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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。
( T5 V5 [; W! g7 W* s* }9 ynetlogo自带的social science--traffic grid这一例子当中,+ a9 o$ F- Z, y7 Y# N
globals2 n. ]" [" J4 \! a0 }4 y
[( X+ u, j2 t8 w6 s! H3 _
  grid-x-inc               ;; the amount of patches in between two roads in the x direction
9 n! L7 R# [* C1 }8 `  grid-y-inc               ;; the amount of patches in between two roads in the y direction
. I+ z* t" ]: \+ |3 Y# V  acceleration             ;; the constant that controls how much a car speeds up or slows down by if
" Z$ k4 y1 f- f0 d: ~$ D! M' Q9 N                           ;; it is to accelerate or decelerate# D) N7 ?4 z- S0 J' C
  phase                    ;; keeps track of the phase
5 [# k) O4 ?9 ?  num-cars-stopped         ;; the number of cars that are stopped during a single pass thru the go procedure5 f5 q; v5 A! r& ^9 [3 e# B6 Y
  current-light            ;; the currently selected light
! M& z! b0 f! \  {) d
, v' D# }4 X& ^" `8 |$ P  ;; patch agentsets- s4 [: q7 _* X7 K( Q. Q' {9 ~
  intersections ;; agentset containing the patches that are intersections
+ n/ X2 F) n) [3 T' J  roads         ;; agentset containing the patches that are roads
3 Q! Q) e- g5 R; D, {7 w- _]4 m# `$ v  A. S$ r

: N& B. P' n: y: P/ Q6 X3 X* aturtles-own+ P3 {6 C1 U6 @2 k' p4 c4 h
[
0 t/ r$ l# Q2 h" S6 x1 [  speed     ;; the speed of the turtle1 @' J; M0 @' Q) s) B3 ?! k( L
  up-car?   ;; true if the turtle moves downwards and false if it moves to the right
* A6 b, l: g) n6 }  wait-time ;; the amount of time since the last time a turtle has moved3 S: }: u" |! I* B% i
]$ r/ m1 `4 x  a! U, ^( N

+ y0 O/ }3 I+ z6 J9 Kpatches-own
1 V# }$ a! a3 s- R' |  s[5 s: z, [& K, J  `  ~
  intersection?   ;; true if the patch is at the intersection of two roads
' }; ?! ~' r4 r  green-light-up? ;; true if the green light is above the intersection.  otherwise, false.
# u5 |  S+ j- D                  ;; false for a non-intersection patches.
7 g& L  |2 g8 P( X7 s- j/ t0 P$ y% q  my-row          ;; the row of the intersection counting from the upper left corner of the7 a6 e' O* n  ?2 p
                  ;; world.  -1 for non-intersection patches.
% C( P/ q) f6 `1 m1 s! V1 a+ c  my-column       ;; the column of the intersection counting from the upper left corner of the
( A% m/ v3 ^* U( B2 B) Y% F/ e9 p                  ;; world.  -1 for non-intersection patches.
7 _: Z; B5 @4 S4 e, ^  my-phase        ;; the phase for the intersection.  -1 for non-intersection patches.% w7 u/ p, V6 [# F9 N
  auto?           ;; whether or not this intersection will switch automatically.
& v+ v2 O) {! f                  ;; false for non-intersection patches.
, H8 n, K+ m$ @3 o0 E0 z1 T& q( t]
( f) i# m- s; `, o* ?. X; b5 \/ i2 j8 \: q% m8 G

( F# I. `% j; o0 h. g3 ~3 Z0 E( i;;;;;;;;;;;;;;;;;;;;;;
1 `2 Q$ p! S; u, U" U. b;; Setup Procedures ;;0 b  x7 O+ X( u' J; n; ~, s8 T
;;;;;;;;;;;;;;;;;;;;;;6 u% x  |7 v. }2 W' A

9 H% c0 ^0 ^- H;; Initialize the display by giving the global and patch variables initial values.
. s1 r9 b! ]  u3 I+ ?, ?9 M2 d( q;; Create num-cars of turtles if there are enough road patches for one turtle to9 p% a  c1 n) g1 n8 N5 r# {( c& H
;; be created per road patch. Set up the plots.
! N/ O9 [) E1 Y4 w2 u2 ?# \0 e6 Dto setup
6 U2 @" Q. }9 Y+ t) o  ca# n9 ]2 l2 s1 J
  setup-globals
/ K. f! [* r0 m" _7 k6 y8 \  r" {/ ~1 E
  ;; First we ask the patches to draw themselves and set up a few variables2 [/ B5 V7 _6 i5 B/ }
  setup-patches
, N4 ~- `5 ~; k8 {) n  make-current one-of intersections! U% v# ]4 \$ k( S/ i  A* H& P- q# v
  label-current0 s' I% O7 a& c$ r& U6 f
* z, n9 {. m3 Y
  set-default-shape turtles "car"
+ c, n' i1 c6 G& r& n2 g3 |( M
. h0 a3 l  W5 E& e  if (num-cars > count roads)
- v' C/ w( P; H* W  [- b( C" ~/ b$ H; f3 H8 m! n5 v
    user-message (word "There are too many cars for the amount of "
+ D0 D) Z8 b2 I/ }                       "road.  Either increase the amount of roads "
2 \  e5 b: O1 r, Z7 l5 t1 r! l3 S                       "by increasing the GRID-SIZE-X or "8 a7 S' |4 F# r* C
                       "GRID-SIZE-Y sliders, or decrease the "
- x; \0 Z( F/ F                       "number of cars by lowering the NUMBER slider.\n"
& E" z# T  U7 G                       "The setup has stopped.")
4 w2 R) h3 K$ \& a. Y2 ?    stop
6 ?3 t2 J8 f$ E% Q' {. u! S. q  ]( H' c( a; H3 Q# s6 H# F

) J2 G9 ?1 b6 j+ r, r  ;; Now create the turtles and have each created turtle call the functions setup-cars and set-car-color: Q7 k& V: U1 f& M
  crt num-cars& {0 ~- K6 O1 t/ ^) w
  [
1 u, G" r" R/ \$ N( U0 j    setup-cars
: L) D- J. G6 a: G    set-car-color
/ [# L- E) S+ L. G$ [    record-data
! ]5 a  \# f% [, y) S" M  ]
8 L! p7 i- k+ h7 H0 W
( B% f0 p6 H: {% Q5 e8 M  ;; give the turtles an initial speed" |; k. L+ V% r4 r
  ask turtles [ set-car-speed ]
* b6 \4 K7 f4 s; Y5 j( H; p1 t3 q4 N" Z
  reset-ticks; \+ k( ^/ L% F/ l
end/ e5 L0 i8 {! e. V" y$ L+ ~  i4 O

. y( p+ K! a0 `;; Initialize the global variables to appropriate values: v) K4 v5 F7 K: U" Q& T
to setup-globals
6 {- |4 G6 G) o* ~! u3 E2 i  set current-light nobody ;; just for now, since there are no lights yet
2 R/ }5 ^5 O( ?5 o/ S( b' W+ H  set phase 0
% M7 O* |! P+ E( M, O! T0 B  set num-cars-stopped 0
7 z/ [/ b. n/ P* N1 t7 S! p  set grid-x-inc world-width / grid-size-x
3 E  @/ W* i, ~6 c+ d& k% k) A1 u  set grid-y-inc world-height / grid-size-y2 P2 P' s1 P) e" c

& T( M- H* @* x4 o/ [# `3 r  ;; don't make acceleration 0.1 since we could get a rounding error and end up on a patch boundary$ b' Q. s- L0 M5 e+ b
  set acceleration 0.099
+ \! J- d# a- q% o" w/ a; Mend
3 N) {+ x- `, j8 r( y- D4 s3 H# I& D4 A3 Q5 t
;; Make the patches have appropriate colors, set up the roads and intersections agentsets,3 ^( D! e/ M) {4 k
;; and initialize the traffic lights to one setting
4 S- m* u& z6 V4 G+ yto setup-patches
7 D( \' T2 v% I# o: B  ;; initialize the patch-owned variables and color the patches to a base-color
& h. ]! E5 }8 t7 w8 w6 i& N" W  ask patches
. w( U2 e: s" A3 i# N  [7 q: \# ?8 b1 k5 ?  A
    set intersection? false
! Z; K& _3 t, E1 Z% B( z    set auto? false  g. `& O9 ^( r! S
    set green-light-up? true7 ]( O! R4 e2 |: e( }' g
    set my-row -1
3 n0 Z- I0 V* f    set my-column -1' z+ J! P% V9 i8 F
    set my-phase -1
2 W4 [, l6 W% n. x' ?3 [    set pcolor brown + 3
2 V2 l2 z: X+ m  ]
. S2 g% h5 U4 Q$ w' h8 B, ]. ^% v* b
  ;; initialize the global variables that hold patch agentsets
8 M* ^! p# `, Z  x8 e+ e2 Y/ N  set roads patches with/ {) B$ Y4 H% {' P
    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) or
+ D  M3 `7 V, y) L! T0 _    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]
4 n! I& a4 ~  M. H  _8 I  set intersections roads with
' K6 c7 T9 {; e! N( w3 Z/ A    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) and
6 _3 n2 s) ]" m6 W: i' J    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]
5 i$ F7 V9 T1 D! E9 d0 S" {* g2 z/ r" Q0 s8 Y8 F3 N
  ask roads [ set pcolor white ]/ W7 G+ I( Y- C0 x3 j* `, T
    setup-intersections
0 F$ x; o5 W& I, D: @) V/ J/ V! P1 Nend6 d7 S+ w* ?9 ]) C+ k2 X" v
其中定义道路的句子,如下所示,是什么意思啊?  c# I8 `7 k$ z; ]0 B( X* ~
set roads patches with- e" L. g) {% L& E9 X" @
    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) or
! C$ a2 O; D; ]2 f' r    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]
8 [4 w) e  x* i8 @, H4 P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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