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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。
2 A- ?) y' L6 @6 o" R3 j/ Unetlogo自带的social science--traffic grid这一例子当中,/ P, }# g' z# G& W3 C; c- e. W- [
globals4 P/ p( A* R% K+ P
[
/ y$ x# M5 g9 V* l: y" P  grid-x-inc               ;; the amount of patches in between two roads in the x direction" ?; a- g# o) @8 r2 ~5 b
  grid-y-inc               ;; the amount of patches in between two roads in the y direction
5 e# H2 [: f  A( Y! C! t' Y7 w8 e" O  acceleration             ;; the constant that controls how much a car speeds up or slows down by if* L: {3 x3 [% e" D$ T7 c( @$ R# ~
                           ;; it is to accelerate or decelerate+ f! r- s! V) f9 D& o8 M
  phase                    ;; keeps track of the phase7 i9 ?( t2 K: i+ k2 |8 v. s
  num-cars-stopped         ;; the number of cars that are stopped during a single pass thru the go procedure4 B' @9 `' C- w7 ]9 _& l7 m; `
  current-light            ;; the currently selected light. J, Z- H: D9 u6 n! h* g! Y" i

( T. F1 V6 G$ J' Q) P6 J0 d  ;; patch agentsets
8 _) e/ y. ]0 Y  {: \1 e  intersections ;; agentset containing the patches that are intersections
8 {( [+ N# v8 ]6 }) c  roads         ;; agentset containing the patches that are roads
; y4 I7 a7 ~/ V  k]: [3 u& W* k% {7 e

' T; q; @4 D) `9 Vturtles-own
7 X3 a% m( S  c1 t8 R$ k& U[: n6 L/ Y  G8 ]3 w1 D- @  a
  speed     ;; the speed of the turtle, N4 A: U' o8 t0 P) ?
  up-car?   ;; true if the turtle moves downwards and false if it moves to the right/ u! x( Q# c6 f; s2 O) f! D
  wait-time ;; the amount of time since the last time a turtle has moved
% B0 W8 u1 m: q' o+ p]& M. K* y0 Y2 ?5 \# j; t7 B
2 {! ~5 y" b* X( `3 T$ Q5 E/ C+ W
patches-own. L9 J, R( y! A% @# {  ^/ j! ?; {
[4 I5 l/ G5 Z2 L! b# ~  [0 z; c( R4 t
  intersection?   ;; true if the patch is at the intersection of two roads% T! L  y& W2 P% F" ~# ?7 }
  green-light-up? ;; true if the green light is above the intersection.  otherwise, false.
) H4 K( B3 \7 n                  ;; false for a non-intersection patches.
" \, x$ M) Z0 u6 M  L) ]  my-row          ;; the row of the intersection counting from the upper left corner of the' A8 A/ N3 m* h$ U, |$ R: {+ K
                  ;; world.  -1 for non-intersection patches.
; n3 T$ C" ?) m4 T- z8 h/ ~  my-column       ;; the column of the intersection counting from the upper left corner of the- t6 ^( T9 o4 u- O* e, K" M
                  ;; world.  -1 for non-intersection patches.6 e& j1 N1 N3 \! }4 R
  my-phase        ;; the phase for the intersection.  -1 for non-intersection patches.
6 h& v5 n. s+ u$ O7 o. i  auto?           ;; whether or not this intersection will switch automatically." W9 j/ U. ^$ q/ d& j& T1 r! b
                  ;; false for non-intersection patches.
0 K, U* [" }( Y8 s]3 }4 c+ x! D0 J+ F% ^% r
) O" C! [# W9 G+ h
- i- U: K* [: d; N3 y% e# P
;;;;;;;;;;;;;;;;;;;;;;
! x: `$ O8 Z7 I0 l  x$ D7 z+ s;; Setup Procedures ;;
: h; J8 a8 e" B8 u" e;;;;;;;;;;;;;;;;;;;;;;/ R/ |6 F# y+ f4 Q) M
; M" G% `7 c) {0 U+ q% V+ Z
;; Initialize the display by giving the global and patch variables initial values./ v; Z6 X( o; G5 Y. E
;; Create num-cars of turtles if there are enough road patches for one turtle to$ G5 X7 b1 X3 N+ n% O0 ?9 u. l
;; be created per road patch. Set up the plots.
$ x9 ?: B. y+ t+ Sto setup
! ]$ f+ P* T3 @& v0 G  ca
8 A0 ~0 j8 \9 F% j8 T" p  setup-globals& R, N3 [8 L  _  ~: h+ }8 V7 `

# F( C6 c4 q! k# V3 |; B9 l  ;; First we ask the patches to draw themselves and set up a few variables
2 q  S, L  Y3 |, G2 Q  setup-patches
1 T2 G; R" D3 D  make-current one-of intersections  u5 K( Y( [9 }* t
  label-current
3 K1 o' S7 Y: y! d/ ~- L' Y9 ?$ D  C) E: E3 h
  set-default-shape turtles "car"
* e. l& P5 \( t! `8 `5 D% s
7 {. G6 o' s, U  if (num-cars > count roads)( q1 }/ G7 K4 `0 w
  [
+ E6 l1 J8 b; `# h7 \( t" _    user-message (word "There are too many cars for the amount of "
- b0 d, C' D1 |                       "road.  Either increase the amount of roads "! Z; {, I' P/ N6 m) f
                       "by increasing the GRID-SIZE-X or ". |  v1 @! {+ B4 B2 q) E# O
                       "GRID-SIZE-Y sliders, or decrease the "& h5 c5 ^8 Q& d; n
                       "number of cars by lowering the NUMBER slider.\n"
* _, P7 K* Z7 U                       "The setup has stopped.")3 v% G# L0 \) ~7 H
    stop
; ~" a$ ~- B( N1 G- z" j  ]6 d8 z. R, k2 N* m9 w, E
! n* B3 e+ y" X; {
  ;; Now create the turtles and have each created turtle call the functions setup-cars and set-car-color! r4 D) u. K) [+ w* @9 z
  crt num-cars
% y6 Q( H5 N' d7 E  [- s2 J2 S. t0 N5 o: r
    setup-cars) B# Q4 E# O8 s6 E$ y) {1 a: s
    set-car-color$ Q) s5 L8 |* o) U0 Y$ g2 P  A
    record-data4 b# a0 ]( ?; a" m% n' \
  ]
4 G# {0 k2 O# Y* h* C- R7 A
5 d" ?) X$ P; X" y3 C* W  ;; give the turtles an initial speed
' u& U7 _- e& G6 ?' C  ask turtles [ set-car-speed ]. F: H6 w" z% \8 I& J  j* E! O
( k! o+ r* M0 o5 F
  reset-ticks
8 A& E7 r( M9 w9 B- X9 }end
- ~2 `7 \7 P; }! c( B: G6 _) r, `* j0 G3 H) w
;; Initialize the global variables to appropriate values' x( G0 I( f4 P" h3 f
to setup-globals* N0 F# S0 _$ Q" c. [8 V, z  G4 E
  set current-light nobody ;; just for now, since there are no lights yet" L. G2 A" m: o! Y
  set phase 0
( e  A) X" Q4 R' Q  set num-cars-stopped 0. b; R; K2 Q" w2 T3 ?
  set grid-x-inc world-width / grid-size-x
6 }; O5 E: F/ g; z9 O3 z% |  set grid-y-inc world-height / grid-size-y
* Z) v; U0 R. w( x3 `
4 F, C" S/ h8 D+ N$ d4 |5 o; q  ;; don't make acceleration 0.1 since we could get a rounding error and end up on a patch boundary
) b; K" E* q6 a% N, j! N  set acceleration 0.099# {; k5 @  N$ [! h) Z
end: H3 z* e* s" r6 o

/ @' F, l" s$ \% F+ z6 E3 _1 h;; Make the patches have appropriate colors, set up the roads and intersections agentsets,
2 S7 E" s$ _* h# O# N;; and initialize the traffic lights to one setting
$ A# v4 }* d$ vto setup-patches6 V7 Y9 Y7 T* n3 ?+ D+ n
  ;; initialize the patch-owned variables and color the patches to a base-color
  _) I: N6 V& {! Q- Q  ask patches. J' H+ ~3 r7 H4 i% e6 [
  [4 k( n8 {; s) E8 r& n
    set intersection? false7 D" `, K; V# C, L4 ^+ d6 r
    set auto? false' H* k6 e2 @# }5 a( `1 ?1 g
    set green-light-up? true% \- D# s# }( q
    set my-row -1
0 [5 U% H) C, \8 Z# _+ _    set my-column -1- d* a" L9 z  c/ d* t# i, M
    set my-phase -1
3 t, j1 {# o! c    set pcolor brown + 3  t" N2 I  j. Y! T5 V0 Y
  ]
3 n( ?( b; m5 X. a) _4 e# c0 r  \0 h# Y) [& l8 @
  ;; initialize the global variables that hold patch agentsets# A1 g$ L1 |$ {/ m& [
  set roads patches with
8 c7 ~5 f( c9 T& R! B$ [3 X3 g    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) or! `# q3 i$ E7 |! i3 Z" H- ]$ A
    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]7 X% ~* M/ C  Y% ^
  set intersections roads with
$ F, l  z8 e+ p4 g# K1 W! A    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) and* Y* Q! \( x& y0 R( g0 C6 N
    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]9 o* `; n; `4 Y0 O/ v
- M3 _( h; R0 q% Z/ y
  ask roads [ set pcolor white ]
4 z. ?+ U, V; c* L9 \* X7 G! R    setup-intersections& G& _0 P$ L, H
end. V) O, I* g% d$ W
其中定义道路的句子,如下所示,是什么意思啊?
7 E/ o; _" a" I set roads patches with- g1 B/ a$ ?; s" K4 x# L" E" b
    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) or# p5 @% C) s) r; b3 a
    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]2 x! M4 Q9 f8 Q# 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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