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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。1 d. J( b. M) K; Z- s0 O
netlogo自带的social science--traffic grid这一例子当中,+ W  w; |$ |( L7 f% s
globals
. h& b& f5 _  f4 ^* {1 c[8 D" a. i7 N! k# f3 o) @6 m, U
  grid-x-inc               ;; the amount of patches in between two roads in the x direction
. t$ J! |5 R5 B" ?  grid-y-inc               ;; the amount of patches in between two roads in the y direction/ z1 }/ \; ^3 b% |5 I
  acceleration             ;; the constant that controls how much a car speeds up or slows down by if# {6 Z  F$ ^6 [$ d$ i4 p5 g
                           ;; it is to accelerate or decelerate
/ x% O1 m7 z% Q/ F! Z& f  phase                    ;; keeps track of the phase
, a' X7 A- E) O- g4 s  num-cars-stopped         ;; the number of cars that are stopped during a single pass thru the go procedure8 J4 O+ C% T2 Z9 w" y
  current-light            ;; the currently selected light
& U! }! `  |7 Q  ?6 y/ T/ Y
' l& c5 g/ @9 d$ ^* u  ;; patch agentsets
8 |9 r2 v; [# |  intersections ;; agentset containing the patches that are intersections
6 d% n3 z: ^4 G; c  R  roads         ;; agentset containing the patches that are roads3 n3 ?4 P1 n! h! B
]
6 c. j8 h" y2 ^$ t5 X5 m' a1 f7 ?6 B  H2 T3 C* u- Q' _% [
turtles-own
& J: D8 a$ z# X8 Y[
7 X. a' z' a. s  speed     ;; the speed of the turtle- s* `0 g: m- ]
  up-car?   ;; true if the turtle moves downwards and false if it moves to the right5 a& u( F" r: Z- i, H" L
  wait-time ;; the amount of time since the last time a turtle has moved
' A+ H1 B9 ]" a# `' S]
, u) T0 f$ |9 P* E) y* p
8 c. [$ M5 T3 d7 p5 |8 _0 \, Ppatches-own; D1 \1 ?; E- d9 w
[
% o1 T- z: Z- {4 {1 b* `* u/ _  intersection?   ;; true if the patch is at the intersection of two roads4 [% T* c& P) P" b5 j: I
  green-light-up? ;; true if the green light is above the intersection.  otherwise, false.
' S8 P" E, V: C0 Y                  ;; false for a non-intersection patches.
+ ~8 Y- A3 |, j( Y& W9 E  my-row          ;; the row of the intersection counting from the upper left corner of the: M# ]  C: s5 G8 Q
                  ;; world.  -1 for non-intersection patches.' W( t; b' T3 |% ~
  my-column       ;; the column of the intersection counting from the upper left corner of the; t9 a7 I" q3 r- y. s
                  ;; world.  -1 for non-intersection patches.
) @4 w1 a& {- }  my-phase        ;; the phase for the intersection.  -1 for non-intersection patches.: s* a' Q! H0 |4 {
  auto?           ;; whether or not this intersection will switch automatically.
1 I" A  x) }5 ^: @7 U5 }2 u+ r/ G                  ;; false for non-intersection patches.
' A! [) A2 g; L* k1 O- F) `]
2 |. N& j% W, W$ b: X& `" k: d% y5 u% P1 p2 R3 f7 l- r
$ a, `' v3 {4 ^- C
;;;;;;;;;;;;;;;;;;;;;;6 @- ]3 \5 D: J" t+ b# u
;; Setup Procedures ;;
7 A7 D& l# q7 [. y;;;;;;;;;;;;;;;;;;;;;;2 F/ v5 Q" U4 m0 }( `" ~( f9 g2 c
6 P' D6 _9 P) Y; T$ {, H
;; Initialize the display by giving the global and patch variables initial values.: T, K# M! ~1 v$ V* F
;; Create num-cars of turtles if there are enough road patches for one turtle to$ d/ \4 V- ^3 W6 D- M
;; be created per road patch. Set up the plots.1 j/ C' X% {  N- ]# Q, e9 ^7 r, S* z* t
to setup2 F7 @1 ~" F- L8 H4 d
  ca
: [  E2 H4 |# G7 [: K8 M  setup-globals
! g& r: P# X9 b. l* T5 ^9 @1 @/ |3 f5 A6 s
  ;; First we ask the patches to draw themselves and set up a few variables: n1 x* Q+ b9 f9 y+ y  {! f
  setup-patches9 m: K) y" \6 |/ p8 s. y/ U2 M. j
  make-current one-of intersections0 _. j, Q9 k  f
  label-current4 T* L, c0 P  T4 [; v/ E

. ~- k9 x) y3 j( t( N  set-default-shape turtles "car"
/ S9 }- w4 L2 O4 e, j$ B9 [' `3 R  K4 H( f3 k
  if (num-cars > count roads)
4 W0 c$ a$ p! e$ O' v7 [" {  N  [
* m; m8 M6 B, H& s. m3 D: C    user-message (word "There are too many cars for the amount of ". j4 @: P; Z- \/ M4 d
                       "road.  Either increase the amount of roads "
8 _$ j: C# F- l- f6 j. f                       "by increasing the GRID-SIZE-X or "9 W) o% b4 f# a8 i
                       "GRID-SIZE-Y sliders, or decrease the "# N2 I$ J$ P0 Y: e( P; n6 U, v+ }1 j
                       "number of cars by lowering the NUMBER slider.\n"
  a) `" x* t0 k9 n. n                       "The setup has stopped.")/ @6 B' a1 _. m2 d8 T. D& A% l2 d
    stop, L* l+ G; Y* W0 y) U; K
  ]+ |  w* Z9 d# i3 M/ F" k
! Z& ]! ?7 l5 v4 G, n; g
  ;; Now create the turtles and have each created turtle call the functions setup-cars and set-car-color
. w, p& n2 i% m6 c" v% b! M  crt num-cars
4 @" J; l2 V5 W; t4 M  [: t" K2 F( n) K  _
    setup-cars
* y3 k1 \# d. Q: C3 U& C    set-car-color
9 L4 \4 L$ L. N; B1 p' R) }1 u* v    record-data
5 K3 m- U& L7 g/ I+ x  ]# z* U; a) b$ J

5 W6 [% |; ?0 ]$ @0 C) j* D  ;; give the turtles an initial speed
& `( \6 x: M* b: Z; X( F  ask turtles [ set-car-speed ]
2 Y% N3 V% S: Z- G- W% R1 |' ~3 Y: e7 e8 q2 _  \! g) {+ @  O
  reset-ticks8 u7 o! w5 V) a
end
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;; Initialize the global variables to appropriate values; m$ t: d6 Z& ~) Q
to setup-globals7 h$ o* T( |, r% w" t: C8 z' G
  set current-light nobody ;; just for now, since there are no lights yet
% b5 h8 ?' O8 E. R  set phase 0
& a2 q6 a) ]- N+ h  S: {8 R  set num-cars-stopped 0
0 B+ l6 t6 g; v3 ~( s8 d. A' d) K  set grid-x-inc world-width / grid-size-x
& M' r+ _$ {5 B. m+ X  set grid-y-inc world-height / grid-size-y$ F( {4 O/ @1 F9 ?6 Y, F

5 T2 M) u* n* i% u8 c  ;; don't make acceleration 0.1 since we could get a rounding error and end up on a patch boundary
' D& r; C5 n/ i: M3 B( y* H  set acceleration 0.099/ u/ ?) j6 s7 A
end0 ~) _- b# V( s- Y4 ]& v1 ?8 G
& t! ?, a% @& R
;; Make the patches have appropriate colors, set up the roads and intersections agentsets,* A4 a3 d8 w9 Q$ o! Q& {9 r
;; and initialize the traffic lights to one setting+ `( L% i, x6 E. t$ p8 p( G
to setup-patches
  I2 C+ H" i7 ?5 k2 v  ;; initialize the patch-owned variables and color the patches to a base-color
/ w3 @0 p9 n$ l  ask patches9 r5 p" R% _8 [& A2 B1 R
  [, W( [; R' d0 Y3 W3 D$ A
    set intersection? false
* E+ m+ m: X  s- h* @; y    set auto? false. V  {6 b$ f2 R' J4 B3 d+ Z3 f
    set green-light-up? true
8 B2 N2 ]2 e3 p& y2 _' {5 k7 K    set my-row -1
) z2 j5 B# B2 [; Q+ e9 o/ C    set my-column -1
4 C$ s1 z. J2 k5 S: _    set my-phase -1
; b- ]' j7 ^/ Z: ?    set pcolor brown + 3" @8 Y/ q3 q- o8 I3 Q
  ]# Q  K% X# e/ N7 T/ Q

( g( m8 |6 e6 s% z8 y$ y  ;; initialize the global variables that hold patch agentsets
0 w5 t8 F$ d  O7 d  i  P1 }! u$ C; Z  set roads patches with
% J4 \: B) Z& I+ X- _    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) or
" f3 `' X. g$ ]/ w. ]) l) P0 u    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]
1 ?$ @3 H  h0 n6 A  set intersections roads with! ]: R+ S5 K$ J6 ^7 @  c* r! ^
    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) and
' Q+ Z7 \2 k) |/ w    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]1 o# U* a. ?5 [

0 X  J; l. F% U; c/ ?  c7 W  ask roads [ set pcolor white ]
8 z. J0 d; O* k$ b6 ~    setup-intersections
2 \4 m3 @+ v( T& |* w) [& c/ Zend
. K0 Y* N5 r: G' i5 ~其中定义道路的句子,如下所示,是什么意思啊?
5 [9 u5 w) W( I- Z3 ]6 E set roads patches with" }  {& R* |' @  e- z! R
    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) or3 r0 P$ m- M  }) m& u% p4 {
    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]
1 Q# y5 ?$ R- R: d& O6 o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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