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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。* \, {% Y' u5 p( r
netlogo自带的social science--traffic grid这一例子当中,
' h; o" X4 i! I: G2 `globals+ y+ [/ r0 o* P: ?; \8 L7 Y8 Y$ F
[7 d# J- U+ b) Q6 J7 @
  grid-x-inc               ;; the amount of patches in between two roads in the x direction
, B4 n8 k& `8 H' l$ K+ z  grid-y-inc               ;; the amount of patches in between two roads in the y direction# ]- a  l& M3 L! ^7 C/ d5 k
  acceleration             ;; the constant that controls how much a car speeds up or slows down by if/ \* a' \3 Y$ x& n; B0 j
                           ;; it is to accelerate or decelerate5 E* `1 g1 X# x$ Q/ ~
  phase                    ;; keeps track of the phase
" P0 y: q& e1 M, e9 A% D$ Z  num-cars-stopped         ;; the number of cars that are stopped during a single pass thru the go procedure
/ V1 {( `/ T1 Q+ k  current-light            ;; the currently selected light
& g/ Z" l$ z0 O, J9 E; b4 n0 d5 b
4 ]* y  ?' _  K% |) c- u  ;; patch agentsets. E1 b0 a, Y) l" f  ^
  intersections ;; agentset containing the patches that are intersections
9 o" k, f, d, y. e4 V. [7 A' T  roads         ;; agentset containing the patches that are roads* O6 S7 I  w: G, C( I* W
]. m. X) K& R/ k% s

9 I2 \9 [( _9 c# @' n; ?turtles-own  _9 D8 q! s! D. Q: `
[
3 ~& r2 T, y8 F- T9 s0 ~* C  ^  speed     ;; the speed of the turtle
" C7 m2 n" a1 c0 ^! O  up-car?   ;; true if the turtle moves downwards and false if it moves to the right
$ K& a' W2 j2 X  wait-time ;; the amount of time since the last time a turtle has moved. y8 T' i% B! {5 w/ a0 q
]
0 J# {' M6 M" b+ s4 ?
- o2 [4 o  r: j& F- z" a' ypatches-own
8 _+ S8 m2 Q0 r& ?1 O4 ]9 v[
, d  i8 `4 C" a( w+ ~  intersection?   ;; true if the patch is at the intersection of two roads
5 n8 f- j' j' o$ s9 {, [2 y! H; l  green-light-up? ;; true if the green light is above the intersection.  otherwise, false.4 p% q1 x# W8 c0 [
                  ;; false for a non-intersection patches.& k# ^( W) L# R2 c" b+ G
  my-row          ;; the row of the intersection counting from the upper left corner of the( F6 f8 m  t9 _) I
                  ;; world.  -1 for non-intersection patches.
; x% d. h1 W+ a$ G  r+ D7 P9 J  my-column       ;; the column of the intersection counting from the upper left corner of the
% N  K5 L* L( D- X# X( Y                  ;; world.  -1 for non-intersection patches.0 Y. h) T; Q* G( y* e2 J% x
  my-phase        ;; the phase for the intersection.  -1 for non-intersection patches.
  M( e$ {  M2 O$ }4 p# m; ^  auto?           ;; whether or not this intersection will switch automatically.
& g8 U4 S" x4 }7 {. ]+ P. Y9 ~9 X. X                  ;; false for non-intersection patches.5 {) k5 _4 j% F0 R
]
3 m0 i/ h/ L( W4 e. E% S4 h! {0 n. V+ G& _
% M* ^$ {8 _! c# x2 J  n  I0 F
8 }3 P( g. s0 J& L3 D" B;;;;;;;;;;;;;;;;;;;;;;) R) s/ ]4 y% B& e1 e
;; Setup Procedures ;;: @. f* g6 P9 `" \
;;;;;;;;;;;;;;;;;;;;;;
7 _& i$ G+ E: `9 a8 V$ f) x7 X  S, v" o! P% J9 {& L% A' @
;; Initialize the display by giving the global and patch variables initial values.- H/ R4 x! V% j0 b7 ?) x
;; Create num-cars of turtles if there are enough road patches for one turtle to2 }  V) t, l' {  ^0 X3 K$ i
;; be created per road patch. Set up the plots.2 l* H/ m8 m2 k& t) Y9 }: q2 P
to setup
0 D. T0 {9 X+ c: |  ca9 J* O& z  {7 y. D# d1 U
  setup-globals
5 Y2 }4 g9 U* \1 z# @
: j% j7 q) V) ?) \/ h2 A  ;; First we ask the patches to draw themselves and set up a few variables. n3 V. l0 E7 F
  setup-patches( E- u- F, ]# m) ~, ?5 e, Z+ C
  make-current one-of intersections% \( }* I7 Q1 x  R9 }4 [
  label-current# O1 Z5 s& J! f# R" R0 q0 R2 \
) r/ P# B. ]' {% w$ u6 X! o# a; ]
  set-default-shape turtles "car"
/ f6 c; Y* i5 A$ E3 k2 m  f( D: R/ e, b, T% i/ ^$ L" W) ]
  if (num-cars > count roads)
' }0 L8 n* B9 n+ `$ ]4 Q1 h: i& _  [
1 }7 M" [- d8 u- d    user-message (word "There are too many cars for the amount of "
5 N* ]9 O# v: x2 t- q+ @                       "road.  Either increase the amount of roads "
' M! @2 O3 V1 H( d                       "by increasing the GRID-SIZE-X or ". h. o6 P0 |2 J: t) w* n9 O
                       "GRID-SIZE-Y sliders, or decrease the "
' ?7 y7 M4 W# v+ Y# v4 o: S                       "number of cars by lowering the NUMBER slider.\n"1 H+ G5 V. K# F, L
                       "The setup has stopped.")
5 ~8 O0 F! L( A0 ^( y. Q0 C    stop
+ u" m8 k) r. y8 p) S. H  ]
* C& i) r) X- h" [4 @0 L  D
1 ]9 {9 |0 o8 S, w  ;; Now create the turtles and have each created turtle call the functions setup-cars and set-car-color. s! d1 J- l' R: G) k
  crt num-cars
7 Z  N2 s% L4 e3 X. T& l( f/ f  [# Y8 |! v* K" ^5 z* K
    setup-cars0 x* s, H3 D' b/ S* a2 j" Z+ V
    set-car-color% w; x* Y9 U1 u/ y0 `
    record-data: s, l2 d3 j% d% i# v" m7 u" a, S, m
  ]
4 ]  X5 a: n& t4 c. Z: q; m
0 U; O0 |, w. D0 B  ;; give the turtles an initial speed  ^& W- X; g2 d* x
  ask turtles [ set-car-speed ]
( L! ]9 L# |  C5 ~/ }# L5 i& V- D; C  v6 s, R$ E
  reset-ticks
' Y. K* g6 l: B1 |! o: Hend
) w5 V) W7 e% O7 h
+ Q0 i% l) @3 y) s" t;; Initialize the global variables to appropriate values
2 N0 }* L' `. Z* Z1 Gto setup-globals
+ H; l- D) O# v! p  set current-light nobody ;; just for now, since there are no lights yet
8 W4 j/ H( n- ]' M; j  set phase 0  T/ s# L1 n0 Z! ^
  set num-cars-stopped 0
' o$ |. N+ z* V( _; V  set grid-x-inc world-width / grid-size-x/ m3 J; K1 U$ \# m9 U# `
  set grid-y-inc world-height / grid-size-y) n! U" R7 g/ P

% P0 I" b, {# t; T( ?& J  ;; don't make acceleration 0.1 since we could get a rounding error and end up on a patch boundary
$ [$ h" p, f3 {  set acceleration 0.099
& O% Y+ l  z, c" }9 T) p' \1 E& ]end& K& o/ Q7 R5 P$ _
, E6 J( }7 L6 J# n$ e8 F
;; Make the patches have appropriate colors, set up the roads and intersections agentsets,0 _- _' E  p) Y+ @3 z
;; and initialize the traffic lights to one setting
* W. K4 T8 u' v9 C& Dto setup-patches- n  |" a; K& w8 G/ P  S+ S
  ;; initialize the patch-owned variables and color the patches to a base-color
% O9 b2 p1 ?& w6 E  g8 h( X2 f( s  ask patches+ x& _! q8 |# q, f
  [
/ C4 u5 w. x2 x! d3 ^! I    set intersection? false* E4 G" W; e4 b  n9 C( W2 B
    set auto? false
3 W. P% j5 o* l" C3 m    set green-light-up? true
! O; v" \$ N) R, Q    set my-row -1
" B0 H8 e) f  @    set my-column -1+ m2 @# z4 X9 K5 I1 V8 ^( h) Q( A1 r
    set my-phase -1# \3 H4 v* W4 _2 p
    set pcolor brown + 3
2 m: }! I# `, S  x" f6 s1 d  ]7 O6 O7 e) p( v1 |- d8 r% C+ A

6 a5 p8 g2 z4 b3 [  ;; initialize the global variables that hold patch agentsets% D* u# Y( S0 N. u5 Q
  set roads patches with
" K2 C5 l  V$ \  L5 P1 o  g    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) or
- E; L* B- }% F6 E8 @- b    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]
  F7 S8 G4 T9 l  set intersections roads with
/ |8 `% y) f& ~, B; D6 b6 @5 b    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) and
  D: m3 c  t& S2 m! Z. K    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]5 |( V  T" Y) T! t8 ^6 J

+ u7 n) q! b$ l; a6 E  ask roads [ set pcolor white ]
% g1 V3 }; H5 @& ^* k( L; b    setup-intersections2 W1 y" Y5 V: K9 Y& \$ ^
end
7 r# `+ k4 P& d/ D% S& ~& p其中定义道路的句子,如下所示,是什么意思啊?
3 T* ]$ Y6 V9 m$ e$ W1 O set roads patches with
4 F! t& H: }8 h    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) or
1 Q( Y9 H* L9 j$ Z    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]3 ?7 {0 s9 Y/ M/ |: u  T
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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