Am 08.05.2012 11:45, schrieb x.pi...@gmail.com:
Hi all.
Is table filtering is implementad in org-mode?
Thanks.
Well, I have done something similar, which includes a few more operations than
filtering.
It uses org-babel and comes as an org-file, which combines code and
documentation.
Hope, this might be useful for you.
with kind regards, Marc-Oliver Ihm
* Table operations --- filter or combine tables
This section within the library of babel provides table operations.
See the documentation just below for details and working examples.
Author : Marc-Oliver Ihm i...@ferntreffer.de
Version : 1.0
** Documentation
*** Introduction
The table operations (currently four) are grouped in two categories:
- Filtering the rows of a single table: keeping or removing
- Combining two tables into one: merging or intersecting
All four operations are demonstrated below.
*** Example tables
To demonstrate we need three tables: upper, lower and keys:
#+name: upper
| 1 | A |
| 3 | C |
| 4 | D |
| 10 | J |
| 2 | B |
#+name: lower
| Position | Letter |
|--+|
|2 | b |
|4 | d |
|5 | e |
|6 | h |
#+name: keys
| Position |
|--|
|1 |
|2 |
|4 |
The tables upper and lower both have two columns and associate a position in
the alphabet with the matching letter. E.g. the row | 1 | A | from table
upper, just states that the letter A comes at position 1 in the alphabet.
Nearly the same is true for table lower, only that it contains lower case
letters. Some of its letters (e.g. b) have counterparts in table upper
(B), some (e.g. e) dont.
The table keys finally, contains keys (i.e. positions within the alphabet),
that can be used to select rows from either table upper or lower.
Note, that tables may have column headings or not.
*** Filtering a table
Keeping rows
Let's say, we want to select the upper-case letters (i.e. rows from the
table upper), that are given in table keys (i.e. the first, second and
fourth letter).
This can be described as filtering table upper and keeping only those rows,
that appear in table keys.
As a babel-call, this reads:
#+call: table-operations-filter-keep(upper,keys)
#+results: table-operations-filter-keep(upper,keys)
| 1 | A |
| 4 | D |
| 2 | B |
,which gives exactly those rows from table upper, that are specified in
keys.
Removing rows
Now, if on the contrary you want to filter table upper to remove any rows,
which are given in table keys:
#+call: table-operations-filter-remove(upper,keys) :colnames yes
#+results: table-operations-filter-remove(upper,keys)
| Position | t2c2 |
|--+--|
|3 | C|
| 10 | J|
,which is the expected result.
Please note, that the call contains the header argument :colnames yes,
which causes the result table to contain the headings Position and
t2c2. These headings are taken from the input-tables upper and
keys. However, as upper does not contain any headings, the heading t2c2
is generated artificially; it stands for table 2 column 2.
If you do not want to have column names in the result table, just leave out
the header argument :colnames yes like in the first example. Note
however, that :colnames no does not give the expected effect.
*** Combining tables
Now, lets have a look at the tables upper and lower alone and see how to
combine them.
Note, that we only look at combining two tables for simplicity, however, all
operations can be easily scaled up to seven tables.
Merging rows
We have two tables, one with upper case letters and one with lower
case. What now, if you want to have only one table, which contains both,
upper and lower case letters ?
You may want to merge them:
#+call: table-operations-combine-merge(upper,lower) :colnames yes
#+results: table-operations-combine-merge(upper,lower)
| Position | t1c2 | Letter |
|--+--+|
|1 | A||
|2 | B| b |
|3 | C||
|4 | D| d |
|5 | | e |
|6 | | h |
| 10 | J||
This result combines both upper and lower case letters and lists them by
their position within the alphabet.
Intersecting rows
If you only want the rows, that are complete (i.e. have both upper and
lower case letters) you may compute the intersection:
#+call: table-operations-combine-intersect(upper,lower)
#+results: table-operations-combine-intersect(upper,lower)
| 2 | B | b |
| 4 | D | d |
,which has only those keys and letters, that appear in both tables.
Note, that we have ommitted the headeragument :colnames yes so that the
result table has no headings.
** Internals
This section is
