emacs regular expression how to get specific columns

Question

I have the following text file:

Input text file:

<Person FirstName='Steve' LastName='Smith' Phone='555-12345' Title='Mr.' BirthDate='1950-01-01' />

<Person FirstName='Lin' LastName='Dan' Phone='555-12345' Title='Mr.' BirthDate='1950-01-01' />

I want to get the following:

expect output text:

Steve Smith
Lin Dan

Don't forget that if you want to test out Regular Expressions in Emacs, you can use M-x regexp-builder — William Denman
– William Denman, Commented Dec 21, 2013 at 9:59
To add to the great answer by @Andreas Röhler, Emacs might or might not be the right tool for this, depending on the use case. How will this fit into something bigger? Does a command-line tool make more sense? — zck
– zck, Commented Dec 22, 2013 at 2:10

Community · Accepted Answer · 2017-05-23 12:03:44Z

1

You can use a regexp with back references for this:

M-x query-replace-regexp

RET .+?'\([A-Za-z]+\)'.+?'\([A-Za-z]+\)'.+

RET \1 \2

The trick is to write a regexp that matches the whole line, while putting the content that you want to keep into parenthesized groups that you can reference in the output you want to generate.

See also this answer to a similar question for a bit more info about back references and a link to relevant portions of the Emacs manual.

EDIT: A shorter version of the regexp to replace that also works for the example input you gave would be .+?'\(.+?\)'.+?'\(.+?\)'.+.

edited May 23, 2017 at 12:03

CommunityBot

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answered Dec 21, 2013 at 9:41

itsjeyd

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Comments

Andreas Röhler · Accepted Answer · 2013-12-21 11:45:50Z

1

Giving another answer still, being as specific as possible makes regular expressions more reliable. You want the contents of precise slots, so let's use its names:

(defun my-name-slots ()
  (interactive)
  (while (re-search-forward "FirstName='\\([^']+\\)'[ \t]+LastName='\\([^']+\\)'" nil t 1)
    (message "%s %s" (match-string-no-properties 1) (match-string-no-properties 2) )))

As (match-string-no-properties 1) (match-string-no-properties 2) holding the output looked for,

(list ...)

at the end of the function would return it as a list.

edited Dec 21, 2013 at 11:45

answered Dec 21, 2013 at 11:40

Andreas Röhler

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