[gnuastro-commits] master 91aa806d 2/2: Book: manipulate all the table columns with one column arithmetic

[Mohammad Akhlaghi]

branch: master
commit 91aa806dcf5647a43081039343fd96b837e544c3
Author: Sepideh Eskandarlou <sepideh.eskandarlou@gmail.com>
Commit: Mohammad Akhlaghi <mohammad@akhlaghi.org>

    Book: manipulate all the table columns with one column arithmetic
    
    Until now (in the previous commit), a new feature to do repeated operations
    was added in column arithmetic. However, it was not documented!
    
    With this commit, a new box ("cartouche" in Texinfo) is added to the book
    to explain how the users can use the new '$_all' feature.
    
    The text was edited by Mohammad Akhlaghi.
---
 doc/gnuastro.texi | 33 +++++++++++++++++++++++++++++++++
 1 file changed, 33 insertions(+)

diff --git a/doc/gnuastro.texi b/doc/gnuastro.texi
index ce269bb1..be40eca6 100644
--- a/doc/gnuastro.texi
+++ b/doc/gnuastro.texi
@@ -15583,6 +15583,39 @@ Therefore, when your column arithmetic involves the 
@key{$} sign (to specify col
 Otherwise you can use both single or double quotes.
 @end cartouche
 
+
+
+
+@cartouche
+@noindent
+@strong{Manipulate all columns in one call using @key{$_all}}: Usually we 
manipulate one column in one call of column arithmetic.
+For instance, with the command below the elements of the @code{AWAV} column 
will be sumed.
+
+@example
+$ asttable table.fits -c'arith AWAV sumvalue'
+@end example
+
+But sometimes, we want to manipulate more than one column with the same 
expression.
+For example we want to sum all the elements of all the columns.
+In this case we could use the following command (assuming that the table has 
four different @code{AWAV-*} columns):
+
+@example
+$ asttable table.fits -c'arith AWAV-1 sumvalue' \
+                      -c'arith AWAV-2 sumvalue' \
+                      -c'arith AWAV-3 sumvalue' \
+                      -c'arith AWAV-4 sumvalue'
+@end example
+
+To avoid repetition and mistakes, instead of using column arithmetic many 
times, we can use the @code{$_all} identifier.
+When column arithmetic confronts this special string, it will repeat the 
expression for all the columns in the input table.
+Therefore the command above can be written as:
+
+@example
+$ asttable table.fits -c'arith $_all sumvalue'
+@end example
+
+@end cartouche
+
 Alternatively, if the columns have meta-data and the first two are 
respectively called @code{AWAV} and @code{SPECTRUM}, the command above is 
equivalent to the command below.
 Note that the character `@key{$}' is no longer necessary in this scenario 
(because names will not be confused with numbers):