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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。( F* [, k' ]  t4 H
netlogo自带的social science--traffic grid这一例子当中,5 Q$ @$ ^1 x, F. c+ e4 D
globals
  Q' g' ?" C3 k, H- ^[
  t! Y: G8 Z  T0 N; a  grid-x-inc               ;; the amount of patches in between two roads in the x direction. a- D! k4 {, [/ J0 x
  grid-y-inc               ;; the amount of patches in between two roads in the y direction
% n& Y! l" @' G  acceleration             ;; the constant that controls how much a car speeds up or slows down by if7 r% m6 e7 _+ c& r+ H% U
                           ;; it is to accelerate or decelerate) ?" [% W2 K* L
  phase                    ;; keeps track of the phase
9 x' ~( q& ~! c2 E  J  num-cars-stopped         ;; the number of cars that are stopped during a single pass thru the go procedure* c6 B$ X/ _6 b& h
  current-light            ;; the currently selected light
: i7 _2 z- u1 z1 A9 D% X$ i
( H1 q) v2 e' a6 D$ f" r  ;; patch agentsets
( K, l5 I; {' C  intersections ;; agentset containing the patches that are intersections
/ \" S% ~' \8 @- |1 m8 x$ o  roads         ;; agentset containing the patches that are roads0 x+ a; S6 a2 j
]
3 C% M: n& W9 n- m" @) z9 G  d/ b& r3 E  |8 n
turtles-own. k1 L8 |+ E" a. L% A
[) z% N5 M; X- m% w( ?9 ?
  speed     ;; the speed of the turtle" l9 S# f; l$ p- N
  up-car?   ;; true if the turtle moves downwards and false if it moves to the right5 f# N/ f) n7 a/ \" b
  wait-time ;; the amount of time since the last time a turtle has moved
1 Q) K! y/ }5 c]& ^& d* B* w/ s8 F& l+ P

% I0 G' c4 D. H$ Gpatches-own
, V6 d- }% A; r) C$ B' E+ W[
+ a9 \6 w6 V. d9 \! M- x  intersection?   ;; true if the patch is at the intersection of two roads, r# c1 S2 I+ F8 U$ z7 `
  green-light-up? ;; true if the green light is above the intersection.  otherwise, false.
* [1 u2 c) l# i. ?5 K3 r8 m4 I9 K7 W                  ;; false for a non-intersection patches.
. d% r# N* H7 ^  my-row          ;; the row of the intersection counting from the upper left corner of the
/ N) O+ B9 F9 l5 I, j) w( S                  ;; world.  -1 for non-intersection patches.. _$ y( Z; i3 l+ j6 T
  my-column       ;; the column of the intersection counting from the upper left corner of the, M! D* n" b* v* ?; N9 h! i
                  ;; world.  -1 for non-intersection patches.
* Q5 Q1 s1 o. {  my-phase        ;; the phase for the intersection.  -1 for non-intersection patches.) e4 t1 n& _2 U8 [% a
  auto?           ;; whether or not this intersection will switch automatically.
! j) _0 {, u3 k( R' R3 _( i                  ;; false for non-intersection patches.
! V8 o" ?: @; s& G  B7 e" n]6 n9 {8 `1 \: s) X
$ ~6 o) t' l/ f+ E9 k
' V1 G8 H( j+ q6 y/ @* S: ~$ i$ h9 a
;;;;;;;;;;;;;;;;;;;;;;( u( x& H, D* A1 W9 L- N# s+ i
;; Setup Procedures ;;) M4 O" V+ Q2 i9 w
;;;;;;;;;;;;;;;;;;;;;;! P7 R# l+ D$ O  L  K6 ~* Y3 q
- M  p. G/ A7 O& _+ J, u6 I2 N
;; Initialize the display by giving the global and patch variables initial values.
" ^- |! N  l; K$ m  H& d;; Create num-cars of turtles if there are enough road patches for one turtle to
  A! ~7 Y( L6 Z& |8 W;; be created per road patch. Set up the plots.
: |5 s7 ~# X) w$ Z0 \( m8 S" g) g$ v4 `to setup+ _& Z! |3 r3 p0 p$ r
  ca; z0 c) T4 V. d. S( J+ V
  setup-globals
1 `& b2 y$ R% q1 I2 D
8 s  Y9 b; V5 z- |: f) `  ;; First we ask the patches to draw themselves and set up a few variables
3 ^  q8 X* L& g# p; {  setup-patches
9 R1 X/ i2 a. G) |1 v% ^8 P  make-current one-of intersections
5 j% q4 Y  y( x. [4 T  label-current1 o  Y0 ]% s) l  O; R

  K9 @+ u, ]/ y6 {, d0 t8 A  set-default-shape turtles "car"
5 I, ?9 r% @2 _9 X' y: }+ b8 l5 t! i/ G  o; ^# f# J
  if (num-cars > count roads)
0 |. l6 d  W3 ^" K# D5 W  [
( f6 A/ ]$ _% s9 a; e0 l( @    user-message (word "There are too many cars for the amount of "' \, X% N0 R+ P3 ?
                       "road.  Either increase the amount of roads "( i0 ?2 \7 I7 \. j! h$ d
                       "by increasing the GRID-SIZE-X or "
1 \: |/ P! Z; T                       "GRID-SIZE-Y sliders, or decrease the "- p+ w- ~9 j' f1 L& z
                       "number of cars by lowering the NUMBER slider.\n"  }7 H) }1 D+ F" W8 ?
                       "The setup has stopped.")- X, t  c3 u$ `' S  g
    stop" Y6 @7 @% o. U
  ]5 [, k; ^- ]5 |) b% e
8 Q7 s6 I. ~8 S) z' W
  ;; Now create the turtles and have each created turtle call the functions setup-cars and set-car-color
6 @5 S7 z3 j: f3 M  crt num-cars% P% g1 B5 d6 e( s. f" X: G- _/ T- Y
  [
# y" p! {( G" u/ q& U9 R8 s" S5 T    setup-cars
8 c( x5 L' Z: A, P  t9 \    set-car-color
+ n7 o# T' \% J+ u5 @- D# F    record-data9 P8 t2 m. w; `( A; J
  ]; w# m5 F4 [3 Q! a1 V

/ s" j8 ~6 k& J, N" g) s: y" @/ r3 Q  ;; give the turtles an initial speed" u9 y1 o3 }( T( g5 Y
  ask turtles [ set-car-speed ]
' O6 w2 Q/ h' H% L/ Z- a: x4 ~& V
! Q# w4 f- X+ z; p  reset-ticks
5 i! ^+ c# M% }4 o, y) ^4 _end  Y$ ~# L( ]3 A% {
  v$ b6 G! T, P/ U7 q
;; Initialize the global variables to appropriate values
  r5 I2 z8 w4 [$ Uto setup-globals
5 W1 C9 h+ p& l# B  set current-light nobody ;; just for now, since there are no lights yet
, `) e* r8 e, B, l3 d' @7 Y  set phase 0
* q/ t, [" X$ s* Z) f, K  set num-cars-stopped 0
( [# F; _1 A- F% q3 B# i- z  set grid-x-inc world-width / grid-size-x" W% R* r; q0 U' M) f/ \6 C# M
  set grid-y-inc world-height / grid-size-y  Z$ ?. ^) }* [; w

/ \# }, d: v* v5 g5 ^( [  ;; don't make acceleration 0.1 since we could get a rounding error and end up on a patch boundary
# G8 R8 g0 v( r9 c2 o2 P; K  set acceleration 0.099& ^: d. x0 O. y$ D) H9 N: h
end
( s1 i3 ^: \1 s4 p9 B
+ |/ Y0 _3 Z0 {# c;; Make the patches have appropriate colors, set up the roads and intersections agentsets,
4 K0 T% O8 B5 Q- k' e6 ~3 [' d;; and initialize the traffic lights to one setting
$ a' y" U6 R" q/ J# o% mto setup-patches
  j# ]. \" J) y( g) N4 t  ;; initialize the patch-owned variables and color the patches to a base-color
  `4 l; D1 W3 O+ `  ask patches
5 v, Q, C. E. I% I+ l' I: C  [! N& _" K  m- r  ?9 C2 k
    set intersection? false
% `4 m  T/ s! z3 @8 {: B    set auto? false
, w% v/ s* ^/ y9 _    set green-light-up? true9 J  F4 D7 S0 T& O  E  S
    set my-row -12 Q9 g. E  b% A' j
    set my-column -1; n. _8 ]- s  v0 G* }; J! Y
    set my-phase -12 t8 u* x' f3 A) M' p0 n( r
    set pcolor brown + 32 v9 x: [. Y) y. B- C7 a  |
  ]
! |' G7 m( o" e, {7 D# \$ t
; B3 ^: c& ]+ [4 K! }! {9 H5 R  ;; initialize the global variables that hold patch agentsets. {  |( \7 ]% m& _2 Z# W
  set roads patches with
7 c/ N/ [. a, a: D0 N6 X' ?6 E, m    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) or" Z3 G8 o; J* b
    (floor((pycor + max-pycor) mod grid-y-inc) = 0)], H) p3 n1 w' m/ }% {3 P
  set intersections roads with
& B( {8 z2 q5 H' g0 S3 ?* t2 d: e/ `    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) and: G# J( g9 U, ~+ n
    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]
2 O, ~  ^$ }( ?' H' o& b; [. p$ v
# j+ {- V1 ^& u  ask roads [ set pcolor white ]* d/ k! `+ c; _, R2 V+ {
    setup-intersections% v7 y$ K. l) y
end6 X$ y( d* o  v/ T
其中定义道路的句子,如下所示,是什么意思啊?
# O/ B: K! w- T set roads patches with
+ w9 |" s1 n! V    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) or4 ~  y! p0 r, Z0 a" Q: a' h
    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]
" W- Y+ M$ N) j% q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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