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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。
( E& m! j" P4 ]( ]netlogo自带的social science--traffic grid这一例子当中,1 ~! s7 H- g( y% T5 {
globals5 o% N9 H) X( [- j: {4 ]& i3 K7 b. v
[
# _! P" C# j- v' D  grid-x-inc               ;; the amount of patches in between two roads in the x direction
* f2 |5 _' C1 ^. U2 Y- g' ~# r  grid-y-inc               ;; the amount of patches in between two roads in the y direction
) ]3 w8 S9 i: f. o+ e. v2 V  acceleration             ;; the constant that controls how much a car speeds up or slows down by if+ L! X; U* h# j( G; L" P
                           ;; it is to accelerate or decelerate
4 H% p* p, h' K8 B* }9 H  phase                    ;; keeps track of the phase
. V3 f8 u- z/ Y  num-cars-stopped         ;; the number of cars that are stopped during a single pass thru the go procedure
7 M+ E* w/ m. h" t+ ~  current-light            ;; the currently selected light
) _1 `; m/ W3 \7 ^
2 X+ x' G; d2 L! h1 R* u  ;; patch agentsets
) [1 y  E' Z7 O# b$ C/ [0 R  intersections ;; agentset containing the patches that are intersections8 t+ G4 m3 ]/ e, z( L6 O
  roads         ;; agentset containing the patches that are roads
/ [( L  a- W5 G4 M* T]* ?3 f& `' K) s( P* X9 w
( Z, x. A* y% K& L
turtles-own0 D2 {' o  X/ b. `0 r+ Z
[
# `; {! u( p  p$ R6 m  speed     ;; the speed of the turtle$ B# T5 `8 B% D8 R1 f/ n
  up-car?   ;; true if the turtle moves downwards and false if it moves to the right
; G& L2 N0 w# C( \" h! n5 |# h+ d  wait-time ;; the amount of time since the last time a turtle has moved
2 U8 S( {) B& y' Y4 J  G! L]- M0 L8 Z- N7 ]1 i

4 N3 G, l$ w& Upatches-own
9 d8 T& b1 q# q! x' E1 m6 z* p[/ S2 y1 X# r- z
  intersection?   ;; true if the patch is at the intersection of two roads
. a6 o% }- ^! X  k  green-light-up? ;; true if the green light is above the intersection.  otherwise, false.
2 i3 Q% T3 Z9 U                  ;; false for a non-intersection patches.: }- m3 w1 O6 b
  my-row          ;; the row of the intersection counting from the upper left corner of the
" D) V8 U& {9 }- }                  ;; world.  -1 for non-intersection patches.7 M* q4 F% L' y+ b  o- G9 `
  my-column       ;; the column of the intersection counting from the upper left corner of the# m# k) }* U2 R3 z
                  ;; world.  -1 for non-intersection patches.1 D4 Q9 R. m- Y- r$ x
  my-phase        ;; the phase for the intersection.  -1 for non-intersection patches.2 R, `) [1 U+ e* ?% Z! u0 [1 V3 h
  auto?           ;; whether or not this intersection will switch automatically.0 I: _7 M% J4 `/ p# Q9 N
                  ;; false for non-intersection patches.
. L# Q' A5 f, b: G7 V; Z]
! C. h5 M6 F! ~  Z$ f, b  r9 c3 Z- G1 z3 u' O4 W1 x) j1 k/ T

8 x- R. o! P" z& j! W;;;;;;;;;;;;;;;;;;;;;;, ^2 H) C/ e0 x/ T, k
;; Setup Procedures ;;: A9 `5 _0 k6 Y( J  J9 I
;;;;;;;;;;;;;;;;;;;;;;" B) H; ?9 T; K7 g

: w/ v2 K. K! R! M4 [;; Initialize the display by giving the global and patch variables initial values., g  t7 R7 k: _. _2 b, d; V, l
;; Create num-cars of turtles if there are enough road patches for one turtle to9 j* g2 i: ?/ j4 n) P, E/ r8 r
;; be created per road patch. Set up the plots./ i) }9 ]5 V" r7 |% p- A& Y3 u
to setup4 Y4 m4 }0 h7 E4 f( I' I, D
  ca! e2 ~& o1 [7 |; u8 e+ w
  setup-globals5 l8 Y$ H% L/ T6 H% x. F
6 X0 A& M5 A) R1 P# G
  ;; First we ask the patches to draw themselves and set up a few variables
& `- [7 G7 {4 S- O& Q9 q2 @6 X  setup-patches
: j% C9 n% [& d8 t  make-current one-of intersections
( B4 a. D, i, d1 x7 h0 ^  label-current8 T+ ^0 X. J6 p' p
* b# [5 U3 C9 I
  set-default-shape turtles "car"7 G4 D$ v$ E1 m  z$ I" E6 W' J

* f% i' ^/ f7 k' y' h. \( ]6 W  if (num-cars > count roads)- C% r/ L8 \+ c% |
  [- Q$ \% _. }' c; s( \) `* u
    user-message (word "There are too many cars for the amount of "$ a- J& T* K, r/ H
                       "road.  Either increase the amount of roads "6 K+ m# H7 Q6 k, E" K1 F3 {: T
                       "by increasing the GRID-SIZE-X or "
6 H1 R' L! k- E! i# e9 B                       "GRID-SIZE-Y sliders, or decrease the "
) z* w- i5 @. h3 L9 H                       "number of cars by lowering the NUMBER slider.\n"
1 r$ v. S1 A+ R                       "The setup has stopped.")* b9 L9 f- ?3 r  [! G/ {
    stop' e) O# N# h7 V& s7 z
  ]+ e0 d- T5 ]) ^5 [

- F, B; I9 q! `) D$ d7 H  ;; Now create the turtles and have each created turtle call the functions setup-cars and set-car-color3 j$ I5 e* ^$ i1 Q' b- r& U7 q
  crt num-cars
9 V( R" Z& C. h3 R" _  S/ a/ n  [
2 \" Q: h9 C( O  x; d2 ~! T, ]    setup-cars
7 e0 g* D1 J9 d' Y( U( H  E( ]    set-car-color
% b# ~1 u0 |" p, I5 b5 e% B    record-data/ ~/ C- n; ^( n* Q( u9 c/ A. c6 K
  ]# r0 G: b* _+ W5 m
( A: ^$ F% E7 t( B$ G4 b; J6 l
  ;; give the turtles an initial speed
' M/ x+ T( r8 X0 H$ X* S6 q  ask turtles [ set-car-speed ]
8 r, s: ~0 z8 [% l. d
8 ]0 R" A: H. B/ ]! o8 y  reset-ticks) G- e" G9 S3 P" V7 h3 e1 n
end, o1 ~$ i% [+ G+ D, b) Z
7 |: v$ a/ Q8 X$ q: J% c
;; Initialize the global variables to appropriate values+ m2 i  b& A! H3 u" x* M& ]# d! J
to setup-globals" x+ w8 D+ I+ a0 d% R
  set current-light nobody ;; just for now, since there are no lights yet" O# K% A6 v& w
  set phase 0
' \) X: j# E. [  set num-cars-stopped 0
6 F# W) @+ K& u; d! O  set grid-x-inc world-width / grid-size-x8 F/ U8 z/ P7 A
  set grid-y-inc world-height / grid-size-y" S; |; f9 v8 r7 G
6 ^4 A3 O) U) p  J
  ;; don't make acceleration 0.1 since we could get a rounding error and end up on a patch boundary
$ I% X8 _9 E/ u% T  [0 [( q! E  set acceleration 0.099- P1 \' z: I  r8 ^2 m0 ]$ b
end+ ~% T, `( T8 H- A0 ]
9 k) \- L" V6 p4 Q% t& b  y( g
;; Make the patches have appropriate colors, set up the roads and intersections agentsets,5 i# N9 D, t9 Z7 `+ t7 u# ?9 k
;; and initialize the traffic lights to one setting
) o4 y' W: G  }9 B9 u6 ^to setup-patches
' [3 Q0 b0 L' `; p$ f1 r  n& A  ;; initialize the patch-owned variables and color the patches to a base-color
6 O$ [* N, L% }- z$ F' j2 q  ask patches  s6 M3 X0 G5 D) P5 o' y" o
  [  ]" Q; ]# f8 o( ~! p6 _
    set intersection? false; r# ]% a/ @$ z9 I) s8 Q$ i
    set auto? false
8 l. d+ o& }5 X' N$ X1 K4 u    set green-light-up? true
' b' }5 F5 Z7 s1 Y5 i    set my-row -1
% u9 T& k2 ]/ N2 h' K2 y* d9 P* l    set my-column -1
, ?! m( B: ^$ a    set my-phase -1( C! u. Q" T/ }" i( Z' i
    set pcolor brown + 3
. g0 M8 g8 ^% g0 t2 D! w6 p  ]
0 z' C$ _% C# `- N2 n  B
5 s: N) L, @6 S  ;; initialize the global variables that hold patch agentsets6 C0 \# m  v( V
  set roads patches with: q3 d6 g+ }4 H
    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) or
2 y% a0 h# h3 U    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]
. }* i% v* c: R( g8 N1 o: C  set intersections roads with! q9 `1 E7 j4 K/ W$ L/ y& I
    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) and0 b" F' w. s( \9 g3 b+ y7 i
    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]
" n7 O1 j9 s3 B& A0 K$ }7 X* ?* Q/ x" y
  ask roads [ set pcolor white ]0 L& Z! O3 ~, e% [8 z! G
    setup-intersections
5 O' s" j8 c$ kend5 ^7 x" j0 p- c9 d1 {
其中定义道路的句子,如下所示,是什么意思啊?+ h1 I2 I- g3 E% y* H6 u
set roads patches with+ r4 e# g! k) {/ U
    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) or
5 I2 w. t& k# c& ^2 P    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]
; j! C- N& L1 f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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