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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。( K  i! B3 {- }/ |) B3 L4 N
netlogo自带的social science--traffic grid这一例子当中,
* R6 d& X( c+ Zglobals
* G3 U, }# T1 ^[
: A- B2 p% v# h. z  grid-x-inc               ;; the amount of patches in between two roads in the x direction7 d: o; w5 f: m1 H& J" k! q+ Y8 P
  grid-y-inc               ;; the amount of patches in between two roads in the y direction
) Y6 I' v1 I# \# r7 W! q) c  acceleration             ;; the constant that controls how much a car speeds up or slows down by if
6 T! B: F  E& y& Y' c2 t                           ;; it is to accelerate or decelerate
7 ?' Y' U3 y# q3 ~  phase                    ;; keeps track of the phase
+ ^) g) \, Q9 |) }/ d' r# x: w  num-cars-stopped         ;; the number of cars that are stopped during a single pass thru the go procedure
* A& u6 w4 z! P/ G3 s" s  current-light            ;; the currently selected light
5 l6 U9 f2 ]+ N: `
" m2 i; V/ w) c) i; S5 S  ;; patch agentsets
# L2 k& F: [. X! c0 C3 g1 O6 }  intersections ;; agentset containing the patches that are intersections
! D1 W! X$ U6 G, s, s. H  e  roads         ;; agentset containing the patches that are roads, D0 T/ s7 K  V$ A/ D) G
]) r& W( e; s4 v# u/ _$ M7 O
/ q9 k, p) t1 ~% p7 M
turtles-own4 f# S2 s: m& i# B
[% L; f* z( M" r! F" q
  speed     ;; the speed of the turtle- R3 M0 p% k' o/ Y
  up-car?   ;; true if the turtle moves downwards and false if it moves to the right
5 l0 B: Y9 ?6 C" L, l) I4 O! X  wait-time ;; the amount of time since the last time a turtle has moved3 F0 Z5 {7 `; g8 c2 A3 `: u- g7 C6 L
]
/ ?7 \0 c: I% W9 V6 f
; m+ i; i. V; ipatches-own
( E. I8 v7 o8 ]4 I) ?' U  r[& a. E7 y  K' o- f, H2 h( }
  intersection?   ;; true if the patch is at the intersection of two roads
2 C. L0 G0 ~' q% E  green-light-up? ;; true if the green light is above the intersection.  otherwise, false.2 S  l, `: V% W1 p( r
                  ;; false for a non-intersection patches.: u6 o+ a, r2 M# j0 N! V
  my-row          ;; the row of the intersection counting from the upper left corner of the- p, Z) T# `" c9 ~3 p( ^
                  ;; world.  -1 for non-intersection patches.& {; u* X. Q6 f) y! P' x1 r
  my-column       ;; the column of the intersection counting from the upper left corner of the
3 W% c$ J- K8 i) p                  ;; world.  -1 for non-intersection patches.+ ]  j+ t- }/ q! N6 a! L- \% v2 K0 u
  my-phase        ;; the phase for the intersection.  -1 for non-intersection patches.
! `* G9 B% H  t7 t4 |+ O- |8 m  Z  auto?           ;; whether or not this intersection will switch automatically.
3 A5 k+ F0 S/ l+ j5 s# r0 F8 {                  ;; false for non-intersection patches.3 H# E' J; t% F
]
2 ]0 g& r3 t: R  I' M7 r- E7 B: K4 Z& k1 H& c
# k) Z1 F. t0 n( J8 m
;;;;;;;;;;;;;;;;;;;;;;
$ d* d4 N3 d" y" E; P- [: b  h;; Setup Procedures ;;
" T/ |5 F  U2 F: O;;;;;;;;;;;;;;;;;;;;;;
5 P4 n  |; W! Z, D/ P
) a3 l4 |) ]' ]5 b3 x6 A$ Z* ^;; Initialize the display by giving the global and patch variables initial values.$ D. I/ h* j4 T( s/ L4 y1 r9 c
;; Create num-cars of turtles if there are enough road patches for one turtle to
1 ]1 I2 d9 {3 H6 L;; be created per road patch. Set up the plots.5 Y5 G- B+ c( [" N& [- s
to setup0 L( |% f3 y9 ^/ q. E
  ca) p- m# p, {4 F) T) J: u
  setup-globals+ }' m8 K% H$ }: S$ }4 @5 ^

) B: ?, c9 T/ y4 `/ v  ;; First we ask the patches to draw themselves and set up a few variables
0 t5 I9 r' p3 N3 L' g! W( T  setup-patches5 a' c  ^9 q- Y8 l6 n. R1 v
  make-current one-of intersections. Q( j9 d* I# I& o
  label-current; {" S' r/ ^0 |* X0 ]
# F3 C# j8 a- ]) n( j6 L5 r# X
  set-default-shape turtles "car"
  Y3 N9 ^7 S% q. r& I' B* Q1 @* G5 ?6 y; y2 h3 T
  if (num-cars > count roads)
* C9 @+ O" L( u. e: _) P  [8 G6 x  }4 k/ \4 T% B3 O9 g! Y+ \
    user-message (word "There are too many cars for the amount of "2 R" ^( H1 G% F; M. v( A
                       "road.  Either increase the amount of roads "
, v: L, i2 ^  M9 S% ]                       "by increasing the GRID-SIZE-X or "" a8 _6 l8 U6 z
                       "GRID-SIZE-Y sliders, or decrease the "5 z* T( w- c$ s  ^& S
                       "number of cars by lowering the NUMBER slider.\n"! M. z: `- Y0 A
                       "The setup has stopped.")% z7 ~, N6 {& O( E6 c
    stop" Q+ Z- n/ F& k- Q) ]; i# [
  ]3 r# w" \. q9 P' F8 N

; C3 D9 i5 P7 u2 y( r9 z0 O  ;; Now create the turtles and have each created turtle call the functions setup-cars and set-car-color
6 E! ?, L0 P, L' [; E  crt num-cars
2 I6 S$ x% L. q8 D  Z: ], J8 y  [9 b# A- T% G8 K8 ?
    setup-cars5 w2 m3 S1 r/ S. |% [5 v  `$ P
    set-car-color
! ~$ v+ d: v0 ?0 }    record-data
! k0 c/ y3 m7 Y' p, `- [4 M  ]: q$ y! Y  \- s9 J
8 k% L1 ]1 p% h+ N
  ;; give the turtles an initial speed
' b- H# o+ k. f# l0 Q- L  ask turtles [ set-car-speed ]2 J# q8 a& G$ B( M
4 \6 c% `  J/ f- w
  reset-ticks
$ [& a+ T# @6 P8 u- R+ M: ^end
# p* h* p# V" _5 {: u6 ~
: i+ f$ Z4 H0 Q) U8 a;; Initialize the global variables to appropriate values5 D/ K  I! [/ M& B7 h8 O% Z
to setup-globals4 u; W% v7 a" G8 N! j) c% V
  set current-light nobody ;; just for now, since there are no lights yet
7 P0 E% U+ o9 U$ C2 O' ], Z) h- ]  set phase 08 W4 ]2 x! e( t: g1 \6 A
  set num-cars-stopped 01 k6 h. ]5 e) }- m/ W2 a' ~+ k
  set grid-x-inc world-width / grid-size-x; {+ q% `) A6 l* C0 y
  set grid-y-inc world-height / grid-size-y
- n, o- [% p7 N6 {5 B
* G3 `' p5 w* k7 e  ;; don't make acceleration 0.1 since we could get a rounding error and end up on a patch boundary
  T/ Z; B* U4 J' E0 ~8 H+ a  set acceleration 0.099
) F& T) k1 P6 O" Y- |' Cend
# s- e# x" i$ r% d3 u( j8 E5 j  P* }- ^/ m8 O2 W% y
;; Make the patches have appropriate colors, set up the roads and intersections agentsets,2 Z& r2 Y) t. u' C7 G) [2 P' A
;; and initialize the traffic lights to one setting1 l- l7 P9 R$ k" n
to setup-patches% p, i6 h' [% i+ D3 F2 p
  ;; initialize the patch-owned variables and color the patches to a base-color* v9 I4 {# M6 p3 _7 a
  ask patches
& a/ ]0 M' A7 z  }3 C4 E) @  [( W; F% y& t* M2 _1 ^7 d+ r
    set intersection? false
: K2 K5 M' `$ \: d    set auto? false
& u7 A. x9 k: u    set green-light-up? true
4 J0 S8 f* q( E3 ]  A    set my-row -1. G: D& D2 J& l9 ~+ h
    set my-column -1
! W8 T$ Y) ?4 R  k    set my-phase -1
7 Y  B: }3 Z7 y    set pcolor brown + 3
9 Y4 _6 J# i; Z4 B  ]5 G0 s4 y- `0 p. M6 S" F

6 M: k" V! U" k9 s4 \  ;; initialize the global variables that hold patch agentsets. X8 G/ r/ x6 ^3 b3 g( _
  set roads patches with5 Q" L6 s$ [7 z# X2 p8 U7 [, k
    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) or
5 q' g1 j" e- D& {$ W  g/ h. |    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]$ ]5 [& D/ ]6 B
  set intersections roads with4 A' `& ?( k% Q2 W$ X) r3 {
    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) and1 u. R6 i9 \1 \; |8 C
    (floor((pycor + max-pycor) mod grid-y-inc) = 0)], ]# @) m' b1 L6 Y$ q. P

  P9 H6 X  v1 `+ Z/ G  ask roads [ set pcolor white ]
0 E  j# L2 T: R0 J) @) w    setup-intersections: g! T3 t% L& |$ J5 {; c
end/ M0 C! |5 B. F
其中定义道路的句子,如下所示,是什么意思啊?
( O2 Y% Q3 S8 Q/ h set roads patches with9 a3 [# S- m, l7 G8 s
    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) or  x- m& i; x7 w0 V' D5 s
    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]
+ j  U8 }) \6 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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