PAW: Physicist Analysis Workstation

Transcription

1 PAW: Physicist Analysis Workstation What is PAW? A tool to display and manipulate data. Learning PAW See ref. in your induction week notes. Running PAW: 2 Versions:- PAW: 2 windows: A terminal window for command input A graphics window for output PAW++: GUI version A terminal window for command input A terminal window for log output Multiple graphics windows for in/output Same functionality, but PAW++ allows interaction with data points. Using PAW Involves operations on 3 data types:- Vectors: 1, 2 or 3 dimensional arrays Histograms: 1 or 2 dimensional N-tuples: Tables of events Postgraduate Computing Lectures PAW 1

2 PAW: Data Flows ASCII File Vector PAW N-tuple Histogram External data flows but can also create internally Main internal data flows (but all are possible) HBOOK File Multiple open at once Organised into directories Each directory can have multiple versions of same object (n-tuple or histogram) Can duplicate and merge Postgraduate Computing Lectures PAW 2

3 PAW: Vectors Vectors Have character identifier e.g. vec 1, 2 or 3 dim. arrays e.g. vec(10,3) Arbitrary size and number (almost!) Create in memory, Read from disk (can filter) and Write to disk Combine e.g. a = b * c ~ ~ ~ Select subrange e.g. vec(2:5,2) Draw (as histogram bins), Plot (histogram points) and Fit to function Postgraduate Computing Lectures PAW 3

4 Functions PAW: Functions Plot user or built-in functions 1, 2 or 3dimensional Wide range of representations (this is just a few of them!) Postgraduate Computing Lectures PAW 4

5 Histograms PAW: Histograms Have a numeric identifier e.g or 2 dimensional Can associate errors with bins Read from / Write to disk / Create in memory. Combine e.g. A = B * C Select subrange e.g.123(1:20) Wide range of plotting and fitting facilities Postgraduate Computing Lectures PAW 5

6 N-tuples Have numeric identifiers e.g. 123 Record a set of n numbered (1..n) events each with m named attributes:- Two types Row-Wise PAW: N-tuples ******************************************************** * NTUPLE ID= 10 ENTRIES= 3354 CERN Population * ******************************************************** * Var numb * Name * Lower * Upper * ******************************************************** * 1 * CATEGORY * E+03 * E+03 * * 2 * DIVISION * E+01 * E+02 * * 3 * FLAG * E+00 * E+02 * * 4 * AGE * E+02 * E+02 * * 5 * SERVICE * E+00 * E+02 * ******************************************************** Stored as a set of rows Each attribute is a 4-byte floating point Column-Wise Stored as a set of attributes Attributes can be a integer, real or char Fixed or variable length Create in memory, I/O to disk. Merge two or more. Postgraduate Computing Lectures PAW 6

7 PAW: N-tuples (cont) Can plot functions of attributes, e.g. if have attributes x,y plot:- sqrt(x**2+y**2) Can apply cuts on points to plot e.g.:- sin(x)+log(y) z>1.0.and.z<10.0 This is very powerful! Can also Print rows on basis of cuts Masks:- Used to store commonly used cuts Saves time: only computed once Can have 32 masks per n-tuple Can plot in 1, 2 or 3 dimensions, e.g. z%y%x to plot Z v. Y v. X Plotting, PAW generates histograms:- Automatically choosing suitable scales For fine control can define histogram and the plot into that. Scanning: Each entry in n-tuple is processed by user code Postgraduate Computing Lectures PAW 7

8 SIGMA PAW: Programming A system for vector operation e.g:- sigma x=array(200,0#2*pi) sigma s=sin(x) COMIS Create a 200 point vector x running Create a 200 point vector s of sin(x) A FORTRAN interpreter Supports a subset of FORTRAN77 Has access to PAW s internal data structures Can make calls to a wide range of CERNlib routines Allows users to add their own code, without linking, for:- N-tuple plotting and cutting functions Fitting and plotting functions Non-standard operations on internal data structures. Another very powerful feature! Postgraduate Computing Lectures PAW 8

9 PAW: Command Interface Commands Have a tree structure e.g. vector/operations/vscale Can abbreviate if unambiguous e.g. ve/op/vsc or even vsc Case insensitive Built-in help: summary (usage) or detailed (help) Command line recall with arrow keys Can be stored in files as macros. Files have the extension.kumac Complete programming language with:- Local variables Global variables Flow control Argument passing - so that macros can be used like subroutines Embedded data files Typically users develop kumac files as part of their analysis tool set Postgraduate Computing Lectures PAW 9

10 PAW: Graphics Options to Control Appearance Position on screen. Direct plots into tiled zones on the screen Log and linear scales Titles Attributes of graphical elements:- HIGZ Colour Thickness Character font Line type (solid or broken) Is the underlying plotting package Has a wide range of primitives e.g. titles, axes, polylines etc. that can supplement raw plots All graphical output can be stored in files and output as Postscript. Postgraduate Computing Lectures PAW 10