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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。4 Y) q  |# P5 \3 N2 p2 T6 ]' x) R
netlogo自带的social science--traffic grid这一例子当中,
0 f3 @+ N8 V0 B+ H, O# Tglobals
$ m5 E& C' s; O' C% i[6 R, J! I* \0 ^! O1 S& l
  grid-x-inc               ;; the amount of patches in between two roads in the x direction
7 e: q" O0 V% M5 V% m0 U  grid-y-inc               ;; the amount of patches in between two roads in the y direction7 }7 S3 z4 S5 J$ ^4 W3 t6 w
  acceleration             ;; the constant that controls how much a car speeds up or slows down by if
' W1 Q- Y9 @& o                           ;; it is to accelerate or decelerate
* R. Z$ Z) s" K8 X! Y. n  phase                    ;; keeps track of the phase. T7 w9 x7 C% \: s* L0 W
  num-cars-stopped         ;; the number of cars that are stopped during a single pass thru the go procedure8 k+ U3 S" N- r
  current-light            ;; the currently selected light/ \/ A; K' G5 h% k! E' P- a

) U5 @$ S) t2 i" Z& |  ;; patch agentsets1 `$ p9 T8 V+ X* w4 V" u
  intersections ;; agentset containing the patches that are intersections, \! B5 }# x, ~: ?7 L- u: r( b: q4 c
  roads         ;; agentset containing the patches that are roads
, [8 s/ C. T# @7 o( h6 \]
$ |& M4 R* |8 M, j; Y2 ]  ?
; l8 D9 k! G$ y. B0 T: s; O1 h% cturtles-own) N6 ~4 ]! A) h* Q; {, [+ u/ Z. b
[% I3 R+ Z: m; ~& j# u
  speed     ;; the speed of the turtle) x' D& P# V; u, {1 {2 W
  up-car?   ;; true if the turtle moves downwards and false if it moves to the right2 j  U/ F% z/ U) o/ {
  wait-time ;; the amount of time since the last time a turtle has moved
& t' l9 J6 J8 Z& M- k2 y]7 n- Z% }; C4 g- ~9 R3 S% a2 S

; N8 Y! ?( ?+ c6 A. h$ i+ d* k9 xpatches-own
. g/ M. X: S5 N9 i+ N: f% `[
3 f& b  ^9 {, R  intersection?   ;; true if the patch is at the intersection of two roads2 `+ E6 ?  e  I* c( A5 B
  green-light-up? ;; true if the green light is above the intersection.  otherwise, false.; g, W1 n* v3 d  M, ]2 T8 t  M/ l/ P
                  ;; false for a non-intersection patches.9 P; V& _* g$ e% y& K, g! x2 O$ j1 C
  my-row          ;; the row of the intersection counting from the upper left corner of the
+ V# }1 ?5 [) o; F8 r+ y7 y                  ;; world.  -1 for non-intersection patches.: v+ q) o  a/ v
  my-column       ;; the column of the intersection counting from the upper left corner of the  v. ]9 u- q9 h+ @% o$ n7 s! x
                  ;; world.  -1 for non-intersection patches.
1 T5 t9 R: v* m  k( \2 z  my-phase        ;; the phase for the intersection.  -1 for non-intersection patches.
. T* `' e  ?9 `. g, @3 H  auto?           ;; whether or not this intersection will switch automatically.. }* e$ F% r0 l5 o
                  ;; false for non-intersection patches.
: E% W4 s+ R! I9 Q1 R" z" n: |4 ?! M]
; R/ l9 V/ t4 x6 v; L* }$ \% d6 J% \

. k) L6 |! M) e* i9 g: n' I;;;;;;;;;;;;;;;;;;;;;;
- M+ m9 R. I! H4 g- @( e;; Setup Procedures ;;* E0 R+ B, m5 ]
;;;;;;;;;;;;;;;;;;;;;;" Z3 H3 p, E1 t& E' ~* |+ O8 n: a7 C7 [
4 }1 z; o  `% O
;; Initialize the display by giving the global and patch variables initial values.
- i+ _3 F0 L1 l6 q; \+ ?, A;; Create num-cars of turtles if there are enough road patches for one turtle to
" s$ {; l* x$ H) |0 X;; be created per road patch. Set up the plots.4 b# d5 F; L6 s( L2 e
to setup
) K* y# S+ a8 W. ?  ca
! {6 w; ~5 W& u, l7 X  setup-globals/ L6 i2 U" ^+ V9 P3 Q
! @& {: x; S4 r5 E6 t/ l& _
  ;; First we ask the patches to draw themselves and set up a few variables1 @  F2 l& v* b) H  z" h$ l7 F
  setup-patches
- ]% Q; A  O$ E# c- ~" C  s5 s  make-current one-of intersections9 c" y; a* I- ^, Y9 a
  label-current
0 J* J- G4 w& L" t7 y# q
. h0 d  l6 v; u  j0 X6 n6 a: i0 Y  set-default-shape turtles "car"
. V3 y! b" R) F2 h
4 z9 s4 y3 S6 R& q* G& r9 N5 h6 Q! A  if (num-cars > count roads)
9 R0 X/ c2 |8 Z$ M0 v8 q  [) a. s" @' |( J! }( z' M1 h9 g
    user-message (word "There are too many cars for the amount of "
, X! r+ R4 J) o8 f! L) r                       "road.  Either increase the amount of roads "- e, ?3 C- ?: w0 r% x! }: B! ~
                       "by increasing the GRID-SIZE-X or ". p4 E+ {9 R' c" h
                       "GRID-SIZE-Y sliders, or decrease the "
8 b% R& r6 g8 }# T1 q( L0 {3 y, f0 B$ z7 ~                       "number of cars by lowering the NUMBER slider.\n"3 y9 E, ?3 s7 z& o
                       "The setup has stopped.")
& s4 T+ f1 a) Q# N    stop. h& C3 k, r$ m$ f5 U* H1 H
  ]; N5 x' N4 I# Q- a: z2 }

- C, x  N% `9 l# R( h0 u  ;; Now create the turtles and have each created turtle call the functions setup-cars and set-car-color- l  \; L' Y% y: T, \' o8 z4 s
  crt num-cars4 [4 e) Z% q& B, }' }
  [
% Z& Y# A) \7 y) H; G4 G    setup-cars
) [1 x1 F& Q/ @    set-car-color# L" I1 p3 t8 s% V0 P
    record-data
, Z, N7 }3 a6 U0 l1 U5 S  ]- S: L8 u4 e! `6 T, W
3 i( J6 X" `+ ?$ n; m9 C* U' x9 d
  ;; give the turtles an initial speed( \$ l8 K- r+ H( z' {) m
  ask turtles [ set-car-speed ]
" A; M( B) j0 N  A. w8 P
' A% {) c' o4 V  reset-ticks
! I# a* i* e9 [" R; c- N& E& Bend
* m, L3 \/ q- E0 I
; X, \! N9 z+ l. y;; Initialize the global variables to appropriate values+ ?, y" Y) Z+ s( _  c; i/ D
to setup-globals
* O7 g! S+ `3 b  set current-light nobody ;; just for now, since there are no lights yet& J% }: C! I$ C) [; s" p) c) C
  set phase 0/ G8 W) P7 q' s  l: w
  set num-cars-stopped 0. Y( Y1 B% [6 d9 [$ y7 O$ m
  set grid-x-inc world-width / grid-size-x" x* ^; O" G8 H0 y
  set grid-y-inc world-height / grid-size-y$ m+ h& X; w" [7 h! i+ v
" [  n1 F, {/ I: |% j8 G: t" s- N
  ;; don't make acceleration 0.1 since we could get a rounding error and end up on a patch boundary
! P$ h# p  S& K( b0 E- }4 g  set acceleration 0.099
' @! u9 P: N: b! v1 t" ^end, j/ c1 U% i* K# `- A. x
: L5 b' h2 M% x0 |$ L
;; Make the patches have appropriate colors, set up the roads and intersections agentsets,
/ \: [* x( v( k) s& ]$ A- E/ Y9 G;; and initialize the traffic lights to one setting
3 k/ v9 G3 K2 Z( S3 Y6 L/ xto setup-patches
. y$ p, n* X  y  l+ b  ?5 q5 z8 o. a  ;; initialize the patch-owned variables and color the patches to a base-color8 d! F6 `( t. a/ W& \1 }1 R  K
  ask patches
1 d: d( l% O0 o6 @+ r( \/ I, n/ r  [% f) L4 V- l, s. d
    set intersection? false
: M* m1 u1 T7 V% c2 n7 {    set auto? false$ ^6 S: u, R6 i+ }
    set green-light-up? true  W; q  O: `0 I7 o
    set my-row -1
8 ^: ]5 t6 `. Z2 X# b    set my-column -1. J4 ]/ J, d6 s# {4 L
    set my-phase -1
" P6 i8 P7 M' L0 U2 L$ E    set pcolor brown + 3
# r' \& T$ r* N! w  ]
. F5 q; M% P. E( x; p2 P. @/ y/ \( E
  ;; initialize the global variables that hold patch agentsets9 x3 w" s& A4 x7 p  L; e
  set roads patches with5 r9 @3 b: Z7 V0 G
    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) or. b; B$ b8 z$ v  b
    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]- D4 Y9 r) X  r) \( c
  set intersections roads with6 q3 a2 ?, |2 w: {8 q' i
    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) and
5 y- q- |: v$ Q7 z" c* \- M: A5 q    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]8 j, Z2 N3 }& m
; r' q" f8 L0 \
  ask roads [ set pcolor white ]$ n# @4 y. N/ A' X8 r* E' [+ A3 Q6 g/ I- v
    setup-intersections- z, o: g3 P8 ~+ t8 N/ y+ W, e
end
: ]0 u8 n7 z0 G* @* i其中定义道路的句子,如下所示,是什么意思啊?7 L$ N% [' R$ r
set roads patches with, }4 w5 X& u0 z$ j9 I2 J) y
    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) or
5 X% F* T/ V0 M8 c: r. g2 N/ k    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]% W$ T5 W5 c0 F% c1 L/ J
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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