[Top][All Lists]
[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index]
[O] [PATCH] Lookup functions for tables
From: |
Jarmo Hurri |
Subject: |
[O] [PATCH] Lookup functions for tables |
Date: |
Wed, 19 Sep 2012 19:48:25 +0300 |
User-agent: |
Gnus/5.13 (Gnus v5.13) Emacs/23.3 (gnu/linux) |
* lisp/org-table.el: added functions org-lookup-first and
org-lookup-last
* doc/org.texi: documented the use of lookup functions
TINYCHANGE
---
doc/org.texi | 88 +++++++++++++++++++++++++++++++++++++++++++++++++++-
lisp/org-table.el | 10 ++++++
2 files changed, 96 insertions(+), 2 deletions(-)
diff --git a/doc/org.texi b/doc/org.texi
index e183969..fc7d9dd 100644
--- a/doc/org.texi
+++ b/doc/org.texi
@@ -2399,6 +2399,7 @@ formula, moving these references by arrow keys
* Formula syntax for Lisp:: Writing formulas in Emacs Lisp
* Durations and time values:: How to compute durations and time values
* Field and range formulas:: Formula for specific (ranges of) fields
+* Lookup functions:: Lookup functions for searching tables
* Column formulas:: Formulas valid for an entire column
* Editing and debugging formulas:: Fixing formulas
* Updating the table:: Recomputing all dependent fields
@@ -2729,7 +2730,7 @@ example above).
Negative duration values can be manipulated as well, and integers will be
considered as seconds in addition and subtraction.
address@hidden Field and range formulas, Column formulas, Durations and time
values, The spreadsheet
address@hidden Field and range formulas, Lookup functions, Durations and time
values, The spreadsheet
@subsection Field and range formulas
@cindex field formula
@cindex range formula
@@ -2785,7 +2786,90 @@ can also be used to assign a formula to some but not all
fields in a row.
Named field, see @ref{Advanced features}.
@end table
address@hidden Column formulas, Editing and debugging formulas, Field and range
formulas, The spreadsheet
address@hidden Lookup functions, Column formulas, Field and range formulas, The
spreadsheet
address@hidden Lookup functions
address@hidden lookup functions in tables
address@hidden table lookup functions
+
+Org has two predefined Emacs Lisp functions for lookups in tables.
address@hidden @code
address@hidden (org-lookup-first val search-list return-list &optional
predicate)
address@hidden org-lookup-first
+Searches for the first element @code{el} in list @code{search-list} for which
address@hidden
+(predicate val el)
address@hidden lisp
+is @code{t}; returns a value from the corresponding
+position in list @code{return-list}. The default @code{predicate} is
address@hidden
address@hidden (org-lookup-last val search-list return-list &optional predicate)
address@hidden org-lookup-last
+Similar as @code{org-lookup-first} above, but searches for the @i{last}
element for which the predicate is
address@hidden
address@hidden table
+
+The examples below illustrate searches inside a single table. In real-world
+applications, the searched data is often in a different table and is accessed
+by remote references.
+
+The first example contains the searched data in the first and the second
+column. The lookup is performed in column 5, where the year corresponding to
+the percentage in column 4 is searched. Notice that an error is returned if
+the lookup is unsuccessful.
address@hidden
address@hidden
+ | year | percentage | | percentage | year |
+ |------+------------+---+------------+--------|
+ | 2009 | 12.2 | | 14.3 | 2010 |
+ | 2010 | 14.3 | | 19.4 | 2012 |
+ | 2011 | 14.3 | | 11.5 | #ERROR |
+ | 2012 | 19.4 | | | #ERROR |
+ #+TBLFM: $5='(org-lookup-first $4 '(@@2$2..@@>$2) '(@@2$1..@@>$1));N
address@hidden group
address@hidden example
+
+The second example illustrates standard use of lookups for teachers. The
+first two columns contain a grading table. The fourth and the fifth column
+contain student names and their marks, and the last column contains the
+results of doing a lookup for the appropriate grade. Notice the use of
address@hidden, the predicate @code{>=} and the use of the @code{L}
+flag for literal interpolation of table values.
address@hidden
address@hidden
+ | lower bound | grade | | student | marks | grade |
+ |-------------+-------+---+---------+-------+-------|
+ | 0 | D | | X | 33 | A |
+ | 10 | C | | Y | 5 | D |
+ | 20 | B | | Z | 10 | C |
+ | 30 | A | | W | 22 | B |
+ #+TBLFM: $6='(org-lookup-last $5 '(@@2$1..@@>$1) '(@@2$2..@@>$2) '>=);L
address@hidden group
address@hidden example
+
+In the previous examples the searched ranges were one-dimensional (single
+columns). Because two-dimensional ranges are converted to one-dimensional
+vectors in Lisp expressions, it is also possible to search true
+two-dimensional ranges. The example below does a lookup in the two first
+columns for values whose distance from @code{search key} is at most 1.
address@hidden
address@hidden
+#+BEGIN_SRC emacs-lisp
+(defun my-p (val1 val2)
+ (<= (abs (- val1 val2)) 1))
+#+END_SRC
+
+#+RESULTS:
+: my-p
+
+| group 1 | group 2 | | search key | result |
+|---------+---------+---+------------+--------|
+| 22 | 12 | | -9 | -8 |
+| -8 | 11 | | 23 | 22 |
+#+TBLFM: $5='(org-lookup-first $4 '(@@2$1..@@>$2) '(@@2$1..@@>$2) 'my-p);N
address@hidden group
address@hidden example
+
address@hidden Column formulas, Editing and debugging formulas, Lookup
functions, The spreadsheet
@subsection Column formulas
@cindex column formula
@cindex formula, for table column
diff --git a/lisp/org-table.el b/lisp/org-table.el
index 37889af..174fe59 100644
--- a/lisp/org-table.el
+++ b/lisp/org-table.el
@@ -4826,6 +4826,16 @@ list of the fields in the rectangle ."
(org-table-get-range (match-string 0 form) tbeg 1))
form)))))))))
+(defmacro org-lookup-function (name-str from-end-p)
+ `(defun ,(intern (format "org-lookup-%s" name-str)) (val search-list
return-list &optional predicate)
+ "Searches for the element el in list search-list for which
+(predicate val el) is t; returns a value from the corresponding
+position in list return-list. The default predicate is equal."
+ (let ((p (if (eq predicate nil) 'equal predicate)))
+ (nth (position val search-list :test p :from-end ,from-end-p)
return-list))))
+(org-lookup-function "first" nil)
+(org-lookup-function "last" t)
+
(provide 'org-table)
;;; org-table.el ends here
--
1.7.7.6
- [O] [PATCH] Lookup functions for tables,
Jarmo Hurri <=
Re: [O] [PATCH] Lookup functions for tables, Achim Gratz, 2012/09/19