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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 y8 N* m1 `
netlogo自带的social science--traffic grid这一例子当中,
6 `0 y/ b' }& rglobals
  f8 b* T2 a' L( y' I! X" c[
8 x* o  `/ E5 @7 X/ @( @' F% ]2 J  grid-x-inc               ;; the amount of patches in between two roads in the x direction
) W8 W; h" W5 g, o1 @  grid-y-inc               ;; the amount of patches in between two roads in the y direction
. J) p$ Y9 ^+ Y7 [; ~  acceleration             ;; the constant that controls how much a car speeds up or slows down by if
5 Z$ _% W' s8 S' T9 V, U' q                           ;; it is to accelerate or decelerate
7 a2 O8 k5 y% x* ~( ~1 x0 Y* ~  phase                    ;; keeps track of the phase
( O: a8 u( W# O1 H: Z  {  num-cars-stopped         ;; the number of cars that are stopped during a single pass thru the go procedure
  s9 X0 E/ J/ a) U, [  current-light            ;; the currently selected light
* H$ W& a7 X: N) `
" d, E5 x8 i' H7 c0 O  ;; patch agentsets
, {  T2 ^; F+ i3 {  intersections ;; agentset containing the patches that are intersections
4 S9 y  t, |( \  roads         ;; agentset containing the patches that are roads
: m8 p6 ~3 g' y, H* X/ ]+ G, T]+ w2 y+ y7 b  R3 @

* n- E" b! W! z% k+ sturtles-own$ }; f/ `2 e" d( ~* H
[4 ]; U* O: H/ a( S9 b* G$ w
  speed     ;; the speed of the turtle0 l* Y! E' U; B
  up-car?   ;; true if the turtle moves downwards and false if it moves to the right7 d" X6 {( ]( S0 M2 L; e) {
  wait-time ;; the amount of time since the last time a turtle has moved
6 k4 e; M! ]2 e; K]
3 V- W9 L' t$ h8 m- D4 E+ R1 Q; R% o+ }# b4 y. y
patches-own
1 h; Y2 l# q$ d5 A0 p) d( F6 n7 b[
1 @4 o% `# I% ]$ s# S1 G  intersection?   ;; true if the patch is at the intersection of two roads
. ?9 D1 W# E% C+ K7 M( y4 k$ g  green-light-up? ;; true if the green light is above the intersection.  otherwise, false.
& B$ i% p" K9 B6 Z( ]                  ;; false for a non-intersection patches.2 r2 F& [0 `7 ?- l1 z, A3 ~; R
  my-row          ;; the row of the intersection counting from the upper left corner of the/ ?+ Q- W3 X9 Z4 T# H
                  ;; world.  -1 for non-intersection patches.% y" K# N  H& `, s0 z
  my-column       ;; the column of the intersection counting from the upper left corner of the
! U2 q9 N0 m( K: H; t                  ;; world.  -1 for non-intersection patches.
( m5 e& ]: E& n4 P, c; S- r  my-phase        ;; the phase for the intersection.  -1 for non-intersection patches.& y) V6 Z( u5 |! g7 @. g
  auto?           ;; whether or not this intersection will switch automatically.
8 j, S5 C3 \4 m4 d                  ;; false for non-intersection patches.
  p* i* Y9 A9 ]0 v]5 W5 q$ \" u( W
( w3 t9 {# c0 q+ `

3 R( U8 v& J% b. U5 C2 n0 X, L;;;;;;;;;;;;;;;;;;;;;;; x# D' e1 u/ z3 d, _4 z
;; Setup Procedures ;;1 ^8 Y. r0 ?+ \/ v0 k; B5 R. J
;;;;;;;;;;;;;;;;;;;;;;; O4 f( c# T; @( \! w6 }

# ]5 h/ `0 M. e$ m- R% Q;; Initialize the display by giving the global and patch variables initial values.
& n/ |4 B0 K# K1 n0 v; N;; Create num-cars of turtles if there are enough road patches for one turtle to4 {) A9 S. Y' P7 b& E8 N
;; be created per road patch. Set up the plots.
6 U  R; v$ h% x. C8 V6 Pto setup7 D+ ~  y; n, v( M) I2 @, }. o' i
  ca3 z  N. Q  S5 |/ P8 w1 a3 e
  setup-globals$ {+ ?2 ~9 N0 J; H  t' c2 j( ^

4 c8 }9 i/ X6 O+ @3 O  ;; First we ask the patches to draw themselves and set up a few variables+ v. w, C' C; c1 \8 Y2 C
  setup-patches$ ~- s: `2 X/ G# F5 F6 t
  make-current one-of intersections
; x/ X1 I3 m, w, D  label-current
3 V! ?! R1 t2 V) A8 h
0 l2 C$ A0 ~( X2 [& r  set-default-shape turtles "car"
% C5 o. p' I& ]0 }& L  g4 V# f9 l  r
! y. S3 z7 G0 I! l$ @& }6 ~  if (num-cars > count roads)
3 Y9 B5 Q& k! C. I8 V3 r7 L* ^  [8 M+ D9 l9 M8 Y: u/ ?9 {' Q" \, w
    user-message (word "There are too many cars for the amount of "
! K+ C  H: o5 e# x5 E                       "road.  Either increase the amount of roads "$ {- i. }" w* I5 f( Z/ N. t
                       "by increasing the GRID-SIZE-X or "
5 U. F: I( b0 i. i6 m* r                       "GRID-SIZE-Y sliders, or decrease the "
! o! b. \( u+ w* g4 W6 b                       "number of cars by lowering the NUMBER slider.\n"! t: U6 B  U0 a1 O7 w( }
                       "The setup has stopped.")& I$ o9 D' }( N  w4 W: F
    stop  \7 Z/ u' k( v3 k$ i5 U5 V
  ]; ^+ y6 l6 f, C3 }% M: @
5 a: l( C- M! s: }
  ;; Now create the turtles and have each created turtle call the functions setup-cars and set-car-color
. v+ p( ~8 ~6 {! I1 y+ R" @% ^  crt num-cars
* C4 a7 c) E: x, v  A  [5 A4 t$ d; z. z, x
    setup-cars" [" {, k- s% x
    set-car-color
+ ~1 G' o, Z$ b+ s* O    record-data
8 m( q! M; H& a4 d* U3 t  ]. |" }* Y& }9 P2 ^+ Z. N- m+ d

. k# H; H: K8 Y+ h  ;; give the turtles an initial speed1 |% \! [- V7 J4 `/ g9 ~/ I3 P
  ask turtles [ set-car-speed ]6 C4 _% l& v( A! ]8 }
; ~. r% q! B* b$ Y: e
  reset-ticks
0 [( m9 D6 J  C' u! A4 Zend$ T" @+ P/ D# V5 M" R4 K

1 f+ N" [9 T8 f;; Initialize the global variables to appropriate values
& n+ s2 G8 g6 Qto setup-globals* ]) @8 C- d9 }3 E5 e
  set current-light nobody ;; just for now, since there are no lights yet
# m; I. H- M1 ^# b2 R  set phase 0
& _3 _7 T( B8 u% I& z  set num-cars-stopped 0
0 j# p$ ?0 C" |+ g  set grid-x-inc world-width / grid-size-x7 d' A/ }3 q4 s5 n/ @9 V
  set grid-y-inc world-height / grid-size-y" s3 b% V1 D# {$ n3 _: A- s$ a* r
1 F% s0 @: f7 u: K0 Z0 c
  ;; don't make acceleration 0.1 since we could get a rounding error and end up on a patch boundary
1 N0 w- i! Z( s" V  set acceleration 0.099+ f3 R9 s! m9 j) q
end
- `% X! v- U8 E: S$ F8 z- \
5 k  e% d% X! W;; Make the patches have appropriate colors, set up the roads and intersections agentsets,
* F% `5 h) X; ]' t. v' K9 M3 M;; and initialize the traffic lights to one setting6 M7 M0 F% c9 G
to setup-patches
9 D/ ^# \8 H0 y# [' A  ;; initialize the patch-owned variables and color the patches to a base-color
% ]0 E1 p* E, [% R4 O, A# n  ask patches
' V. M; q6 E' u: m3 Y  [: h, S( L6 j. A; Z1 I
    set intersection? false# p3 q$ s# ~' ?" F3 U
    set auto? false
' n* O. D* ?, R% x    set green-light-up? true! K7 o3 H) p  u, ~4 u8 |4 L3 \' s5 Q
    set my-row -1
. M0 G: V, q( {9 U3 D! l8 Z/ O    set my-column -1
: D+ Z9 N) X. B, _3 q: z    set my-phase -1
" ^0 I# T" {, F6 Z: g2 M- t    set pcolor brown + 3
& e/ m6 ~1 H( N+ x# B  S6 A& ]  ]
1 b4 G+ D* H8 Q) P$ E  D5 z. F, j! r1 ~$ v- Z) N
  ;; initialize the global variables that hold patch agentsets
# g6 w& ]& ^) Q) G8 n# _1 A) o  set roads patches with5 C! `6 z. l" ?3 u+ @4 }: l  z
    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) or
3 c$ ?) M0 {. T    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]
( z& t$ |& F1 {! o) T# R9 F  set intersections roads with" B3 \$ Q& q. ]4 c- ~" l% J9 U
    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) and
: c6 G& F; v% C  g+ d    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]) |% o: z. L& T7 U; R" ]

- k( G* F, f5 K8 ?0 z* B. A" z  ask roads [ set pcolor white ]
+ U. O: t3 S) @& }' r) ?6 [    setup-intersections
* u; j9 K- L7 `end2 G6 K; W+ v* R' g, N% \  ?4 K
其中定义道路的句子,如下所示,是什么意思啊?
  u' z+ }' ]; N0 W$ \% h" X4 ^4 `1 | set roads patches with
9 K6 F' K, ~, l: a$ t" b    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) or% }4 n. e6 B% r4 M+ l: A
    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]4 e1 B" v% w- D1 \( S5 [
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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