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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 `. v! w$ e. u0 E" Cnetlogo自带的social science--traffic grid这一例子当中,
' I' l. k0 B* Q" `globals
, P& A9 m, W- K7 n, I7 a[
- r. [* e8 Q0 n: `- `5 y) i  grid-x-inc               ;; the amount of patches in between two roads in the x direction
. J% w  u& A4 O* M2 D! R$ J  grid-y-inc               ;; the amount of patches in between two roads in the y direction
: k7 F4 J% E! ~! o5 h- V2 m  acceleration             ;; the constant that controls how much a car speeds up or slows down by if
8 I& \6 ?1 O5 N  Y, {7 @                           ;; it is to accelerate or decelerate$ f* e; _3 G) S# t
  phase                    ;; keeps track of the phase; z3 q* l' P+ H8 b. G4 b; L
  num-cars-stopped         ;; the number of cars that are stopped during a single pass thru the go procedure6 D) g% Y8 L; B; D
  current-light            ;; the currently selected light" R6 ?+ y) G2 o7 m/ j, [
- |$ G: }- H" s! z' r- P# m
  ;; patch agentsets
+ B$ V  v9 B/ K. ]; N1 c! k. ~  intersections ;; agentset containing the patches that are intersections4 |8 j% t4 [/ p0 o- W* z9 L
  roads         ;; agentset containing the patches that are roads
6 z7 H5 q4 j5 ~' q: F: q9 w]( N1 ?& v6 u! c5 G
( |, c! W8 L5 M3 v) \- l) u6 A
turtles-own
' r1 s) \- ~( [[& b3 V1 B) w5 ?+ K* f' H+ }' G0 [0 Z
  speed     ;; the speed of the turtle
) d! U9 M* A' Q. E  up-car?   ;; true if the turtle moves downwards and false if it moves to the right: M- A* a5 y  {+ w* K! ]! y
  wait-time ;; the amount of time since the last time a turtle has moved
# C, Z3 Y1 F; b' C]
% F  P6 O& a9 y' N+ s4 X6 t/ V  K5 I" {0 r3 Z* q
patches-own
1 q( P# ?, `4 Q' c0 y% _[
# w4 M1 v  R- {8 ]& i  intersection?   ;; true if the patch is at the intersection of two roads8 ?) X+ b( Q) R1 q
  green-light-up? ;; true if the green light is above the intersection.  otherwise, false.( j4 M" c  t! ]7 A% T! v
                  ;; false for a non-intersection patches.( x8 D+ b) O/ w( G* c/ h  w' p
  my-row          ;; the row of the intersection counting from the upper left corner of the
/ \6 n7 v- T) Y! A                  ;; world.  -1 for non-intersection patches.8 x- ]- Z) P8 [. `0 |6 e0 B
  my-column       ;; the column of the intersection counting from the upper left corner of the( @+ i) `1 K; n' R5 M" K  s6 `% v
                  ;; world.  -1 for non-intersection patches.
) b; j. G8 b2 e1 n1 ^& |* H" o  my-phase        ;; the phase for the intersection.  -1 for non-intersection patches.
/ B$ H1 h6 V; j) m- H; d  auto?           ;; whether or not this intersection will switch automatically." e: j' L; d  A! x3 z/ j7 Q! T
                  ;; false for non-intersection patches.5 t6 h$ A; _9 a) `3 o( C; _5 ^
]" \' f& v- y6 {& J

" B" R: @: b! y& S6 j. s0 b
5 O" U% Q1 s9 R;;;;;;;;;;;;;;;;;;;;;;
4 o( u1 d: w* m, x; t;; Setup Procedures ;;, _  f; E, d4 P! q) A/ s8 e' x- e
;;;;;;;;;;;;;;;;;;;;;;/ H  O0 \" ]: e4 Y

% k7 W( x$ a3 y! ]2 U, M- U;; Initialize the display by giving the global and patch variables initial values.
8 A1 y5 c+ n( A9 [;; Create num-cars of turtles if there are enough road patches for one turtle to
7 w# L) R, J. E( f1 R;; be created per road patch. Set up the plots.
& v; ]" E! Z! `to setup9 @3 O/ ?( l4 f  ~
  ca
' H# U. ?, U3 r% v0 B( F) G& L  w* X  setup-globals
! T1 a3 C" Z6 z$ \7 c9 k; U5 W
  ;; First we ask the patches to draw themselves and set up a few variables
  Q( D. D4 D( j! V5 C- U+ |  setup-patches4 [% D: X+ G+ i' |# Y+ G* l
  make-current one-of intersections
/ d7 ]* K9 r+ |. }  label-current4 A: Y. H& F: i7 j3 P. j
: E. F  G7 X& J9 h' c2 X$ k) |
  set-default-shape turtles "car"# h# V1 g0 b: q2 [: \4 V
3 X* e* M! G  S; u$ z; J
  if (num-cars > count roads)8 A3 R/ c5 z3 ^# I) E5 ?
  [9 F& }- q$ n8 x+ v; q: a9 _" `
    user-message (word "There are too many cars for the amount of "
& f, k# D5 N, @  K/ {& T) S4 {                       "road.  Either increase the amount of roads ": r9 p& d3 v& D
                       "by increasing the GRID-SIZE-X or "
1 |$ M; F' D) Q+ v! H0 a- O1 ^9 L                       "GRID-SIZE-Y sliders, or decrease the "& ^- w& j7 ^; e' c6 G* v2 j) R
                       "number of cars by lowering the NUMBER slider.\n"
7 y% ?! \- p% |0 r                       "The setup has stopped.")
, `; S* Y6 }( V: b: \    stop
  i* m7 M  [' B# R# }( S" y  ]
9 Y% W% }( A5 `6 q$ b" f1 E- I6 }
, T* W, B7 o1 s3 U( y  ;; Now create the turtles and have each created turtle call the functions setup-cars and set-car-color
% U; R' ?/ b: y7 v+ x) s7 T  crt num-cars9 H2 }+ c% n4 \. N2 l/ ^
  [
. u) n! _+ p+ O1 m2 M$ C: F    setup-cars
0 f+ }+ ~) E6 b0 c    set-car-color3 h- R7 P) \% q* h9 g
    record-data
: j- I6 h1 |  F& E, m& a  ]$ B1 C/ h* ?7 j9 U( k' D
# X1 @7 u2 w  T4 I
  ;; give the turtles an initial speed% I8 b6 |3 ?9 e
  ask turtles [ set-car-speed ]
. u2 P8 |0 q1 T* k9 y0 M$ h& V
* Z  ^' m3 w* |/ c  reset-ticks1 i! v2 e! B( Z7 j
end
  @- ^6 {  d% I- {8 i/ s0 Y) w3 v3 ?- l' e
;; Initialize the global variables to appropriate values3 ?1 E" R# @" |- x! o
to setup-globals
, s6 z* c+ I. D7 D3 z$ z$ m  set current-light nobody ;; just for now, since there are no lights yet5 _( }2 }, p/ R2 g4 O5 N% ]
  set phase 0
, A( Q/ Y! Z2 i  set num-cars-stopped 0
9 F* B9 M5 ]  \/ A. J  set grid-x-inc world-width / grid-size-x
" o, V3 l$ t1 E* f! s! r* M2 u  set grid-y-inc world-height / grid-size-y, }0 H5 |% B1 x3 k. Y  Q- M
* w' \/ Q) T1 K! {2 y4 b6 P
  ;; don't make acceleration 0.1 since we could get a rounding error and end up on a patch boundary9 K" V% L0 @1 h& I5 S: h' G
  set acceleration 0.099
; z) O2 k9 L& W! A: r# y% dend, i, |; V! T/ _. |: d  b
, }! l  k9 |( g) x
;; Make the patches have appropriate colors, set up the roads and intersections agentsets,
: A6 i3 ~/ m3 I;; and initialize the traffic lights to one setting! B9 K+ @6 u# r$ E: Y' k
to setup-patches
8 k' ~- J! s1 Q# _7 l, u  ;; initialize the patch-owned variables and color the patches to a base-color
. V5 _6 `& K! `8 z# A' ^. G  ask patches
7 R( H: \- F/ H8 f7 `9 F4 U' O. X  [% A3 k+ Z$ W2 m1 p. h
    set intersection? false4 J! J" K9 _+ u8 R- G' X
    set auto? false' n- s! G4 }0 p, i! F
    set green-light-up? true" Z% }% E7 {, W
    set my-row -1
: k* u2 f6 i. ^  X4 r: X: O    set my-column -1# _% r7 F  R) o& \
    set my-phase -1% A! F; J# G2 d$ X7 |: s
    set pcolor brown + 36 v) I- k+ r7 U- D. M7 ]
  ]
$ U$ D" S5 h. m* Z5 {' P- F" b5 p6 k6 A6 c8 d! v' J7 T1 b/ X$ T
  ;; initialize the global variables that hold patch agentsets6 o! V. I% s( D* K- Z# A
  set roads patches with0 i- n  i! j2 T( a4 A* c: C
    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) or
4 x5 g$ s2 {' s% c, l    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]/ _$ e6 n& ]1 H: I4 |, W# f
  set intersections roads with
  a& ]* N( `7 F    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) and
% M3 U1 @2 k' M: u3 V    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]
) R6 K: L+ u( y6 U6 U5 ^  ^7 [; [1 R% M# z; w0 T
  ask roads [ set pcolor white ]
2 m5 ]8 Z8 m2 j  m/ c# |1 z/ B4 H    setup-intersections
- \7 }" \# m1 W4 \end
' V) f: J" N( N' o: H+ A其中定义道路的句子,如下所示,是什么意思啊?
( N1 I. @9 u4 e; l  m. J8 Q set roads patches with
( P" Z% Z: i7 D, g. o3 R    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) or
6 @9 _) J) V  _0 c- E% m$ h    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]: L/ O- Z! P8 j+ C# ], ]
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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