org: Formula syntax for Lisp
3.5.3 Emacs Lisp forms as formulas
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It is also possible to write a formula in Emacs Lisp. This can be
useful for string manipulation and control structures, if Calc’s
functionality is not enough.
If a formula starts with an apostrophe followed by an opening
parenthesis, then it is evaluated as a Lisp form. The evaluation should
return either a string or a number. Just as with ‘calc’ formulas, you
can specify modes and a printf format after a semicolon.
With Emacs Lisp forms, you need to be conscious about the way field
references are interpolated into the form. By default, a reference will
be interpolated as a Lisp string (in double-quotes) containing the
field. If you provide the ‘N’ mode switch, all referenced elements will
be numbers (non-number fields will be zero) and interpolated as Lisp
numbers, without quotes. If you provide the ‘L’ flag, all fields will
be interpolated literally, without quotes. I.e., if you want a
reference to be interpreted as a string by the Lisp form, enclose the
reference operator itself in double-quotes, like ‘"$3"’. Ranges are
inserted as space-separated fields, so you can embed them in list or
vector syntax.
Here are a few examples—note how the ‘N’ mode is used when we do
computations in Lisp:
‘'(concat (substring $1 1 2) (substring $1 0 1) (substring $1 2))’
Swap the first two characters of the content of column 1.
‘'(+ $1 $2);N’
Add columns 1 and 2, equivalent to Calc’s ‘$1+$2’.
‘'(apply '+ '($1..$4));N’
Compute the sum of columns 1 to 4, like Calc’s ‘vsum($1..$4)’.
Info Catalog
org: Formula syntax for Calc
org: The spreadsheet
org: Durations and time values