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The Library of Babel

Introduction

The Library of Babel is an extensible collection of ready-made and easily-shortcut-callable source-code blocks for handling common tasks. Org-babel comes pre-populated with the source-code blocks located in this file. It is possible to add source-code blocks from any org-mode file to the library by calling (org-babel-lob-ingest "path/to/file.org").

This file is included in worg mainly less for viewing through the web interface, and more for contribution through the worg git repository. If you have code snippets that you think others may find useful please add them to this file and contribute them to worg.

The raw Org-mode text of this file can be downloaded at library-of-babel.org

Simple

A collection of simple utility functions

  input

File I/O

reading and writing files

Read the contents of the file at file. The :results vector and :results scalar header arguments can be used to read the contents of file as either a table or a string.

  (if (string= format "csv")
      (with-temp-buffer
        (org-table-import (expand-file-name file) nil)
        (org-table-to-lisp))
    (with-temp-buffer
      (insert-file-contents (expand-file-name file))
      (buffer-string)))

Write data to a file at file. If data is a list, then write it as a table in traditional Org-mode table syntax.

  (flet ((echo (r) (if (stringp r) r (format "%S" r))))
    (with-temp-file file
      (case (and (listp data)
                 (or ext (intern (file-name-extension file))))
        ('tsv (insert (orgtbl-to-tsv data '(:fmt echo))))
        ('csv (insert (orgtbl-to-csv data '(:fmt echo))))
        (t    (org-babel-insert-result data)))))
  nil

remote files

json

Read local or remote file in json format into emacs-lisp objects.

  (require 'json)
  (cond
   (file
    (with-temp-filebuffer file
      (goto-char (point-min))
      (json-read)))
   (url
    (require 'w3m)
    (with-temp-buffer
      (w3m-retrieve url)
      (goto-char (point-min))
      (json-read))))
Google docs

The following code blocks make use of the googlecl Google command line tool. This tool provides functionality for accessing Google services from the command line, and the following code blocks use googlecl for reading from and writing to Google docs with Org-mode code blocks.

read a document from Google docs

The google command seems to be throwing "Moved Temporarily" errors when trying to download textual documents, but this is working fine for spreadsheets.

  (let* ((file (concat title "." format))
         (cmd (format "google docs get --format %S --title %S" format title)))
    (message cmd) (message (shell-command-to-string cmd))
    (prog1 (if (string= format "csv")
               (with-temp-buffer
                 (org-table-import (shell-quote-argument file) '(4))
                 (org-table-to-lisp))
             (with-temp-buffer
               (insert-file-contents (shell-quote-argument file))
               (buffer-string)))
      (delete-file file)))

For example, a line like the following can be used to read the contents of a spreadsheet named num-cells into a table.

#+call: gdoc-read(title="num-cells"")

A line like the following can be used to read the contents of a document as a string.

#+call: gdoc-read(title="loremi", :format "txt")
write a document to a Google docs

Write data to a google document named title. If data is tabular it will be saved to a spreadsheet, otherwise it will be saved as a normal document.

  (let* ((format (if (listp data) "csv" "txt"))
         (tmp-file (make-temp-file "org-babel-google-doc" nil (concat "." format)))
         (cmd (format "google docs upload --title %S %S" title tmp-file)))
    (with-temp-file tmp-file
      (insert
       (if (listp data)
           (orgtbl-to-csv
            data '(:fmt (lambda (el) (if (stringp el) el (format "%S" el)))))
         (if (stringp data) data (format "%S" data)))))
    (message cmd)
    (prog1 (shell-command-to-string cmd) (delete-file tmp-file)))

example usage

#+source: fibs
#+begin_src emacs-lisp :var n=8
  (flet ((fib (m) (if (< m 2) 1 (+ (fib (- m 1)) (fib (- m 2))))))
    (mapcar (lambda (el) (list el (fib el))) (number-sequence 0 (- n 1))))
#+end_src

#+call: gdoc-write(title="fibs", data=fibs(n=10))

Plotting code

R

Plot column 2 (y axis) against column 1 (x axis). Columns 3 and beyond, if present, are ignored.

plot(data)
1 2
2 4
3 9
4 16
5 25 
nil

Gnuplot

Org reference

headline references 

  (save-excursion
    (when file (get-file-buffer file))
    (org-open-link-from-string (org-make-link-string headline))
    (save-restriction
      (org-narrow-to-subtree)
      (buffer-string)))

Tables

LaTeX Table export

booktabs

This block can be used to wrap a table in the latex booktabs environment, it takes the following arguments – all but the first two are optional.

arg description
table a reference to the table
align optional alignment string
env optional environment, default to "tabular"
width optional width specification string 
  (flet ((to-tab (tab)
                 (orgtbl-to-generic
                  (mapcar (lambda (lis)
                            (if (listp lis)
                                (mapcar (lambda (el)
                                          (if (stringp el)
                                              el
                                            (format "%S" el))) lis)
                              lis)) tab)
                  (list :lend " \\\\" :sep " & " :hline "\\hline"))))
    (org-fill-template
     "
  \\begin{%env}%width%align
  \\toprule
  %table
  \\bottomrule
  \\end{%env}\n"
     (list
      (cons "env"       (or env "table"))
      (cons "width"     (if width (format "{%s}" width) ""))
      (cons "align"     (if align (format "{%s}" align) ""))
      (cons "table"
            ;; only use \midrule if it looks like there are column headers
            (if (equal 'hline (second table))
                (concat (to-tab (list (first table)))
                        "\n\\midrule\n"
                        (to-tab (cddr table)))
              (to-tab table))))))

longtable

This block can be used to wrap a table in the latex longtable environment, it takes the following arguments – all but the first two are optional.

arg description
table a reference to the table
align optional alignment string
width optional width specification string
hline the string to use as hline separator, defaults to "\\hline"
head optional "head" string
firsthead optional "firsthead" string
foot optional "foot" string
lastfoot optional "lastfoot" string 
  (org-fill-template
   "
  \\begin{longtable}%width%align
  %firsthead
  %head
  %foot
  %lastfoot
  
  %table
  \\end{longtable}\n"
   (list
    (cons "width"     (if width (format "{%s}" width) ""))
    (cons "align"     (if align (format "{%s}" align) ""))
    (cons "firsthead" (if firsthead (concat firsthead "\n\\endfirsthead\n") ""))
    (cons "head"      (if head (concat head "\n\\endhead\n") ""))
    (cons "foot"      (if foot (concat foot "\n\\endfoot\n") ""))
    (cons "lastfoot"  (if lastfoot (concat lastfoot "\n\\endlastfoot\n") ""))
    (cons "table" (orgtbl-to-generic
                   (mapcar (lambda (lis)
                             (if (listp lis)
                                 (mapcar (lambda (el)
                                           (if (stringp el)
                                               el
                                             (format "%S" el))) lis)
                               lis)) table)
                   (list :lend " \\\\" :sep " & " :hline hline)))))

Elegant lisp for transposing a matrix.

1 2 3
4 5 6 
  (apply #'mapcar* #'list table)
1 4
2 5
3 6

Misc 

a
a + b