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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。5 u. v* T1 g8 i1 W2 W9 O2 p
netlogo自带的social science--traffic grid这一例子当中,9 |6 n0 `1 j* v7 z2 r0 s6 k. l
globals& M5 D; s0 D* g( j! E
[
! n# q# p! {5 u9 L1 a8 E  grid-x-inc               ;; the amount of patches in between two roads in the x direction# b( G3 ?; |' [9 _
  grid-y-inc               ;; the amount of patches in between two roads in the y direction2 e$ p4 X9 ?4 `& b% Z5 J5 p/ i" J
  acceleration             ;; the constant that controls how much a car speeds up or slows down by if* t& v6 O9 z& s- v( Z% J
                           ;; it is to accelerate or decelerate9 m7 Q7 A- s3 V: m6 ?9 _
  phase                    ;; keeps track of the phase
! Q% }4 W7 N, v9 D  num-cars-stopped         ;; the number of cars that are stopped during a single pass thru the go procedure, I& a( `* ?8 {; s! B" ?/ E1 M5 S
  current-light            ;; the currently selected light) N7 z! k5 B5 ]7 m6 m7 e5 [* u7 c

7 m" Z: l- f- s; @1 a4 H; y  ;; patch agentsets  V6 U1 y: L0 v" ?# |
  intersections ;; agentset containing the patches that are intersections
1 L9 a+ b6 f3 P) [- |, G7 _8 a  roads         ;; agentset containing the patches that are roads
7 h0 s" `9 z8 d$ f, ~: i]. ]% A8 ]% |2 J& d4 j

& m1 J9 m) }) P6 Zturtles-own1 ~4 O) e3 O$ m2 A5 |9 m' A! T7 t
[3 \! {) G( _. A- Z, p
  speed     ;; the speed of the turtle
- Z0 B4 e, `5 O6 t  up-car?   ;; true if the turtle moves downwards and false if it moves to the right
5 a8 `, q% K6 W& o+ }( k  wait-time ;; the amount of time since the last time a turtle has moved
6 V7 b) d+ U6 k: b+ C4 C]
+ N3 r3 ?# Z) w/ z# @/ j0 z4 M- X. q5 B9 X* ^" h
patches-own
  C6 Z. I4 d+ A# h% Q# f[
; o. L2 C. Q! y; e! G8 b  intersection?   ;; true if the patch is at the intersection of two roads
% I" {, j+ P; G" c# s8 N0 {8 [* D  green-light-up? ;; true if the green light is above the intersection.  otherwise, false.
5 E! [  t/ i( ?' G0 @                  ;; false for a non-intersection patches.
( L9 y- G# H  H  my-row          ;; the row of the intersection counting from the upper left corner of the
$ |, z) v* D2 E( e) }                  ;; world.  -1 for non-intersection patches.+ s/ y" E  o9 Z7 x( }3 X
  my-column       ;; the column of the intersection counting from the upper left corner of the+ O' a- @) e- C
                  ;; world.  -1 for non-intersection patches.
; ?' X, t- P7 M* |# k  my-phase        ;; the phase for the intersection.  -1 for non-intersection patches.  }2 f5 _4 ^5 M: K; _' M3 d+ }
  auto?           ;; whether or not this intersection will switch automatically.
; m$ e: L& ~. S: P  D/ {) ~                  ;; false for non-intersection patches.% X4 s' M! _# D& ?
]; s4 f  K6 s% H4 F# |& y
- D0 h- ?: ]5 M2 X' f/ v6 }

4 ~8 ^3 O, t/ J( H: S5 X, u. d;;;;;;;;;;;;;;;;;;;;;;% M2 k  g, F) z  q( |6 Q
;; Setup Procedures ;;
7 C: B+ i1 E+ Z: x  v;;;;;;;;;;;;;;;;;;;;;;
6 O  j' o! Y- O" d+ M5 d2 a) A/ w& l6 H- q0 B6 [4 t+ m) M
;; Initialize the display by giving the global and patch variables initial values.; V3 }6 j% z4 n
;; Create num-cars of turtles if there are enough road patches for one turtle to7 s: k, M0 k; Q& S" u9 Q
;; be created per road patch. Set up the plots.
' R# E: r% L8 M8 @/ @' Nto setup
( G9 }+ Y3 R! p% s! [  ca/ ?7 Q1 \! G$ {
  setup-globals) F: y4 G, G  P4 T  f' D

& G, |1 c7 `7 u) x( [  ;; First we ask the patches to draw themselves and set up a few variables
4 \0 E! j- n- t8 e+ Q# r  setup-patches; c/ L. L; I' {0 A- I
  make-current one-of intersections
  s- U' S+ w' l  `* j5 S2 H  label-current( h! ^: u# T, b1 s- x; l3 q

# y$ c* c( m$ f. z; e. t7 }  set-default-shape turtles "car"9 R$ r1 Q& s) @
; [9 j& l& h$ a- v6 P% T; X
  if (num-cars > count roads)5 a! t! U& a+ J
  [
! p: W1 ~' C* j  p; u    user-message (word "There are too many cars for the amount of "9 x. b( p) V2 o+ [% u
                       "road.  Either increase the amount of roads "2 U" J# s2 t6 t% d
                       "by increasing the GRID-SIZE-X or "2 E3 y, a6 A8 N* I
                       "GRID-SIZE-Y sliders, or decrease the "
3 U2 S- G: g$ a. @  k# G                       "number of cars by lowering the NUMBER slider.\n"
- K$ j. O0 z: S! w. L                       "The setup has stopped.")
; @0 r! |8 a: y  ?* a( S. ~, s    stop
4 D- U& i3 w1 ^, n  ]* N. m8 m  n% U" K
, [$ j  a0 {% |, w% K/ f
  ;; Now create the turtles and have each created turtle call the functions setup-cars and set-car-color% b8 k( I2 v7 e: r6 d- @2 Q
  crt num-cars
2 b4 q; v1 y2 ]6 c4 X7 x* t  [
/ b8 x: s8 e/ G; N3 j* X- S6 A4 \    setup-cars
' c2 u% O. }% F! V2 [    set-car-color
5 T0 K: b5 n0 `9 P' m- W0 g7 n' L7 s    record-data
6 }# k1 B  ?/ |. d' M! V  ]
# I5 b+ T' ^1 B/ c8 p% b! |
4 @/ y. ^: i9 P4 ?  ;; give the turtles an initial speed7 Q( O. N& P& j  c% ]6 p
  ask turtles [ set-car-speed ]
  P  _$ {3 C1 V5 v' X( q6 I. q% g" ]
  reset-ticks* w2 ?5 C) R6 v9 W! j
end
3 R) A0 m, `" L% t+ C5 @
- y1 S& r- l6 w, H8 J;; Initialize the global variables to appropriate values# H  C2 k) Z2 }5 J7 d1 f
to setup-globals
( |- b7 n1 \8 g. P1 B  set current-light nobody ;; just for now, since there are no lights yet
3 a3 U1 G, C7 \: B# Q  set phase 0
5 d  p7 g7 K9 b& r- i2 {  set num-cars-stopped 0
3 ~% C3 ?" b" O( @) S& ^9 d: w  s8 ?  set grid-x-inc world-width / grid-size-x
) n- j( V5 D0 j1 k5 D  set grid-y-inc world-height / grid-size-y$ i; L0 r% H4 Y' d* G; n0 p; d
* T1 D" m$ J6 {1 [& f7 V
  ;; don't make acceleration 0.1 since we could get a rounding error and end up on a patch boundary
3 T: T* M% t( S9 Q8 g1 d+ i  set acceleration 0.099
! Q& Y. M5 }3 ?& T+ Hend* o! F! Z. ?) N9 F2 d9 D
# q$ D9 `3 z  t& V: g0 |
;; Make the patches have appropriate colors, set up the roads and intersections agentsets,$ w2 N- @. v! Q; ^2 w' Z# D8 d
;; and initialize the traffic lights to one setting8 u) E0 T( j5 F
to setup-patches. Z5 Z8 U' |, d- O
  ;; initialize the patch-owned variables and color the patches to a base-color( i8 m/ b2 l! @% {7 D
  ask patches5 H6 I/ n! }: ^
  [1 g% }4 M! _) z
    set intersection? false
" b! r$ L$ U  L& r" r9 e    set auto? false
% P6 a$ a9 o% f    set green-light-up? true
* `2 L) C+ \7 X+ l5 X    set my-row -1
( v/ t( y) y, R* ^9 Q& O    set my-column -1( Z) K2 P. M0 J/ {  r& w. w0 M" N
    set my-phase -1" z8 E1 z4 i; ?- F/ v
    set pcolor brown + 3
2 }% T& ?$ }+ O5 m! @6 a  ]
- @% W, g1 p5 t2 e4 C+ `" y+ u* D* J1 j$ @5 t4 d6 c# P) \8 T" [
  ;; initialize the global variables that hold patch agentsets6 F  k$ Y; a% p9 h! |8 @) K
  set roads patches with8 y0 A3 j: d1 W4 P8 i% r9 [
    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) or
4 F0 P9 h+ `' T1 j' i    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]; v9 l* T$ I6 B. B9 W* C0 k5 u
  set intersections roads with
& M2 T7 y. h9 G+ k, B$ j    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) and% m4 n/ ]  y; ]1 f
    (floor((pycor + max-pycor) mod grid-y-inc) = 0)], _) N. ]+ V/ k/ t- t+ ~1 k2 d) ~& u+ z

' A3 ]  o+ h, }7 R* p2 b* y& F# t  ask roads [ set pcolor white ]) w, O+ W" ]! K2 [/ C
    setup-intersections! `6 n2 \! X8 J; ^9 s  ^
end/ J  l, d3 v& C. {5 p
其中定义道路的句子,如下所示,是什么意思啊?
3 e7 q& z7 v; J. l! n; U: T$ E0 b set roads patches with
4 U. O0 H) k  x* v3 \8 R5 u    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) or
+ M5 X1 W6 Y6 Q6 A: B- i    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]
8 [0 }" W; w- f3 ^  _2 e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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