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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。6 |$ b' h$ O: F' }, w( r1 ?
netlogo自带的social science--traffic grid这一例子当中,' R0 B2 b4 G( u" k
globals
$ A* C, g  {- N1 ^& T# r[. O# Z# H2 h6 w' W8 B
  grid-x-inc               ;; the amount of patches in between two roads in the x direction
, X% u8 d: N1 [' Z. Y* j9 B  grid-y-inc               ;; the amount of patches in between two roads in the y direction2 {% P% ]: L4 q  O
  acceleration             ;; the constant that controls how much a car speeds up or slows down by if0 t: R" L$ F) j0 T, q
                           ;; it is to accelerate or decelerate
1 P0 h5 {. z  w! m  phase                    ;; keeps track of the phase
7 d/ b* p4 t6 k$ e3 j! X- w9 [  num-cars-stopped         ;; the number of cars that are stopped during a single pass thru the go procedure6 s* D7 @4 r$ t; h1 y; O0 c/ g# U$ B
  current-light            ;; the currently selected light
+ u/ ?+ \3 I: y+ z2 _* j  m* B2 h% m9 C
  ;; patch agentsets; e' l: e, J8 I+ c( A' F4 d
  intersections ;; agentset containing the patches that are intersections
2 I# Z. C* m7 \6 _! v  roads         ;; agentset containing the patches that are roads
9 O7 a/ |: D- m5 d1 a. j]
; ?, W# u' I# L1 U
9 y7 o) V) h$ M; pturtles-own" ~! c. u) A9 I) r- _/ V. B
[$ U% c+ j& C* A7 Q) w
  speed     ;; the speed of the turtle
. ?$ @/ z( y" k0 q  up-car?   ;; true if the turtle moves downwards and false if it moves to the right
! j! S: w9 I9 ]  wait-time ;; the amount of time since the last time a turtle has moved' t- p7 d+ K- _
]0 c! S- x  {/ [& G* ^* _
5 O, p, v' }1 g4 J, e
patches-own
$ F% B) Z6 n3 @+ S, b[
' o: M+ ~+ _, ~% y2 M5 z  intersection?   ;; true if the patch is at the intersection of two roads
& S- F2 C- w  }' V3 P4 H  green-light-up? ;; true if the green light is above the intersection.  otherwise, false.6 G& |# k% n( S, ^+ K- F; y
                  ;; false for a non-intersection patches.& L4 G% Y4 ~* O5 ?& ^1 v) A
  my-row          ;; the row of the intersection counting from the upper left corner of the& Q$ u! K! l/ c) y5 C, h0 X
                  ;; world.  -1 for non-intersection patches.2 j% o- k- u0 g$ I" ^( Y- y5 R2 y
  my-column       ;; the column of the intersection counting from the upper left corner of the; P/ n9 W8 }- H
                  ;; world.  -1 for non-intersection patches.
4 \8 n0 J6 ~* R. M% V  my-phase        ;; the phase for the intersection.  -1 for non-intersection patches.
( o: e4 V; i' y6 C- v4 Z; j% n  auto?           ;; whether or not this intersection will switch automatically.# `0 f& n5 C; C0 _
                  ;; false for non-intersection patches.
! ]4 x  d, r1 r: @2 d# r# N0 u3 X]
+ p* K- V$ |* }  h, g. k1 @) q. j7 B" l7 X. ]- _; s+ I5 |
) F$ u- W4 b- x: s+ j1 t- \* [
;;;;;;;;;;;;;;;;;;;;;;
/ [& V5 Q7 w; z+ [% W. u1 P;; Setup Procedures ;;
# }7 Y8 t4 U8 n2 V7 l/ z;;;;;;;;;;;;;;;;;;;;;;
; g3 i; }1 m6 |1 x) t' [$ i( [
;; Initialize the display by giving the global and patch variables initial values.
4 Z1 i' ~; j6 k$ s;; Create num-cars of turtles if there are enough road patches for one turtle to
# I& q4 q, k% h' g! c, p;; be created per road patch. Set up the plots.- h) |6 J4 C$ ~5 @
to setup* i" g3 f9 _8 C
  ca
& X" X. J" x6 f4 L* r  setup-globals
  }* z" n6 R7 Y0 H$ L: f' W' C
% I! ^4 O, O3 ^/ m0 h0 K  ;; First we ask the patches to draw themselves and set up a few variables
% A  y) k9 T  S  U& V$ g5 H  setup-patches9 U4 D# `4 m! S/ q0 [9 g0 x
  make-current one-of intersections/ v8 I# @3 U+ _
  label-current
: N/ Q1 Y& G/ ^+ u4 K8 m* K/ E' \$ a/ h6 E1 }
  set-default-shape turtles "car"
& l' N1 l9 E( C/ g* w3 M* l8 Z6 s2 K3 r* s( s; u+ i
  if (num-cars > count roads)+ Z0 r, @- G, c! B: y  U
  [: ]6 K; b# r! K& M: K
    user-message (word "There are too many cars for the amount of ") s7 l2 _% A% _! t: N( {! H( f
                       "road.  Either increase the amount of roads "
7 }6 Z& B. j3 ^6 q# s" w                       "by increasing the GRID-SIZE-X or "# R5 }/ f1 u" ~0 T' e  H, m+ t
                       "GRID-SIZE-Y sliders, or decrease the "
/ f1 \, R' @0 t- \& {7 k                       "number of cars by lowering the NUMBER slider.\n"
9 U1 B9 Z, P! a3 p% Z- @8 i                       "The setup has stopped.")
9 K" e! z0 d, @  {# W: N" C5 l    stop6 X2 S: Y9 E7 n% r4 H
  ]3 i4 {' E* A: I8 c5 z. L$ }& T

' o9 G# f  O* F' w. r  ;; Now create the turtles and have each created turtle call the functions setup-cars and set-car-color
% J/ g1 z) H; {+ m  crt num-cars9 T0 d2 s( P: Q7 F$ {: i
  [
: C$ p9 j) p& p. X* E6 [6 K% h    setup-cars
0 i, g8 n+ U. i, s( Q8 c0 F, f    set-car-color9 @$ j8 _/ q6 f/ r+ \; W
    record-data0 P7 {+ L' p" J% I8 y9 U
  ]
# Y5 i( u& U# _7 ]3 L, w2 a
# s8 C' B% s1 c2 q- U9 V4 u! v  ;; give the turtles an initial speed
" R$ K, ?4 D* a0 W- D& }  ask turtles [ set-car-speed ]
: o% Y. m5 F2 _+ ~# e- e
7 {+ U2 J  \, l  reset-ticks
3 w( o' `' V& N$ _6 ~9 R7 gend
9 R- v4 q) U8 ?* X# z$ f* ^
* P6 ^1 J8 r6 R/ [$ ^: D0 {;; Initialize the global variables to appropriate values
* F  H: {8 r$ X0 a/ Q& Q3 L- j! bto setup-globals
0 q0 @' L# ^  d. X& @# r  |: W; x  set current-light nobody ;; just for now, since there are no lights yet7 N) w6 p) M& {8 ~2 A5 L/ Q" ~5 i
  set phase 0
/ h8 f# O/ q% j1 g6 _* c% g  set num-cars-stopped 0
  f" M, F8 m! \8 @( D5 V  set grid-x-inc world-width / grid-size-x
1 w( Z. C4 W9 r6 {3 Y4 t! L  set grid-y-inc world-height / grid-size-y
7 ^6 t  L0 s; X; c  @% Y7 L1 \# S
  ;; don't make acceleration 0.1 since we could get a rounding error and end up on a patch boundary0 ?! [4 b6 D4 u( w; C9 u  y$ X* w
  set acceleration 0.099
! i2 m" d% f2 l9 n' Fend1 Y7 C- C; ~2 w2 y- _- E* ~6 z

* J: w, z! d' x( ]9 o+ h;; Make the patches have appropriate colors, set up the roads and intersections agentsets,
/ Y! i' k# Z& _# a;; and initialize the traffic lights to one setting( T+ N3 d% ?: k: ^: y* ~2 @
to setup-patches9 Z7 B# |1 e1 t: I
  ;; initialize the patch-owned variables and color the patches to a base-color. _+ T+ q' l0 V# D% o6 L, C
  ask patches) m. O" |. N- U
  [4 T, c) q; m0 {, t& v5 c* {% B4 _; H
    set intersection? false7 c1 L6 ^" N. X- d
    set auto? false) A% m0 X+ q9 r* h  j  q. N
    set green-light-up? true7 ^/ \5 r$ o, W5 l, A! M/ I$ U
    set my-row -1; c' p8 F+ f3 i
    set my-column -1# F' r8 O4 t- F% V
    set my-phase -18 A2 f2 G% K2 G! K: y; n" O; ^8 g
    set pcolor brown + 3
4 R* G& L0 v$ b, s7 a+ _9 Z  ]
+ K! D7 z' V# z! g# C& M+ y4 c+ ^  p8 b5 Z& d9 o* E
  ;; initialize the global variables that hold patch agentsets1 A3 ], h& b! m) A
  set roads patches with
6 m1 N- L( D/ V4 A1 I+ {4 C* O6 C" M    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) or5 [* v7 i) X  f; J0 O# V$ W
    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]$ n* k% l1 j! g7 r
  set intersections roads with5 Z8 r3 P" R3 K8 E' D
    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) and
, s& t% c/ \! B  c    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]
8 a" C, p+ F( g0 v0 J0 {6 I; k$ @8 a; N- L7 d% _
  ask roads [ set pcolor white ]
  T1 P$ |# F3 {' t5 a    setup-intersections* n& D' ~5 L" |( J7 U# \* h5 a
end
9 A4 n+ d3 K7 b其中定义道路的句子,如下所示,是什么意思啊?( L( E0 N$ p/ B! Q
set roads patches with$ {- o! R& c- L5 t" O$ ]' N
    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) or
0 m, q' D2 f. T1 b  _4 b( v+ ~    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]
. j) E. C3 I* V9 b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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