AstroTable - EranOfek/AstroPack GitHub Wiki

Description

Class Hierarchy: Base -> Component -> AstroTable

The AstroTable class is a container for storing and manipulating astronomical tables. The class includes basic functionality. The AstroCatalog class inherits from AstroTable. AstroCatalog inherits from AstroTable. Additional help is available using:

help AstroTable
help AstroTable.AstroTable
% to see this file
open manuals.classes.AstroTable
AstroTable.help

while a list of properties and methods is available by typing AstroTable followed by , or using

methods(AstroTable)

Class properties

  • Catalog - Containing the table data. This can be eithre a matrix, or a table.
  • ColNames - A cell array of column names.
  • ColUnits - A cell array of column units.
  • ColDesc - A cell array of column descriptions.
  • SortByCol - An array of column indices, or a cell array of column names by which the catalog is sorted.
  • IsSorted - A logical indicating if the catalog is sorted.

Constructor

The AstroTable constructor can be used to generate empty objects, or load tables into an AstroTable object. A few examples:

% create a single element AstroTable with an empty Catalog.
AC = AstroTable
% Create a 2x2 AstroTable with an empty Catalog
AC = AstroTable([2 2])
% Created a 1x2 AstroTable. In each catalog store a rand(10,2) matrix
AC = AstroTable({rand(10,2),rand(10,2)})
% THe same as the previous line + set the Column names to 'a' and 'b'
AC = AstroTable({rand(10,2),rand(10,2)},'ColNames',{'a','b'});
% store tables
AC=AstroTable({array2table(rand(10,2))});
% Create an AstCat object (an old version of AstroTable)
A = AstCat;
A(1).Cat=rand(10,2);
A(2).Cat=rand(10,2); A(1).ColCell={'RA','Dec'};
A(1).ColUnits={'rad','rad'};
% read the AstCat object and convert it to AstroTable
AC = AstroTable(A);
% read from a FITS table
AC=AstroTable('asu.fit','HDU',2);

Setters and getters

The setters and getters will set the IsSorted to false when a Catalog is changed. Furthermore, when the ColNames is modified, if the Catalog property contains a table, it will be updated accordingly.

Static methods

  • defaultColNames - Generate a cell array of defalt column names - e.g., {'Var1', 'Var2',...}
  • compareColNames - compare two cell arrays of column names.
  • insertColumn - Insert a single column into a matrix, table, or a cell array.
  • searchSynonym - Find the first appearance of a synonym in a cell array.
  • unitTest - unitTest for the class

Examples

% test the class

AstroTable.unitTest

Methods

General methods

  • sizeCatalog - Return the number o rows and columns in all elements in an AstroTable object.
  • isemptyCatalog - Return true if Catalog data in AstroTable object is empty, otherwise false.
  • deleteCatalog - delete the content of an AstroTable object.
  • array2table - Convert catalog data in AstroTable to table forma.
  • table2array - Convert catalog data in AstroTable to array format

Examples

AT = AstroTable({rand(100,2),rand(50,2)},'ColNames',{'RA','Dec'});
% return the size of the two catalogs in AT
[Nrow, Ncol]=AT.sizeCatalog
% check if each catalog is empty
AT.isemptyCatalog
% delete the second catalog
AT(2).deleteCatalog;
% check if each catalog is empty
AT.isemptyCatalog

Columns information

  • isColumn - Return true if a name is an existing column name in an AstroTable object.
  • colname2ind - Convert column names to column indicet.
  • colind2name - Return column names corresponding to column indices.
  • colnameDict2ind - Given a list of column names, select the first that appear in Table.
  • col2struct - Return structure array with column names in field and index in values.
  • isColIdentical - Check if ColNames in an AstroTable object is identical to another ColNames

Examples

AT = AstroTable({rand(100,2),rand(50,2)},'ColNames',{'RA','Dec'});
% check if RA column exist in each catalog
AT.isColumn('RA')
% colname2ind works on a single element object - return the index of 'Dec'
% column
AT(1).colname2ind('Dec')
% for two column names
AT(2).colname2ind({'Dec','RA'})
% search for the first appearance of a name in column, and return the
% column index (in the example, this is the Dec column)
AT(1).colnameDict2ind({'DECJ2000','Dec2000','Dec'})
% like colname2ind, but for multi element objects
% return a struct array with the column indices
St=AT.col2struct
% compare the column names to a cell array, for each element:
AT.isColIdentical({'a'})
AT.isColIdentical({'RA','Dec'})

Columns and Data retrival and editing

  • getCol - Get a catalog columns by index or names
  • insertCol - Insert columns to AstroTable object
  • replaceColNames - Replace column names in AstroTable object
  • replaceCol - Replace columns in AstroTable
  • deleteCol - Delete columns fron an AstroTable object.

Examples

AT = AstroTable({rand(100,2),rand(50,2)},'ColNames',{'RA','Dec'});
% return the content of the column named 'Dec'
AT(1).getCol('Dec')
% add a new column named 'NewCol to the first element in AT, after the last
% column (i.e., Inf).
AT(1).insertCol(rand(100,1),Inf,'NewCol')
% replace column names {'RA','Dec','NewCol'} with {'RA','Dec','Mag'} at
% positions 1 to 3:
AT(1).replaceColNames([1:3], {'RA','Dec','Mag'})
% delete one or more columns by name or index
AT(1).deleteCol('Mag')
AT.deleteCol({'RA','Dec'})
% now, the two catalogs are empty:
AT.isemptyCatalog

Table Merging

  • merge - Merge table/matrices in multiple AstroTable elements

Examples

AT = AstroTable({rand(100,2),rand(50,2)},'ColNames',{'RA','Dec'});
% merge the two catalogs into one
New = merge(AT)
% add two new columns to the New catalog
New.insertCol(rand(150,2),Inf,{'a','b'})

Table sorting

  • sortrows - Sort AstroTable objects by some column names/indices.
  • flipud - flip up-down all catalogs in AstroTable object (set IsSorted to false)

Examples

AT = AstroTable({rand(100,2),rand(50,2)},'ColNames',{'RA','Dec'});
% check if sorted
AT.IsSorted
% sort by Dec
AT.sortrows('Dec')
% check if sorted
AT.IsSorted
% flip
AT.flipud

Functions on tables

  • funUnary - Apply an unary function to columns of a catalog
  • min - Calculate the min value of all requested columns names/indices. Default is for all columns.
  • max - Calculate the max value of all requested columns names/indices. Default is for all columns.

Examples

AT = AstroTable({rand(100,2),rand(50,2)},'ColNames',{'RA','Dec'});
% min on all columns
% The output is a matrix of size [Number of elements X number of columns]
min(AT)
max(AT(1))

Queries

  • query - Query an AstroTable object
  • queryRange - Query catalog by columns in range (without using eval).

Examples

AT = AstroTable({rand(100,2),rand(50,2)},'ColNames',{'RA','Dec'});
% operate a query string using column names
New = query(AT,'RA>0.1 & Dec<0.2')
AT.sizeCatalog
New.sizeCatalog
% a faster query in range
AT.queryRange('RA',[0.1 0.2])
AT.sizeCatalog
% use multiple ranges
AT.queryRange('RA',[0.1 0.9],'Dec',[0.1 0.9])
AT.sizeCatalog
% value in columns equals some value
AT.queryRange('RA',0.5)
AT.sizeCatalog

Ploting

  • plotFun - Operate a graphical function on AstroTable
  • plot - plot function for AstroTable objects

Examples

AT = AstroTable({rand(100,2),rand(50,2)},'ColNames',{'RA','Dec'});
% plot RA vs. Dec
AT(1).plot({'RA','Dec'},'o')
% overlay both elements on top of each others
AT.plot({'RA','Dec'},'o','MarkerFaceColor',[0.8 0.8 0.8])
% apply a general plotting function on AstroTable:
AT(1).plotFun(@hist,{'RA'})

Conversion to other formats:

  • writeCSV - save the entries from an AstroTable object (or a vector of AT objects) into a single .csv file
% make a list of AstroCatalog files in the current directory:
Files  = dir ( fullfile('./', '**', '*Cat*') );
NData  = numel(Files); Data   = repmat({''}, NData, 1);
       for IData = 1:1:NData
              Data{IData} = fullfile(Files(IData).folder, Files(IData).name);
        end
% make an AstroCatalog object from all the catalog FITS files:
AC = AstroCatalog(Data);
% save all the source entries from all the data files as a single .csv file:
AC.writeCSV('/home/ocs/cat.csv');

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