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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。$ p; A3 w1 a7 T) t/ M2 o: \
netlogo自带的social science--traffic grid这一例子当中,5 _' ~. z# i) f$ F. n3 {
globals
" k4 m$ G/ k' o2 w) I# \5 c[
3 l) O8 m( L# R/ o  grid-x-inc               ;; the amount of patches in between two roads in the x direction, T+ B, o- \" C5 r, s8 H0 T% _
  grid-y-inc               ;; the amount of patches in between two roads in the y direction
1 u. i  H# m* S9 M% K" }5 Z5 H  acceleration             ;; the constant that controls how much a car speeds up or slows down by if
  W7 K" I; s. L; o                           ;; it is to accelerate or decelerate( v/ [4 \' }; O" V( b& q
  phase                    ;; keeps track of the phase
3 a+ J; L9 V5 h. \0 T0 K( C% ]/ Z/ c  num-cars-stopped         ;; the number of cars that are stopped during a single pass thru the go procedure
& E; A* N1 _# I5 j# k  current-light            ;; the currently selected light
1 i8 ?- C2 P. J1 j8 {4 l6 _* J9 l1 n
  ;; patch agentsets: }1 L9 W( \! `- ?9 @+ Y
  intersections ;; agentset containing the patches that are intersections" s, ?) H# Y+ a7 Q4 y% l
  roads         ;; agentset containing the patches that are roads; Q+ a* W5 F# P
]
/ o8 b. c# [& L3 B4 R# m! C1 a+ X* Z2 u+ [) G. @
turtles-own
& B* j* c) r# C; l4 C  I[( R: y$ s- k3 M8 j
  speed     ;; the speed of the turtle
+ ~2 Y. g9 Y( ^' K$ F  X) N  up-car?   ;; true if the turtle moves downwards and false if it moves to the right
8 s+ c8 g5 c0 Q  wait-time ;; the amount of time since the last time a turtle has moved. o, r; Z! R; l1 ~6 ~( Z9 i& q$ X
]# N4 N. m9 ~! L  Q
: N- V" n# v$ r0 ], g/ x( W
patches-own
5 k, \9 D9 `% \; ^[) I: o3 d* J5 ]- y% x- f" b& m
  intersection?   ;; true if the patch is at the intersection of two roads9 G, H+ D1 R( Q
  green-light-up? ;; true if the green light is above the intersection.  otherwise, false.
3 d$ }- c7 P8 u" w4 n% p                  ;; false for a non-intersection patches.6 k1 Z. q4 y2 i( O
  my-row          ;; the row of the intersection counting from the upper left corner of the4 b6 Z  w$ R! y- S( `- ]
                  ;; world.  -1 for non-intersection patches.9 a' ]: Y) |1 J' K# V! _; j" K
  my-column       ;; the column of the intersection counting from the upper left corner of the4 r) ?. `3 C6 J+ t: g* R, F) |
                  ;; world.  -1 for non-intersection patches." [) }+ X% `$ Q6 f% s& x
  my-phase        ;; the phase for the intersection.  -1 for non-intersection patches.( _1 n) y2 U: O% i
  auto?           ;; whether or not this intersection will switch automatically.- G0 @: q3 b) l5 A; t6 f8 |
                  ;; false for non-intersection patches.
$ D" m5 I: j: H7 V% E]
( h, a4 |2 q3 l# H6 D6 P
; p+ \, s- e1 O- _6 b3 C+ b3 `! i1 {: c, l# t' O9 Z& ~
;;;;;;;;;;;;;;;;;;;;;;, Q, z3 g# x/ t
;; Setup Procedures ;;$ U! |2 J9 Q! L
;;;;;;;;;;;;;;;;;;;;;;
0 s& `% X0 h3 ^" ^2 F7 h) V5 X8 h- T
' c6 g9 u8 u6 t8 _;; Initialize the display by giving the global and patch variables initial values.
  G! t7 o1 L3 {$ L" j# J" Z;; Create num-cars of turtles if there are enough road patches for one turtle to
; s& f8 H) y6 g9 m; u0 i* J8 x. W;; be created per road patch. Set up the plots.8 ^: L4 S: j' W! d
to setup$ G- h7 m- e* C$ B
  ca
0 F  J1 t3 G3 X4 W. h  setup-globals9 B$ u$ u9 X6 }& i/ _

( g: G+ q  a4 ^9 b( O! ?  ;; First we ask the patches to draw themselves and set up a few variables1 I3 X; {9 z; Q+ U6 C
  setup-patches
' h: x* ^, R2 G2 x' `  make-current one-of intersections
4 y& F0 b3 k; I1 T  o  label-current
1 O0 U$ s9 Q5 p; [* r
3 L" S/ \8 J4 M1 |0 i! z  set-default-shape turtles "car"
6 P# ^0 P8 V/ n5 N7 a  Z6 c4 {2 L8 K: e8 Q
  if (num-cars > count roads). A. r4 f& k, I- r8 \7 Z5 k/ ?
  [
* y  a( q/ V" }* B5 _9 F7 B' Z    user-message (word "There are too many cars for the amount of "
& ^: F; \( A2 K! P2 ]                       "road.  Either increase the amount of roads ". m; ?, J6 ]2 a: S. O
                       "by increasing the GRID-SIZE-X or "
$ B" x8 a  C. m8 t) {4 ]+ i4 j                       "GRID-SIZE-Y sliders, or decrease the "
0 r5 ?  s* N/ R& J4 H# @                       "number of cars by lowering the NUMBER slider.\n"1 `% S/ |  c* s3 d& J
                       "The setup has stopped.")3 `5 ?( E2 a8 n$ u6 ~5 |, \6 _5 j
    stop- e+ [- n& p& j) U3 ]8 L
  ]7 F* p- ?% i# D9 G" F

; s' H, Z0 W4 X+ _* e) `  ;; Now create the turtles and have each created turtle call the functions setup-cars and set-car-color
1 I; d( u  p0 O/ J7 t& }  crt num-cars
4 ?# p" l& H; z; W  [4 s: y8 v3 Z6 J# o6 j- U
    setup-cars/ Y; n! n7 Y& R/ G4 z9 ~
    set-car-color% w% f2 ?6 a! Y0 s
    record-data
+ L2 e0 J# t$ i, {1 `  ]
7 }  K; t: ]- p" v3 q
% x# K" L1 Z1 a  |1 q  ;; give the turtles an initial speed0 H6 O' S! T8 O
  ask turtles [ set-car-speed ]6 L% G2 x7 D, y, Q; x

: M) k/ S" D2 Q: w  reset-ticks
4 q4 D; r* d) a5 i- r. Q& Lend
. H- M' k: n: L$ T8 `% H. i. s" W0 }6 ^& a% E9 ?  z# L
;; Initialize the global variables to appropriate values
! x% P5 x+ Z7 k# p4 Bto setup-globals
5 J' d( h, C2 m& d$ h4 R  set current-light nobody ;; just for now, since there are no lights yet$ G) H$ X; q: b' k
  set phase 0
  ~9 s+ z; a1 L* a' a+ f  set num-cars-stopped 0
+ g  M1 @) A4 C1 o& c) W- z# m  set grid-x-inc world-width / grid-size-x
0 v, s. U6 a" J+ S6 B. V  set grid-y-inc world-height / grid-size-y$ D- v: W: S$ F4 I2 o# Z+ ?4 `
' q6 |, A( m; b3 h! c
  ;; don't make acceleration 0.1 since we could get a rounding error and end up on a patch boundary  |& e' \* f+ b  v% Y) K2 Y
  set acceleration 0.0991 v! X; L5 O, E6 C
end+ J. R5 _8 U+ D4 e; u  h
5 A! l' c+ ~( O% D
;; Make the patches have appropriate colors, set up the roads and intersections agentsets,/ B9 X! z) T5 x9 G# h& Q" R
;; and initialize the traffic lights to one setting8 |* O) ]  V% p- o5 Q* e- i7 A4 b$ Y
to setup-patches4 `- g: t1 E0 A/ D: x) U
  ;; initialize the patch-owned variables and color the patches to a base-color2 J7 [' Z  R/ l/ {
  ask patches
6 c0 ]0 C/ k" }& `  T4 o8 q$ c3 g  [6 J2 }" M3 Y$ \6 i5 s- O
    set intersection? false# A+ w; V0 w* j1 _1 n7 B, ^8 i
    set auto? false
# {8 v7 i+ h, x0 Y. A9 `    set green-light-up? true
$ c0 L% q8 Q$ Y9 f3 U  k6 o    set my-row -16 t* ]+ d0 Q" i7 u
    set my-column -1; y+ P$ t! b2 t/ c# D
    set my-phase -1: h' F& a7 j2 Q- d- ^7 `) D6 W$ C
    set pcolor brown + 3
. z0 m; a& E& N+ \2 T" M; m6 _  ]  y2 v9 G- K2 v, i8 y; A
1 Y: s. Z+ h% x" v; y8 K+ L
  ;; initialize the global variables that hold patch agentsets1 A$ L; e  x9 {4 a3 c5 r/ I0 u( \
  set roads patches with
( C9 d6 {7 ?+ D+ Q    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) or% [" O) `" `3 O; l" T1 q  b5 ^% S
    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]
# n- v$ e  H# i5 `, ~. r  set intersections roads with0 |! E$ n/ ?# @% {4 `7 ^" |
    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) and
+ I  x8 [6 [( f4 H& M4 a: q    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]
% P+ H0 V2 n8 B, m! f; G( \9 V" X0 [" W: ]: l
  ask roads [ set pcolor white ]% N5 [# k! A7 R) e
    setup-intersections: w9 \  X) _! G, X
end
* s6 x8 g' S( }# I其中定义道路的句子,如下所示,是什么意思啊?
5 w1 U& h0 F- p4 {1 h  z set roads patches with. t# ]0 g: [+ s& S7 J/ A
    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) or! ]0 [- X2 E9 |+ t+ d' ?
    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]
0 |  T  Q6 I2 r6 ]7 u6 i" p6 O- \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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