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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。( M( p) [9 d! B7 V: I
netlogo自带的social science--traffic grid这一例子当中,6 G& `/ B" O9 U; p% c, K7 b6 w, ]
globals
1 f, j' q4 o/ E# v, k# x* W7 N. G[
0 u( N& n( x- w% @- y  grid-x-inc               ;; the amount of patches in between two roads in the x direction# \* S0 M# X" s5 p
  grid-y-inc               ;; the amount of patches in between two roads in the y direction
  w. |/ _% H& E  acceleration             ;; the constant that controls how much a car speeds up or slows down by if
5 e" `+ g: i/ @8 Z& x* ~- q                           ;; it is to accelerate or decelerate. n  ?/ m3 k: N" n" w) e
  phase                    ;; keeps track of the phase' P7 F8 T! O+ Q3 _& j8 K
  num-cars-stopped         ;; the number of cars that are stopped during a single pass thru the go procedure9 J3 M8 y1 d# A' U7 y! y# d, d, c( r
  current-light            ;; the currently selected light
6 |1 p' i: [! r7 J4 w; _2 z  e, e- }& t
  ;; patch agentsets
5 h# f! w+ V8 y+ c  intersections ;; agentset containing the patches that are intersections
# M" k/ P( Q7 d7 P* \, g  roads         ;; agentset containing the patches that are roads
# }: v7 Z$ S" n& q0 t2 o  R6 z7 I; ~]
7 T2 J+ i4 ?# K% b* l0 K! C' N' m+ e7 {% A$ q$ T" X+ l
turtles-own
/ g6 ^" o8 O0 J, f7 y- f' z[! R4 D/ x  e0 M) {
  speed     ;; the speed of the turtle
4 M: X" h! I, N8 R  up-car?   ;; true if the turtle moves downwards and false if it moves to the right' I. u  G4 n5 O0 r( N
  wait-time ;; the amount of time since the last time a turtle has moved
4 o6 a5 Q" i9 @" G- n]+ R* a9 ^; a' N3 x7 V! e" @

, {8 v$ B1 S! {+ Tpatches-own% h  Z, e9 a9 E1 H
[
: j& f1 @  K5 b1 p1 {* z  intersection?   ;; true if the patch is at the intersection of two roads0 w' X/ a+ g; p
  green-light-up? ;; true if the green light is above the intersection.  otherwise, false.; a0 \# f$ ^( a
                  ;; false for a non-intersection patches.
8 z8 f+ }' S9 y: i8 Q/ q( l  my-row          ;; the row of the intersection counting from the upper left corner of the; M7 D4 e. E3 d
                  ;; world.  -1 for non-intersection patches.6 @4 q. o6 q% D$ U/ ?
  my-column       ;; the column of the intersection counting from the upper left corner of the& _7 h4 H/ `8 U6 ~6 Q) U3 }& P. A
                  ;; world.  -1 for non-intersection patches.
! N+ V; L; L, f# I' z% W" z. m" K  my-phase        ;; the phase for the intersection.  -1 for non-intersection patches.: f, w7 [) p7 K+ y+ K
  auto?           ;; whether or not this intersection will switch automatically.3 T3 D# {) k& \4 K
                  ;; false for non-intersection patches.- F# b# O2 M/ A* f
]2 \; k7 I$ J1 E' D" i5 H7 m# B

3 }  b( n8 h3 I! y. n% ?# c& A. [- s' l7 \" z) n" ]5 |. H
;;;;;;;;;;;;;;;;;;;;;;
8 D  B* }" j3 Q8 K;; Setup Procedures ;;8 F' Q- p: \+ M! I( A# g
;;;;;;;;;;;;;;;;;;;;;;6 j3 Y' Y  A1 x8 d& W
4 D* u) z: u, R/ Y, Q1 y
;; Initialize the display by giving the global and patch variables initial values.4 n6 L# j$ D. j
;; Create num-cars of turtles if there are enough road patches for one turtle to8 x9 A  X" a, i% b! y' Q" @
;; be created per road patch. Set up the plots.0 y& Q* w. ]# }1 s
to setup
0 J6 P- a+ U9 a; Q2 X  ca
% f6 E' {% r3 S2 o1 X& j* X  setup-globals% I/ d) j8 o# ]% b+ ~7 X
7 B' s8 Z9 i( f3 p! j
  ;; First we ask the patches to draw themselves and set up a few variables1 p( `' y$ |- z% ^" s" J3 `7 i
  setup-patches
+ P) `# P0 F" F  make-current one-of intersections; y& l# a" _. `
  label-current
8 o! `5 Q2 z4 O. _$ x9 x1 L& d( M) U# s9 s3 Q4 D
  set-default-shape turtles "car"; l$ C* F0 g4 |" o

! X, u( j5 v- c, k  if (num-cars > count roads)
, J! ~0 P4 z! [$ U. [  @, O  [- {' A- X' p% A9 P
    user-message (word "There are too many cars for the amount of "
# B+ k5 \; Y: Q' |                       "road.  Either increase the amount of roads "; f6 g2 r' t2 Z9 L' C: B; x
                       "by increasing the GRID-SIZE-X or ", C. f! D) X  Y2 ?1 `( [
                       "GRID-SIZE-Y sliders, or decrease the "
3 p' f5 K3 [/ Y                       "number of cars by lowering the NUMBER slider.\n"" L$ S$ }% b5 Y* L0 q
                       "The setup has stopped.")2 q: n( }' ^& j# c* f! V
    stop
; [0 ?' f& f$ I  ]2 _% ?/ _* Z2 k1 Z2 C

/ C: w3 p3 @! X  ;; Now create the turtles and have each created turtle call the functions setup-cars and set-car-color/ u3 k% \9 d0 M! X% n
  crt num-cars
( H+ ~5 t8 x* m% s/ x2 _2 `& T  [
1 z6 ~; ^( C5 b4 ]# T. L    setup-cars9 j! Q$ U/ l% ]
    set-car-color
& E6 o3 U8 X  E; p    record-data  @0 b- N& N4 j% \" T
  ]
: \1 z9 [6 x: V; }# L/ I
* b% _" {1 \; C6 |% G  ;; give the turtles an initial speed
1 w! P0 |4 H( }0 `- k+ J  {& o  ask turtles [ set-car-speed ]) e) Y1 f* ?7 \2 X# I- O& w$ @
. \+ Q! ]0 c# J
  reset-ticks$ i# W4 n9 V0 e2 D+ W: S
end- o" A! V* z' ~% |. B' c6 W

; r* j3 b! N; m;; Initialize the global variables to appropriate values
& Q& K9 P6 X6 K/ [- A* {, o$ w! E( c7 Eto setup-globals' ^( v/ y) |4 y& J
  set current-light nobody ;; just for now, since there are no lights yet
  x2 c! e6 V9 i( b  set phase 0* T* @8 O0 `: V9 E9 o
  set num-cars-stopped 0; \( T# n! V0 e; @2 W7 h6 j
  set grid-x-inc world-width / grid-size-x
+ ?3 u( [; a9 t0 ]  set grid-y-inc world-height / grid-size-y: T, _* H2 H) q3 Z# [, L  `* F

- S. {; D" a; G# V  ;; don't make acceleration 0.1 since we could get a rounding error and end up on a patch boundary, T4 ^+ c& \8 `: K$ O; _. [
  set acceleration 0.099
( W* q- J/ \2 jend9 ^. D- D, Q) ?/ V! u5 Y( @
6 {# A7 H" Y0 c# ^. U
;; Make the patches have appropriate colors, set up the roads and intersections agentsets,. b# \9 A$ D8 V+ C3 v
;; and initialize the traffic lights to one setting
9 v6 S! E. p5 ~4 @/ O' jto setup-patches
. E+ R% E* l! ]- _+ M0 U- V  ;; initialize the patch-owned variables and color the patches to a base-color
- h$ [/ S% h- e7 j( f  ask patches3 N' w" P& a" i  D& s: F
  [
2 x9 k, X$ _4 L  R8 r  H7 Q    set intersection? false, w3 X; B6 x8 C2 G8 u6 |$ T0 E) v
    set auto? false
1 K4 o7 c# k) ?3 q5 A' o& E$ K( M    set green-light-up? true
3 ]* d! o3 R' B7 y) U4 J6 E7 v    set my-row -17 ^/ `$ ?, o/ q( L- Q. d
    set my-column -1* y2 X& P3 E; I! s$ [, R* z0 T
    set my-phase -19 s) @5 y: Q3 \; \3 v7 I
    set pcolor brown + 3" F$ l- D( u" k
  ]3 G! e: u. V- e8 m: F4 m0 w
) O' a; U' j! Q8 \3 J3 h) }
  ;; initialize the global variables that hold patch agentsets
  K, E+ l( R. F7 G& _3 A5 j  [  set roads patches with
/ `& i# n0 B! h: y" V; d9 [    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) or
' ?  m0 j" Y0 b    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]
' [; B" q8 g+ k5 m  set intersections roads with
1 ]$ v: }; ~7 d) Y" @; D6 L4 W    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) and( S0 w9 A; u  {! X, z, ]
    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]% y4 S# Y7 C$ ~9 y! ?3 e( V9 N7 Y

( o% b* b) B* {! [; H9 b  ask roads [ set pcolor white ]
3 u7 ?2 e& _. |; c    setup-intersections( f$ ^0 I: N& _. B7 r$ R6 k7 @. U
end: l" C$ Y5 |$ b
其中定义道路的句子,如下所示,是什么意思啊?0 \9 k3 F- x" ?
set roads patches with
; N8 {! {+ U+ @% F1 M) }    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) or
1 ^( k- J2 Y6 `& G! U    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]
( ^7 N( j4 K5 \9 K! S7 U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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