 V' ~) ?% {                       "number of cars by lowering the NUMBER slider.\n"
+ t. w7 Q  g  ^. v4 Q. ?                       "The setup has stopped.")& L7 n; F# S) j: o' M& f
    stop5 b) y3 z- F8 z5 c7 p. M7 A6 |& u
  ]
, B. ^8 E* k+ v2 W! D
0 s7 U& i9 w, q! G  ;; Now create the turtles and have each created turtle call the functions setup-cars and set-car-color+ W& _  \0 `: L. D2 M
  crt num-cars
8 Y9 x2 {5 d3 \+ d: u8 `  [
' r- _9 M! Z0 V9 Q! y( N& y    setup-cars
# W+ [- q. F! {- o# D    set-car-color
  f4 y- A, X3 I& q4 R/ p+ [    record-data6 I! ~5 ?$ ]8 J4 s. \. {
  ]5 N) h8 j- r: {  _3 X* T& F% \

4 ~9 x# Y$ I( W( G4 m6 m' z  ;; give the turtles an initial speed
& a* }; E8 u8 N6 Q1 I) W  ask turtles [ set-car-speed ]& H6 F5 B! \  d4 Y- r& U* N
) Y1 _$ L* ^+ r! y) n
  reset-ticks
% s: l+ `. x$ @end- m& k. B" c7 W6 u
& F; M. e, v7 z8 m" l4 _# W
;; Initialize the global variables to appropriate values
6 U" j" U- b1 `+ b1 Nto setup-globals
" k3 Q0 L  R$ f' p6 U  set current-light nobody ;; just for now, since there are no lights yet4 Y2 B. Q5 `$ F: C& f: x9 F% H
  set phase 0' \( x3 c  r  ]; b8 Z! ?
  set num-cars-stopped 0
5 i9 @$ E! T( r0 k( l+ W* |' V  set grid-x-inc world-width / grid-size-x+ W; X7 x7 D2 x. r$ U
  set grid-y-inc world-height / grid-size-y
5 ]- I, O: T# p1 _( z
6 V/ w9 [! k( B7 y3 a9 M$ V  ;; don't make acceleration 0.1 since we could get a rounding error and end up on a patch boundary8 _; T! T6 X4 A$ F5 N9 y
  set acceleration 0.099* I  l5 ]1 l' t& w# W: w4 g
end
/ \# ~: C$ j. k- }$ H9 t* L7 b
8 a( c; @, `5 b5 {' P& g( O;; Make the patches have appropriate colors, set up the roads and intersections agentsets,$ _5 Y# q; t2 P& ~( {' r8 D: d
;; and initialize the traffic lights to one setting& S1 x( N3 Y) p2 d$ R
to setup-patches
- X2 P: V7 `& X  C: l  ;; initialize the patch-owned variables and color the patches to a base-color/ `# s# M$ |8 ?3 q) w# e
  ask patches
/ |0 F$ h- p) ]/ G, t- w) Q7 K  [
2 r8 x7 V6 ~; O! ]5 ?    set intersection? false# y* S4 V5 O$ V; i
    set auto? false& f7 H3 l1 t: \. I! @
    set green-light-up? true
2 [2 F( ?( @7 L3 o9 l    set my-row -1
! b+ W8 C! g& F$ R2 o    set my-column -1
" F1 n8 O9 L0 w8 K    set my-phase -1# z$ Q- P% D: J6 z" w. x. l  W
    set pcolor brown + 3; h% Q) N! R# Z  Z+ J. X4 }% ~! q
  ]' H4 U% n( i" I8 r$ w+ W5 V" s. \8 }
& x+ o6 I- I, y9 E
  ;; initialize the global variables that hold patch agentsets$ K# B: A- s- \+ t
  set roads patches with& Q5 C7 Q: {8 H5 u+ A/ V
    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) or
6 B, X0 z0 o( I* J) @0 k    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]! B) a2 C+ ^$ ?
  set intersections roads with
6 d' i/ N" b5 W2 u* B2 O4 N, ]    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) and4 B# ]. n, o2 T# I' U$ B$ ~) m
    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]
6 d. N! a. T  T7 g# V6 f5 x4 _, P1 v8 c( H7 H! T& }
  ask roads [ set pcolor white ]9 Y* Q9 k9 T2 T2 g7 G' j6 C
    setup-intersections
7 D3 Z1 R" A( l+ ?. D4 \% D" uend- _* v" F0 b$ D- E, P
其中定义道路的句子,如下所示,是什么意思啊?
+ V! X- q$ C2 w set roads patches with
8 h$ |5 L* c( s    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) or
$ |  b! U5 Y4 e! W. q$ |    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]' k) K+ O# o; p; C2 O0 X$ V
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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