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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。
' @9 ^2 G5 @" I& m- unetlogo自带的social science--traffic grid这一例子当中,
: U, C7 y  w! `! v$ Tglobals
2 O2 @- }; `5 M5 a  D9 u. U6 U8 M[
$ q/ M/ j) \; m9 S  grid-x-inc               ;; the amount of patches in between two roads in the x direction# I9 _/ p# E$ ^9 |" b" Q! z
  grid-y-inc               ;; the amount of patches in between two roads in the y direction6 ~+ R% R6 K2 I9 r( [" I
  acceleration             ;; the constant that controls how much a car speeds up or slows down by if% @; n# G3 r6 ^# M4 `
                           ;; it is to accelerate or decelerate2 {; M4 b! B5 o
  phase                    ;; keeps track of the phase
+ e2 f) c4 R# r; P3 _: N  C4 `  num-cars-stopped         ;; the number of cars that are stopped during a single pass thru the go procedure" c2 Y, T: O: h2 D
  current-light            ;; the currently selected light
( E4 k/ i/ |/ Q% W3 B% W3 J8 m
+ ^. [8 e$ i8 N6 [" G9 n1 W+ Y  ;; patch agentsets
6 T8 A  n0 T& e  ]' ^' g7 P: ^  intersections ;; agentset containing the patches that are intersections( S$ `6 x1 j. L) N' L
  roads         ;; agentset containing the patches that are roads! o- P- Q: ~% e
]
% ^, d3 `, u3 {, x5 G/ V9 F3 u% f+ N1 F
turtles-own
# W9 x. c0 M: C/ a" r, A2 s3 w[0 H% f; L  s4 b' _8 [8 C5 J( H0 G* a
  speed     ;; the speed of the turtle  v) ?0 H9 Q& q
  up-car?   ;; true if the turtle moves downwards and false if it moves to the right
$ Q) y5 {9 ?4 i9 c# h' E( `1 s* |  wait-time ;; the amount of time since the last time a turtle has moved
/ f8 U& \  i1 j* r9 |$ ^]
2 S  {! I- s% M. ~. c* I5 \& u" I% l8 g. b
patches-own
0 c! Y8 {- ?' h8 y+ c( l2 i8 E[+ `' a) e  T+ o/ X' ?0 Q
  intersection?   ;; true if the patch is at the intersection of two roads# |2 D6 B3 F8 z5 f
  green-light-up? ;; true if the green light is above the intersection.  otherwise, false.
/ ?, g+ c* E, J  e. a; ?- j* f                  ;; false for a non-intersection patches.
1 A0 u- ^* Y8 G! R  my-row          ;; the row of the intersection counting from the upper left corner of the
# S7 m1 E' r% W4 @2 `1 M% ^                  ;; world.  -1 for non-intersection patches.
: M/ ~1 g$ ^- y1 [& G/ K  my-column       ;; the column of the intersection counting from the upper left corner of the
1 B" |! u. ^1 t1 |! I! ?                  ;; world.  -1 for non-intersection patches.9 ]: Y; w0 r- _- X0 X! |& u- D
  my-phase        ;; the phase for the intersection.  -1 for non-intersection patches.
4 u" v. l; i, T- V. y. B  auto?           ;; whether or not this intersection will switch automatically.( K; z6 J& C$ b" r! G
                  ;; false for non-intersection patches.7 {% {( c. C1 W3 b
]; c8 ]0 b+ L5 P" o5 F! e0 {8 W) }
) B5 f% k2 a* W# y% h' n) h. `5 D

% a( J9 r6 U! O+ R2 S;;;;;;;;;;;;;;;;;;;;;;" q6 j% p6 B4 R5 |8 b9 O* W
;; Setup Procedures ;;
+ E5 V7 i/ V4 J, b" m6 K;;;;;;;;;;;;;;;;;;;;;;
+ c1 E9 [6 O% q  H# x0 e4 ]. h8 p" ]. p2 y: g
;; Initialize the display by giving the global and patch variables initial values.$ t! T( C! Y, ]# p% r: k8 X1 X) o
;; Create num-cars of turtles if there are enough road patches for one turtle to; t5 U# p/ s" i" n8 @7 a
;; be created per road patch. Set up the plots.
4 k5 R$ o/ v% n* U2 {to setup: h3 F1 p' x4 f8 G
  ca- E$ ~: w+ N2 U
  setup-globals
3 @% d; n* ]& Z+ p' v
7 r' U* b( [/ g: X* Q2 e  ;; First we ask the patches to draw themselves and set up a few variables( {8 A9 T( {. z2 Q: [
  setup-patches
4 V  i" b0 m# x% {. ^3 @  make-current one-of intersections
) z" l( n) t1 f( Y  label-current, x0 ^' Y- R9 V! R% j. b' p9 i
+ c4 K: w6 f! G+ ?! U+ @
  set-default-shape turtles "car"3 k" V7 T5 `  R" q. N
; N- C; |/ |9 p7 c
  if (num-cars > count roads)  q( J3 y6 g: _. d$ q
  [8 v0 }: G  H8 l3 H; R& W4 `
    user-message (word "There are too many cars for the amount of "
/ |% w  T# G& n9 P                       "road.  Either increase the amount of roads "
. Z. I* [# M7 g4 s( P                       "by increasing the GRID-SIZE-X or "1 {' {% T% l+ e+ G
                       "GRID-SIZE-Y sliders, or decrease the ": w' b1 X) p- g( K! T
                       "number of cars by lowering the NUMBER slider.\n"
7 c+ a4 q8 V- p                       "The setup has stopped.")& m+ q9 y& j+ S% x
    stop
  q' k4 f9 S+ E* ~* P8 i) W  ]
5 z; C6 X) @' _" q7 k6 b5 P% H, T" ]/ b" K
  ;; Now create the turtles and have each created turtle call the functions setup-cars and set-car-color
, Y8 _# q/ y" ]' L  crt num-cars4 G4 p- p7 @& u+ h
  [6 ]& E6 X2 ]8 C1 c0 H4 m. b
    setup-cars
+ V( Y2 [! g( A# _: U0 c4 q    set-car-color$ O# R; F: Z3 z' ?
    record-data& b% L8 R8 w9 i+ }
  ]  t8 E6 A. m" T7 U

& }" y7 u+ h! D6 H, n  ;; give the turtles an initial speed
, O2 L; n4 e# s# V1 g, h7 o  ask turtles [ set-car-speed ]! T( d* A) f- y- n: d* a3 S
- @4 Z5 `, i7 d3 X) W. o) J9 i
  reset-ticks2 y: }0 r) @% t- I7 r1 d8 ?
end- ~6 Q/ R* y& r2 q
/ i: y: ^5 n; E! }" B6 W9 t' X
;; Initialize the global variables to appropriate values5 q- ?0 `2 u0 e
to setup-globals
) t9 V6 \6 Z/ t  set current-light nobody ;; just for now, since there are no lights yet/ g' }- U* {; g: N
  set phase 0
; B! Q( x1 u& x7 M! p  set num-cars-stopped 0
- n& }: `) F) [6 G. ?( y  set grid-x-inc world-width / grid-size-x. o; v0 H' G+ f9 T3 Z' }. q5 ~
  set grid-y-inc world-height / grid-size-y
9 \. e* H/ v2 k% u- _) `! n/ l7 ^1 t( x
  ;; don't make acceleration 0.1 since we could get a rounding error and end up on a patch boundary
. D3 U3 b$ k5 M' \  set acceleration 0.099) k. A: F+ M7 R8 N; O2 ?
end
# o. u0 C2 f% W1 B
. `1 g, n9 i; R  T  D;; Make the patches have appropriate colors, set up the roads and intersections agentsets,
" p! D8 j7 N  p' a: W* ~+ m;; and initialize the traffic lights to one setting
5 `6 y2 }* d: B! e# pto setup-patches7 `6 S8 ?! Z8 }  w  K, S
  ;; initialize the patch-owned variables and color the patches to a base-color9 v$ A6 [5 ?) w; ^
  ask patches
7 O: p; p2 r6 V2 ~) l8 Z  [
: J9 ]0 ^0 k" v# D$ {; a    set intersection? false( c0 N/ R3 ?) o5 X7 P- P( {
    set auto? false7 S3 O- O4 C+ |4 U0 ]
    set green-light-up? true, [0 v4 }2 i8 K5 v$ A4 g
    set my-row -1, G. ^: {6 V" w; d3 V7 ]: U' a6 C: Z
    set my-column -1! O% ]9 ?5 }6 e$ g2 Y% C7 @  K
    set my-phase -17 o& H( w' p9 N/ n
    set pcolor brown + 3
) D7 H0 V5 u0 H& j  ]$ D- w9 y: y4 D7 x
8 p3 k) K" w  @
  ;; initialize the global variables that hold patch agentsets
' a7 R* y' N4 X. s7 q1 b/ S  set roads patches with
8 A2 l% D$ x0 m7 `% `) m4 \. z    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) or
# v- T: ^0 j6 h0 k" \    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]
, y& {0 ~1 r$ e  e% _$ D# o% T! g  set intersections roads with
- r. h( S6 v8 g4 z0 C    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) and! b8 l) q4 o; i$ p: s
    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]" g0 `7 _4 I8 Z+ o/ {

* v+ p) ?5 C# k+ I% E4 J  S/ F  ask roads [ set pcolor white ]
& ]" M: C9 K7 y* b7 @2 x3 f    setup-intersections2 V& @$ F  _; C& L+ @
end! I0 h; a# u: D+ n# W. N
其中定义道路的句子,如下所示,是什么意思啊?
: J/ N" d: A3 U$ \( _ set roads patches with
: K1 j* U! V; W0 V1 k  D( C; c3 X    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) or9 t8 U6 ^: M1 G! h( j
    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]
2 K" Y( A. _( L0 v. }5 N7 V5 m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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