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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。
3 N8 J0 o$ A5 J. y# P0 M% ^netlogo自带的social science--traffic grid这一例子当中,
' `1 m% f7 K6 s% B9 O# Nglobals# L8 @) P' f; A  B" {! m
[/ h9 O- O; T( n: M: t
  grid-x-inc               ;; the amount of patches in between two roads in the x direction
5 Z8 I- q1 U6 g, q$ R$ \  grid-y-inc               ;; the amount of patches in between two roads in the y direction0 U8 g7 X6 Z: C8 V6 S9 }: S# a$ m, [
  acceleration             ;; the constant that controls how much a car speeds up or slows down by if1 a: |$ I  U, {# _2 o+ ?; B
                           ;; it is to accelerate or decelerate
% e5 [6 Q  v/ k  phase                    ;; keeps track of the phase9 f! D0 f9 s# q5 P! ?
  num-cars-stopped         ;; the number of cars that are stopped during a single pass thru the go procedure0 P. J! L! Y# n  \
  current-light            ;; the currently selected light
+ O+ |. P/ o+ U$ H
* R& |( {) E- M8 G- H  ;; patch agentsets
/ G: n. b! n& R' ^  intersections ;; agentset containing the patches that are intersections
5 q# [! ~. b8 I6 _6 J) G" T  roads         ;; agentset containing the patches that are roads4 F( W, C7 m- D0 r3 o5 E1 f5 n1 Y
]7 \, H4 a' x' f2 d- {
8 O2 Z$ ]! g0 j3 D5 J9 Q
turtles-own
* D0 d" m2 T% h0 ][
- Z# [1 q( N) U  r; E  speed     ;; the speed of the turtle
* C6 O2 ]& {. e* X, v( O  up-car?   ;; true if the turtle moves downwards and false if it moves to the right4 x+ b# c4 L1 C8 B( O
  wait-time ;; the amount of time since the last time a turtle has moved' j1 }( z- o% P; \% s
]! ~, r* c+ q/ t5 ~) S$ [

6 D- e1 {$ E6 h5 Q- Vpatches-own
9 K+ d) X( B; x[/ |: f! h" k8 ^6 T9 i# q8 _
  intersection?   ;; true if the patch is at the intersection of two roads
3 b6 J- w* |0 L" r  green-light-up? ;; true if the green light is above the intersection.  otherwise, false.
& J; d; a& n& N# c  }5 {                  ;; false for a non-intersection patches.
7 P+ c0 P8 O% d% _3 r  my-row          ;; the row of the intersection counting from the upper left corner of the: }) h4 q$ B) g/ i+ k% z: a. U+ W
                  ;; world.  -1 for non-intersection patches.
; ?) {! Y# q6 T/ e+ F3 @  my-column       ;; the column of the intersection counting from the upper left corner of the/ c8 ^, w' Z1 C- }  Q4 ~
                  ;; world.  -1 for non-intersection patches.2 T  k% R5 J2 f- E. b
  my-phase        ;; the phase for the intersection.  -1 for non-intersection patches.
% @1 e6 n- ?6 y6 b  auto?           ;; whether or not this intersection will switch automatically./ b0 m" W# U% ^! _+ e5 S
                  ;; false for non-intersection patches.
! I3 M' a0 ]8 c  P]2 ]% A2 \3 D! N* u! L
( B% L' w  U1 f3 O% K3 L* u
$ |! L% P4 v2 R1 m
;;;;;;;;;;;;;;;;;;;;;;6 i' {6 j/ ]. Q+ v9 O* \9 _
;; Setup Procedures ;;2 C% y+ H+ V+ }+ ?. f2 j& Q
;;;;;;;;;;;;;;;;;;;;;;
% c5 n, O" D# H# M1 U( ]: t0 r3 D3 x4 A6 z4 ]8 y
;; Initialize the display by giving the global and patch variables initial values.! `, J# d- ]3 d
;; Create num-cars of turtles if there are enough road patches for one turtle to/ W2 m* J5 v3 a( U, `2 ~& \2 L
;; be created per road patch. Set up the plots.
9 `7 y0 g/ I& A$ S- O2 Cto setup. G' }/ K8 D& {% k9 D. M! M
  ca
' f3 ?7 p9 f  [2 f. l  _  setup-globals
' Y6 ?+ v3 ]1 i; n1 Z
& p- y/ B- t" Y7 C5 K  ;; First we ask the patches to draw themselves and set up a few variables& O) x3 _  t% ~# b3 w
  setup-patches
7 o; _! W2 H  Z* L2 H  make-current one-of intersections% A( k. b" U& o7 a( o
  label-current
8 E* {. t- J, i0 e8 @, C& _4 n" I% s, y) k& A+ @/ e
  set-default-shape turtles "car"  D: j7 N/ r; Y2 m

% a5 }( [: E1 D. B0 Y2 [4 ^9 A2 k  if (num-cars > count roads)2 Q. x7 e0 V% @8 t0 s
  [- f3 R- S0 @- o) l. f  J/ z
    user-message (word "There are too many cars for the amount of "
' I5 _+ J" \9 w' F2 a                       "road.  Either increase the amount of roads "
9 p6 E, Q  V) I( S7 p$ E                       "by increasing the GRID-SIZE-X or "
) J0 F( m7 l8 ~8 J0 d! ?/ J                       "GRID-SIZE-Y sliders, or decrease the "
5 N9 a9 G/ D6 r- F! a                       "number of cars by lowering the NUMBER slider.\n"* j6 f8 l* k7 E, e: A
                       "The setup has stopped.")3 Y5 P; P+ m7 }" A0 |  \7 m1 S, [
    stop- Z# ]* c. k( F/ S1 K; f% K- D
  ]
" J0 k1 b2 n$ U- ?* {- g/ f9 Q* u( S' H7 j
  ;; Now create the turtles and have each created turtle call the functions setup-cars and set-car-color' c9 D% s$ {6 w8 S' W' M
  crt num-cars/ X5 ]* J7 ~6 C0 @* z$ T0 n$ j
  [
( x- o3 X' }! I    setup-cars7 K" N+ {& E# g$ z  B+ V4 X
    set-car-color
9 g$ u/ q' m. ~# Z4 |    record-data5 D$ h/ c- i, n6 u: Q
  ]/ ~9 }1 p6 F6 D7 o! v0 V) W$ ?
9 R2 e, n/ b5 T; B" I6 {
  ;; give the turtles an initial speed
: G# a7 W+ J& @7 K; p% t% z  ask turtles [ set-car-speed ]$ U0 Y5 t# k: ?4 G1 o
9 S( F/ r: Y* n' m
  reset-ticks$ {5 a" h+ T4 K. Y1 n
end
; |, N; y4 f0 q1 A9 p$ V( e2 Q
# u& p8 j, \& w3 _9 z3 \;; Initialize the global variables to appropriate values
9 C) ]% V$ ?3 _' E; ?" k, ^" Bto setup-globals7 B3 W7 d8 W3 ]
  set current-light nobody ;; just for now, since there are no lights yet! d" y9 {5 \+ @; g
  set phase 0! ^* a- t+ f2 {. u: n; Z
  set num-cars-stopped 0: I( B5 M9 Z" p/ B' k0 Z' e$ F
  set grid-x-inc world-width / grid-size-x
3 A$ f7 {, H  m* Z0 }- u" W. t  set grid-y-inc world-height / grid-size-y2 [1 T) G  x# V0 g: a
  E; U" _" p' D2 [# Q( r- U
  ;; don't make acceleration 0.1 since we could get a rounding error and end up on a patch boundary
" A3 D' p) f0 Z! c" W  k  set acceleration 0.099) k/ G8 h% @0 U2 A( k7 y' E
end
* c- ^8 y  M! l- W+ W
3 Y5 i8 K1 [* z4 t- v;; Make the patches have appropriate colors, set up the roads and intersections agentsets,
) O( a  _: C1 f6 K) L' q, c;; and initialize the traffic lights to one setting* u( a# p* S1 y/ b2 u
to setup-patches: @) T2 |' R2 ]
  ;; initialize the patch-owned variables and color the patches to a base-color
8 ^4 v* g( D( M! R/ G% a( r" u  ask patches# o' q" r  M! Q/ }) M, Z$ C/ y
  [! D) U6 F( Y( l- s7 Y% C9 i. b
    set intersection? false( E# R. {* W/ p. A% e5 ~
    set auto? false
; Y0 F2 d% d& G5 J4 b    set green-light-up? true4 q/ S  {! |! F. m& W
    set my-row -12 n# |" a+ e! w% l. L
    set my-column -11 X, L$ z- j4 i
    set my-phase -1
7 B4 Q8 h1 Q0 |# m$ ~1 J' Z& |    set pcolor brown + 3( ?# ]6 D. s0 @: Q, @
  ]
5 n3 H. ]& l' W, P
7 D8 Y" u. k" `9 H  ;; initialize the global variables that hold patch agentsets
% ~& b8 _8 k3 Y& M  set roads patches with
8 {- [+ B# O7 F# Q    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) or
0 X7 V7 l% M( q    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]- U. t) u: N2 V- j+ r* z% M
  set intersections roads with
' |( Q- J: O, Z" ?% C1 v+ K) q    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) and
& ]; m) P' ?: [0 s6 P$ h0 m    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]
; h. H- M2 K, S  w( h/ r9 ^
2 o% m+ U& k7 Y- s  ask roads [ set pcolor white ]
$ F7 a9 X. X+ U( i; m    setup-intersections5 C% P# @; ~, e, o
end
6 G$ C6 }5 c) o0 B& F, X其中定义道路的句子,如下所示,是什么意思啊?0 H" z2 W/ l, D; s- l/ U
set roads patches with
( [2 J  z% ], u# Y' b4 ?) J    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) or
0 e; S+ N; v; g  y1 P    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]
1 @! D) O: ~+ f) |4 H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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