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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。/ R9 e2 q$ K: ?# T- A
netlogo自带的social science--traffic grid这一例子当中,. o9 c: ]& a. `9 o) l4 n1 b9 M+ a
globals
3 y/ {* I& m5 E  E# P4 L7 J) o[5 n- i+ ~2 a+ }5 _+ }
  grid-x-inc               ;; the amount of patches in between two roads in the x direction! }3 F7 S2 K' c1 w7 B$ ]
  grid-y-inc               ;; the amount of patches in between two roads in the y direction; ^8 {6 w$ s7 E3 k# ~
  acceleration             ;; the constant that controls how much a car speeds up or slows down by if$ y7 O! v. Z% ~
                           ;; it is to accelerate or decelerate
' w+ S# R2 A1 C8 _2 c) A6 l  phase                    ;; keeps track of the phase
5 {/ s& Q9 j( r+ ?& n! C: U  o  num-cars-stopped         ;; the number of cars that are stopped during a single pass thru the go procedure) U4 c# |  Z/ i( L6 O) J
  current-light            ;; the currently selected light' s) T  K& _( j0 m
+ |( _8 @$ u8 |$ ]
  ;; patch agentsets
. J: v) ~  f  c2 y+ ?$ g  intersections ;; agentset containing the patches that are intersections" x! v/ ]4 y; l1 ?
  roads         ;; agentset containing the patches that are roads+ C: G; \* N% ~& B+ W0 V3 R& f) S
]
2 N- K+ S; b. u" J* u% E; R% |1 `) i# h- E" |- q, F8 E9 I! Z
turtles-own: ^) J1 w6 [" j+ a
[
9 D5 f6 L& ?8 J. e$ m* D' J  speed     ;; the speed of the turtle
: [( I6 I& \7 }7 i0 e3 ]! B  up-car?   ;; true if the turtle moves downwards and false if it moves to the right) q  P9 P3 C9 P) b8 o$ t) k. v% h
  wait-time ;; the amount of time since the last time a turtle has moved; |7 f+ A8 |6 b. }
], a) f* H+ \  ^5 Z

0 k1 q8 q% [0 Q5 ]8 R$ m+ Gpatches-own* A% w4 K  ^- p% @( b% W% h: K3 [
[
8 Q/ l& I4 }6 H# |  intersection?   ;; true if the patch is at the intersection of two roads0 j' W6 Y0 K( A; f& g
  green-light-up? ;; true if the green light is above the intersection.  otherwise, false." j* A3 h- z% j% G6 b& O& c: b
                  ;; false for a non-intersection patches.( P6 y: O4 b$ B: Z' B
  my-row          ;; the row of the intersection counting from the upper left corner of the
& n  {. c. w6 r  A- s) v                  ;; world.  -1 for non-intersection patches." V  A4 c1 i, j7 U$ }5 J
  my-column       ;; the column of the intersection counting from the upper left corner of the9 p8 o: y5 t: ^- K
                  ;; world.  -1 for non-intersection patches.
% T8 [* f! V/ Q2 H2 S8 [. ?  my-phase        ;; the phase for the intersection.  -1 for non-intersection patches.
$ m; N5 H+ C/ j4 l9 l' q  auto?           ;; whether or not this intersection will switch automatically.
  i: L! H4 K  U                  ;; false for non-intersection patches.
& y( x8 b& n4 |, ]$ [$ n]
0 M0 N' c( t5 c6 x0 c
: Q& O5 w, B) S4 W& q9 {% o( p- w! R& }0 o  U
;;;;;;;;;;;;;;;;;;;;;;
3 \' o. X/ N* a4 G" t;; Setup Procedures ;;1 I5 x, M. z8 s+ a7 d; {! L
;;;;;;;;;;;;;;;;;;;;;;
) X, [0 a' }6 O- Q4 ?5 {
0 h8 Z4 n8 h, f9 B2 A7 F;; Initialize the display by giving the global and patch variables initial values.# W: H% z5 T9 U- |: c: a
;; Create num-cars of turtles if there are enough road patches for one turtle to9 h) Q, m4 }/ y9 ]( [$ P/ O
;; be created per road patch. Set up the plots.: T6 E2 W" e$ M+ L  |
to setup6 X" A3 ]2 ]* ]: a  F2 D1 }7 @
  ca9 {9 g2 p; |1 @4 d$ l6 G4 V" ]2 h
  setup-globals1 }# \# Q( B- N
7 o9 C% |* D  r( w8 y# S/ _6 v' A
  ;; First we ask the patches to draw themselves and set up a few variables: V- U8 T, p# D# n# F0 Q% T1 R
  setup-patches
1 {% G! S9 l. p+ A2 Q8 `% s: k  make-current one-of intersections+ I- o" T& `$ O' d' X4 f; R2 l3 t. B
  label-current' n& \! I" z( p4 |+ u

. a) T9 G; t& J# F+ s  set-default-shape turtles "car"% \5 D* U- S/ D) O; k9 B
/ K& B" H4 \! V: a& I
  if (num-cars > count roads)* p0 {( v" L$ `9 M7 X
  [8 N: p& _  M; k! i3 S
    user-message (word "There are too many cars for the amount of "
" Y/ H- x! U& B6 e: z                       "road.  Either increase the amount of roads "
' d$ m8 S2 z' J1 d. r' w# I8 f                       "by increasing the GRID-SIZE-X or "
0 o: [2 T" s- T, n! }% X                       "GRID-SIZE-Y sliders, or decrease the "
  J- L+ o6 z" m. R                       "number of cars by lowering the NUMBER slider.\n"# a( w$ A, B8 _' I/ A& _
                       "The setup has stopped.")
2 j2 I  P1 L0 ]$ Z. [    stop' R5 k7 E+ y( |6 |6 ~0 @
  ]
1 G$ t; [' |% }" Y% C$ ?7 Z' H, g8 g
  ;; Now create the turtles and have each created turtle call the functions setup-cars and set-car-color% Y; {" ?6 f, C( x, F2 s
  crt num-cars2 c; p# @& U( ]: m9 p
  [
* ]; e) M7 Q6 S9 s    setup-cars
* S. w! U; Z6 Y, Y* V# I$ y1 V    set-car-color
) T- x6 s0 G1 [5 S7 U4 _    record-data. N9 ?3 @5 `, I5 M& y' |0 j
  ]3 z/ a! C6 ~; Y) {$ v8 A9 s1 f
/ p. u# N* i0 n: t+ U  Y
  ;; give the turtles an initial speed  U/ o  j' q/ ?
  ask turtles [ set-car-speed ]
5 v3 ]2 ]/ a1 f4 {, q( U: ?' v4 ~/ i9 Y8 L
  reset-ticks* m% C2 |7 k: F! J1 ^  o
end
, y4 X" G# L) F7 a/ s
* O& X: v/ W; W4 b4 ^" K# ];; Initialize the global variables to appropriate values
7 V& Q9 L0 W" z/ @( Eto setup-globals
  Y0 J4 ?: F3 p2 o# \# @. _  set current-light nobody ;; just for now, since there are no lights yet7 p/ R2 b' ?& x2 ?, _; x
  set phase 0
; L6 `% r# r0 S3 y9 {  set num-cars-stopped 0
3 [; n8 U* [5 d5 M2 K* a2 S  set grid-x-inc world-width / grid-size-x
3 F7 J9 v- S$ I0 Q6 B2 o  set grid-y-inc world-height / grid-size-y
* Q5 ]0 p( ?! s7 e; x+ y" N  I* W, |8 S' [6 H
  ;; don't make acceleration 0.1 since we could get a rounding error and end up on a patch boundary7 V) M: l8 I3 _
  set acceleration 0.099
& M+ h8 B3 q5 Y8 G/ u; g  O$ kend6 S1 I3 w/ s; r0 c7 e/ h

- \" H# s* N1 _4 s. P2 k4 \8 w' s0 c2 d;; Make the patches have appropriate colors, set up the roads and intersections agentsets,3 s7 ~& H& K2 ?' V
;; and initialize the traffic lights to one setting
- z$ K1 J0 M: z2 _& U$ q0 dto setup-patches4 z8 c9 z0 v! H% T5 u: G
  ;; initialize the patch-owned variables and color the patches to a base-color
1 v) J' s; i, {% [  ask patches
' G" C6 o! G$ N$ C1 d  [1 A2 P+ g4 T: h
    set intersection? false
8 o4 G* M  Z- F& w: S. A    set auto? false+ i/ T. o0 q% U- R8 P; G" t
    set green-light-up? true
) j; y' J* ]* H& q    set my-row -1
, W' z/ m9 v/ r* W1 p    set my-column -1
6 O# I3 e( ^9 s! q; c/ i    set my-phase -18 \7 `3 A% D  O+ S+ R* s
    set pcolor brown + 3! B7 @2 R  S; ~  E! Y
  ]
% c7 W4 e7 t, r
6 Z: U& _. o4 D+ s8 I) P  ;; initialize the global variables that hold patch agentsets9 w7 B8 ]% e/ Y5 G, a; Y
  set roads patches with+ L+ R0 R( Y' V. N8 O% z
    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) or5 Q  j1 u+ X! i1 f( A0 h
    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]
: ~" ?6 V5 t$ s7 T& u  set intersections roads with3 X7 |2 U  l9 a! ?4 T
    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) and/ @5 P2 c- i* A6 @' P1 ?
    (floor((pycor + max-pycor) mod grid-y-inc) = 0)], V  z" H$ v, c+ Q7 _
3 K* p% d3 C( ^) [, I: g
  ask roads [ set pcolor white ]7 h" O, S& T5 v: W7 ?
    setup-intersections& H8 O- L: y* y) J( w; R
end' w) z9 C" k" {2 |! |2 B
其中定义道路的句子,如下所示,是什么意思啊?
6 W, b3 ]. J9 D+ X! i! h& f8 P set roads patches with
+ [6 |/ L/ d& e8 u: [7 U4 x    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) or- X3 p/ i$ s) J! H7 t* E- V9 _
    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]
* I1 m, L! f- c9 C: z7 B% T5 R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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