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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。
0 v& k7 E0 U7 s  Lnetlogo自带的social science--traffic grid这一例子当中,4 o. t4 _" z+ @5 D+ C
globals
+ B4 ~# e- o5 R/ Y. a$ M. C[
; Z( A6 @' c! H- l! Y, }  grid-x-inc               ;; the amount of patches in between two roads in the x direction
& R3 }4 ]0 |1 i3 q/ y2 H  grid-y-inc               ;; the amount of patches in between two roads in the y direction' _. x; A4 A8 _. A2 W
  acceleration             ;; the constant that controls how much a car speeds up or slows down by if4 r+ M" Y! l: L& `# s
                           ;; it is to accelerate or decelerate
% r5 I- G- ]. r; f0 }/ b  phase                    ;; keeps track of the phase# [- I5 Y' E- g
  num-cars-stopped         ;; the number of cars that are stopped during a single pass thru the go procedure
  t- k: u; t7 V- N  current-light            ;; the currently selected light
' b# s0 @+ s7 \$ B7 c- Z2 X9 n4 B3 h+ `+ \4 O$ ?
  ;; patch agentsets0 m" n1 G3 a- E  P0 ^
  intersections ;; agentset containing the patches that are intersections
1 I5 M; t& i9 `$ f# Z  roads         ;; agentset containing the patches that are roads) r% U" d7 g8 b7 o7 p: m  r' H) J- ?& U
]; \5 s+ y4 w2 V2 w: q0 \. }
* M% s  g6 q, a) }3 l: B( N# B
turtles-own8 V, U; z1 X# ^% m! B
[
5 y2 ?6 N( L8 R& H: n) k  speed     ;; the speed of the turtle
2 ^1 @3 u& }9 o  up-car?   ;; true if the turtle moves downwards and false if it moves to the right8 @+ d7 E4 ~: H0 i& i- T
  wait-time ;; the amount of time since the last time a turtle has moved
+ \2 r) o# R% @9 x, k: z" w2 M7 G]5 A) c# W2 B) H, a4 B8 A* F4 n
- k- d: h9 q$ y! y" h# q
patches-own: _4 S1 }0 D( v
[) N3 u2 {6 k0 U; T+ ^( m
  intersection?   ;; true if the patch is at the intersection of two roads# ]% D) W: E; Q- b9 P0 w+ W, k
  green-light-up? ;; true if the green light is above the intersection.  otherwise, false.
& @2 J8 y7 r/ E3 v& L7 ^/ `                  ;; false for a non-intersection patches.
9 k: r/ h# ]. X  my-row          ;; the row of the intersection counting from the upper left corner of the" y2 y0 N3 y" i& y8 C+ e/ @9 S
                  ;; world.  -1 for non-intersection patches.' M  [) {8 i2 i& i' P6 k$ y1 P
  my-column       ;; the column of the intersection counting from the upper left corner of the6 x1 y2 i0 @! O3 N
                  ;; world.  -1 for non-intersection patches.
& Q8 X/ B* I, C. j+ K' s  my-phase        ;; the phase for the intersection.  -1 for non-intersection patches.# Z% {7 |9 e% m6 I
  auto?           ;; whether or not this intersection will switch automatically.# h$ s4 Q) H3 ^7 y
                  ;; false for non-intersection patches.) ~, @4 n3 f9 l/ j6 ?5 Y4 l
]
1 h9 t( `3 u& D) I5 v" }! m: }$ ?/ C( r; e- n0 ?; m0 R* \( S
* A( m+ J- c2 h3 ^, V' |5 T4 p
;;;;;;;;;;;;;;;;;;;;;;! g# }, J& V6 e8 k! R" \; _; d
;; Setup Procedures ;;
$ G% K+ J9 R2 G! n2 l( l# _;;;;;;;;;;;;;;;;;;;;;;
9 U& V  M- \9 y( i% w
+ P( u+ P3 V8 R) p;; Initialize the display by giving the global and patch variables initial values.
1 y# z/ A9 ^# `/ x;; Create num-cars of turtles if there are enough road patches for one turtle to
% W% Q  Z9 o7 i2 o3 S;; be created per road patch. Set up the plots.! H3 X% t# j5 O" z2 U
to setup7 z0 }( f3 U6 v, K/ ]; b+ _3 @
  ca
" g5 n) j7 d# T0 B9 {  setup-globals& m5 N& t0 P0 U$ s2 ~/ i

8 i" |) }+ x7 Y  ;; First we ask the patches to draw themselves and set up a few variables
) j- k8 y' ~# [4 Z  setup-patches
4 C/ `- N% B9 k) h, c' U% t  make-current one-of intersections
4 Z% A* `' J5 ?4 L. _* c4 K  label-current
4 ~- \' L7 ^" L9 z. m
1 U3 p8 n% N6 B" I  W  set-default-shape turtles "car"
/ M! i8 n6 a/ r8 j) t  x3 k0 x2 {' h& k2 Q% Z: e
  if (num-cars > count roads)9 }" r  D# {! |4 @) x( B5 |0 q
  [- [! a# C; p7 S9 W* C# n
    user-message (word "There are too many cars for the amount of "
0 l5 O) T: e( P6 B( T                       "road.  Either increase the amount of roads "
3 ?/ V) w; D# v' [2 o* ~                       "by increasing the GRID-SIZE-X or "$ f6 \& [* E' m
                       "GRID-SIZE-Y sliders, or decrease the "
" X3 J/ [+ z- Q- E7 H8 j+ ~                       "number of cars by lowering the NUMBER slider.\n"
5 M& C4 ~. P" Q  C1 p                       "The setup has stopped.")
. z* M7 S8 ?1 m2 p    stop
. j% U( j9 Q0 ?5 u  X( N8 d  ]
3 n5 I8 D! @# i& R" x
4 {, y& g$ z2 o" y; b, N2 \! f/ S  ;; Now create the turtles and have each created turtle call the functions setup-cars and set-car-color: d8 c% Y$ y5 K! v
  crt num-cars( j  d( B; _- t6 a& Y8 q0 P  o) P
  [
/ i' z: R$ }- i    setup-cars
6 C# t+ F3 N  Y& m* b! f4 t    set-car-color. ^9 h! k7 {. q% u8 X5 N
    record-data2 m( S, E0 s6 c+ a/ _6 d
  ]! q9 k+ ~4 H0 u; \
3 }& \+ _6 Y& {2 \: a& Y% c
  ;; give the turtles an initial speed
, r% @9 z: p( w/ d" d5 K! o& x  ask turtles [ set-car-speed ]
" P0 m! i7 R  O+ ^  I7 t* M1 F; J2 R! y; g: U4 m  s% N
  reset-ticks& w5 ]& u+ ^! I
end1 i& k( P6 d  Y/ K4 N" T' G( a

5 k! B6 {. D  z;; Initialize the global variables to appropriate values
0 x, A3 {$ a3 j$ ito setup-globals
8 U5 u: ~( l7 N0 g1 _  set current-light nobody ;; just for now, since there are no lights yet
* F, k& {: S% k: k7 Q  J  set phase 0
1 \+ I* U) G, V$ z% Z- J$ r  set num-cars-stopped 0) w6 M; U# @6 B' Y1 S" O
  set grid-x-inc world-width / grid-size-x: `7 y' Q$ {( M7 o- W7 M
  set grid-y-inc world-height / grid-size-y
0 S% ~* T: p& ~
9 W' h$ s$ |1 T* @2 N9 j  ;; don't make acceleration 0.1 since we could get a rounding error and end up on a patch boundary
7 h0 l6 W7 {8 q& T6 Y+ Y3 z  set acceleration 0.099! o; p- v: f1 X% `
end7 M' |/ Y4 v9 I! q1 Q

7 m. a7 F& o9 [;; Make the patches have appropriate colors, set up the roads and intersections agentsets,# C+ ?# S$ x( g8 N' {
;; and initialize the traffic lights to one setting  |6 e' c1 G* b$ f7 p, m
to setup-patches
5 w5 r, G7 R2 d9 `7 t- W" ?* n  ;; initialize the patch-owned variables and color the patches to a base-color
/ Y( _3 }' Y, F  g  M2 B  ask patches
' N( Y' u1 P6 O  {5 j, X  [4 s% a  B% c; I1 m
    set intersection? false& |, P! P% r: ~- t) b% N! O
    set auto? false4 C3 v& K* Y5 Y! a( |. u. S# f
    set green-light-up? true
: p! l% W( l$ J& i0 N    set my-row -19 G5 v( n. Y. h
    set my-column -15 J! A1 d) m6 H
    set my-phase -1) }% Y* R; N/ f4 o( I2 \1 m. c
    set pcolor brown + 36 ?. A6 X) l) @9 V7 c
  ]
& W# k0 ?6 A6 ]7 t1 i
; L" J' ?- K2 @  ;; initialize the global variables that hold patch agentsets
# y( A$ W9 O+ l, O$ P3 c  set roads patches with
4 w5 U1 ?7 Q& X- @. w. n    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) or
7 }) d3 t' T! [) i    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]
' j, Z& }5 V! n5 d  set intersections roads with
2 j. H6 m4 l# [4 h    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) and
/ T6 f. g! g+ K/ u9 ?& D4 s5 \. g. y    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]
( X7 E8 R6 i4 T2 r) J9 O) F) a: I$ \
  ask roads [ set pcolor white ]
6 e! d" G! F: C4 {7 r, R0 t1 \3 M3 N# e    setup-intersections* T9 z, k8 b/ S" f, D9 R4 B
end5 P9 z5 ^+ e6 L+ X" U$ i
其中定义道路的句子,如下所示,是什么意思啊?
3 o! q, H$ k$ t set roads patches with* r! U) d! f% ]/ o# G$ G
    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) or! a: Q+ N" ~* W2 b- x0 Y
    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]  f$ }) N2 z/ z7 s0 p- `' ^# T
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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