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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。/ l; W2 \. u5 h% X, j6 u8 R/ V. o
netlogo自带的social science--traffic grid这一例子当中,7 Q% g7 c5 y1 Y2 Z& p: T5 |
globals
2 H( v5 \7 q1 l% p, x[: G; Q; h& r% l. D
  grid-x-inc               ;; the amount of patches in between two roads in the x direction0 Q( Y. p. h+ V* v% c
  grid-y-inc               ;; the amount of patches in between two roads in the y direction
$ Z$ Z; b7 H) e# e  acceleration             ;; the constant that controls how much a car speeds up or slows down by if- P! ]* s$ G# d" j& A
                           ;; it is to accelerate or decelerate
! T  d5 @9 d" X/ A$ B% Z+ T  phase                    ;; keeps track of the phase
  k# S1 @, Y5 D$ a+ K; _+ t  num-cars-stopped         ;; the number of cars that are stopped during a single pass thru the go procedure
! p" V& ]1 D; k1 v! x  current-light            ;; the currently selected light
3 N  A( w  F/ X( X% j' I/ O+ S& T+ g: H
  ;; patch agentsets
; Y, }- {+ M6 E2 {  intersections ;; agentset containing the patches that are intersections
* L1 J$ I$ [# C  roads         ;; agentset containing the patches that are roads) A( n) s3 T# a$ e
]
* |- E$ Y6 _0 B3 n3 J1 @
( L) [( w( T% Z2 w! Vturtles-own: v+ C1 n- ?. \
[
! T7 U0 F4 f) h* B4 B9 L  speed     ;; the speed of the turtle
( l. j/ w# A$ x# y, Z  up-car?   ;; true if the turtle moves downwards and false if it moves to the right% v# v+ S  d3 i1 _2 c. _
  wait-time ;; the amount of time since the last time a turtle has moved
# v  q% P( |: N* G; `5 N]
/ L+ V* n3 w  F( N" t1 W0 ^
) c0 _. P+ _( C: Dpatches-own( O' \, T5 L. Y, D" X
[/ c2 m% ^& }1 q; w2 ?% L
  intersection?   ;; true if the patch is at the intersection of two roads
2 F2 l& p' W6 b( C1 b6 u6 C" \% b  green-light-up? ;; true if the green light is above the intersection.  otherwise, false.
9 u/ {& Z1 ~, ?; d: z- ]2 K                  ;; false for a non-intersection patches.
" m4 Z0 ]4 Y8 q1 j! {; \  my-row          ;; the row of the intersection counting from the upper left corner of the
6 ~$ ^, b; w5 o' Q4 o1 W                  ;; world.  -1 for non-intersection patches.
6 G+ C- Y, j& L; O( P. }& Q  my-column       ;; the column of the intersection counting from the upper left corner of the3 F0 C& H& w/ x
                  ;; world.  -1 for non-intersection patches.
: p9 ]# g! l6 z0 x$ M  my-phase        ;; the phase for the intersection.  -1 for non-intersection patches.6 U" n. L7 n  I3 X7 i8 B
  auto?           ;; whether or not this intersection will switch automatically.8 f* i# q) x9 R1 C, G3 Y9 @
                  ;; false for non-intersection patches.
/ b+ f) p$ s8 g3 n]
/ G! r1 Z2 p, x- `0 d! `( ?* Q: a5 I& E" H, O* `% b

8 Y5 x9 ?2 f- d. z2 X;;;;;;;;;;;;;;;;;;;;;;
0 c) e7 E3 }. J* Y# V. ^;; Setup Procedures ;;
8 ^" F- Y" U6 ~8 i1 L  E;;;;;;;;;;;;;;;;;;;;;;9 D7 f2 K, o% r! n( l- x; u
: _1 W- m/ f2 _5 D
;; Initialize the display by giving the global and patch variables initial values.9 Z1 f' c% N2 z2 U/ o9 P4 ~
;; Create num-cars of turtles if there are enough road patches for one turtle to
% P5 [7 o  R0 L& v( M5 N7 q0 |5 R;; be created per road patch. Set up the plots.& u. c: N  S; O7 _' b
to setup2 }; \: P; E9 u+ h
  ca4 m- k7 z/ a! w
  setup-globals6 B7 N; T  C9 P/ ~
9 k7 S8 O& w9 ]& C
  ;; First we ask the patches to draw themselves and set up a few variables
% C# u  w: }+ y: s0 M* k. T  setup-patches
) A; }: I2 D' F5 Y* }  K8 j6 a  make-current one-of intersections
9 Y1 ~# N) r; w0 Q  ?" E  label-current
/ ?  o  E- l& }- p; u7 Q" u; {
& t% q2 z' V6 o2 {  set-default-shape turtles "car"
% w1 L% E6 i6 C! [
, v" S2 ^6 H, }+ ^: U0 l  if (num-cars > count roads)
2 d! R' y1 s' f& E3 o- F  [  C8 P) U* U3 g! H6 B
    user-message (word "There are too many cars for the amount of "( d! D; r1 I6 _/ I
                       "road.  Either increase the amount of roads ": B$ v2 ?- L3 \7 l& t$ v+ Q- _, k( V
                       "by increasing the GRID-SIZE-X or "
2 y1 X3 D/ Q4 B* F( c# d                       "GRID-SIZE-Y sliders, or decrease the "3 s& Z: t8 s) i4 i. ^) x% {& i
                       "number of cars by lowering the NUMBER slider.\n"
; Y  S- D4 a) h/ ~" {' v                       "The setup has stopped.")' c, R& |7 t' l% X; o3 L% H- X( e5 V
    stop
4 T- q5 Y. U) u' f/ a  ]
1 q; u  a8 g9 i5 V3 c& ?7 [- e8 h) |8 k. @
  ;; Now create the turtles and have each created turtle call the functions setup-cars and set-car-color
* ^& g" h+ h: v) R8 U  crt num-cars  q9 W3 N1 t1 K" Y9 h! x3 Q( ?
  [; N. b# t/ K9 |" l0 ~4 m, a
    setup-cars
7 f6 i" [, ~8 A# k% k    set-car-color. N# \4 `6 M* z+ ?# i* v
    record-data
9 D5 ^6 D6 L( _" b2 m$ i. Q' `  ]" U6 B0 B( }- }. ^7 e/ t3 M8 Y& M
) O# b  z; {0 w' B
  ;; give the turtles an initial speed' v: h( u2 f' E) G: J% Q9 s. r  f9 S
  ask turtles [ set-car-speed ]" ~  L4 b/ J$ F# Q; A1 N3 f  B
' ~) [. |  C2 f  @
  reset-ticks
& \9 b$ B% h9 B& R, ]end
! G; W& p- H1 d. ?$ J8 l3 l( w8 m
% f  |2 ~3 a6 M8 [/ p;; Initialize the global variables to appropriate values
. F) S+ N3 B" t; Q) o+ }to setup-globals
0 y+ }; c9 V! Z1 }! J  F  set current-light nobody ;; just for now, since there are no lights yet. `/ F$ Y( H  @# [8 D
  set phase 00 I) ^; t6 @% @  L3 @- x) h. H: w
  set num-cars-stopped 0
+ F# X" P8 ~1 i9 }5 T  h$ H  set grid-x-inc world-width / grid-size-x/ B6 m7 T. g, Y" R
  set grid-y-inc world-height / grid-size-y
: \" s6 F  ]" B& I# G, ]1 Q8 w8 {6 X$ l" P. m& s
  ;; don't make acceleration 0.1 since we could get a rounding error and end up on a patch boundary: d2 E2 u1 i8 z0 Z# M; o
  set acceleration 0.099, P8 O# r2 T2 i/ o" l, ?
end1 ]" O% p% v  [2 E2 y  I

# o8 X' e$ ]6 C! p;; Make the patches have appropriate colors, set up the roads and intersections agentsets,
# x  h0 O: x" i8 M& e. `( y;; and initialize the traffic lights to one setting) j; Y8 a  d1 a# |! S
to setup-patches4 G: Z( h$ s1 `( N1 u- B! h, @' D
  ;; initialize the patch-owned variables and color the patches to a base-color
, U! O9 g2 q( E5 w* z( T7 _7 g  ask patches
$ b. v0 _' F/ A$ }- N( t  [; I1 S" E# C( w( Z# N8 m4 h
    set intersection? false- O- Y$ `6 S: n* |5 M
    set auto? false
/ X3 Q  B6 i5 H; T    set green-light-up? true3 Z/ l* t# s/ J% l: ]( O
    set my-row -1: {7 ~6 c$ @  R; P* H" o) f
    set my-column -1, c6 J3 y) M! d' o; ?: w5 C/ |2 w
    set my-phase -1/ k  Y  Y( j. ]* I
    set pcolor brown + 3
  u4 q7 l! I1 a$ {' k) Y7 _7 r8 E  ]
. ]# G4 O* k: C2 q
* E5 f! ^$ P+ ^$ ^% J; p  ;; initialize the global variables that hold patch agentsets* B- v9 V- F6 L6 P- a
  set roads patches with. U) j; ^9 ?% U: l# W* D7 O
    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) or
$ i& [: Q; j. ?/ s5 f5 w* L/ N    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]
. E' @9 \$ @1 D3 E) p# V% y* ~  set intersections roads with
) W( O% O; E3 g- q7 C+ |4 g; J    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) and# {% W7 U2 r+ q- R$ ^9 X
    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]
% [! j; [! K0 Y  ?; ^+ I# B0 P
. c; }. ?/ r5 J1 _2 P' Z  ask roads [ set pcolor white ]1 {, j8 z2 x2 z& M$ |" x! c7 W
    setup-intersections
6 m& B. Q+ G3 q( vend4 P6 a( r, \- K7 e/ _; O1 ~
其中定义道路的句子,如下所示,是什么意思啊?
/ U& B7 b, U- S0 m& @ set roads patches with3 D5 A; Y3 E: R
    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) or
/ e3 a" r% c( S- S8 I# ~7 [    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]
& D: O' v+ u5 E9 P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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