How can I format a column of numbers in an emacs org mode table?

Harry Weston Published at Dev

Harry Weston

I have a table in this form, in emacs org-mode. Please, is there a way to format the numbers in columns 3 and 4 to line the decimal points up vertically?

Note, an aside: I sorted the resulting file using bash sort command, and found that the extra | at the start of each line is counted as column 1, so, for instance the column headed OUTPUT is number 4 in this context.

| CALL  | CHAN   |   OUTPUT |    INPUT | QTHR   | LOCATION       | NGR        | REGION   | CTCSS | KEEPER | Internet |
| GB3AH | RB11   |  433.275 |  434.875 | JO02KP | East Dereham   | TF94300990 | EAST ENG |  94.8 | G8PON  |          |
| GB3AS | RV48   |    145.6 |      145 | IO84LS | Wigton,Cumbria | NY33724123 | N.ENG    |    77 | G4KFN  |          |
| GB3AG | RV58   |  145.725 |  145.125 | IO86ON | Forfar         | NO48904170 | SCOT     |  94.8 | GM1CMF | Echolink |
| GB3AY | RV52   |   145.65 |   145.05 | IO75OR | Dalry          | NS26605190 | SCOT     | 103.5 | GM3YKE |          |
| GB3BA | RB01   |  433.025 |  434.625 | IO87SC | Banchory       | NJ72150255 | SCOT     |    67 | GM1XEA |          |
| GB3BD | RB06   |   433.15 |   434.75 | IO92RA | Ampthill       | TL01303860 | SE ENG   |    77 | G8MGP  |          |
| GB3AA | 23cm   |     1297 |     1291 | IO81RO | Alveston,Avon  | ST62608820 | SW ENG   | 118.8 | G4CJZ  |          |
| GB3AI | RV55   | 145.6875 | 145.0875 | IO91QQ | Amersham       | SU97089767 | SW ENG   |    77 | G0RDI  | Echolink |
| GB3AL | RV59   | 145.7375 | 145.1375 | IO91QP | Amersham       | SU95709550 | SW ENG   |    77 | G0RDI  |          |
| GB3AM | R50-13 |    50.84 |    51.34 | IO91QP | Amersham       | SU95709550 | SW ENG   |    77 | G0RDI  |          |

abo-abo

Here are the steps:

This is an optional one, to make things a bit more visual. C-c } turns on the overlays for row and column numbers. Same combination turns the off. Note that these are not the changes in your buffer, they're just tooltips. You might want to do C-c - on the first line, to see the column numbers.
Move cursor to OUTPUT column and insert a new column with C-S-right.
Your cursor should now be in the new column. Type in $4=$3;%0.3f, i.e. copy the third column to the fourth, and format it as a floating point with 3 precision. Press return, and just one cell will fill in. Press C-u C-c * to recalculate all cells. This can also be done with C-c C-c, with cursor on #+TBLFM: line.
You can remove the old column with C-M-left if you want, and delete the table formula below.

UPDATE:

Thanks to input from @phils, here's the alternative way:

Move your cursor to any number in column 3, e.g. 433.275.
Press C-c =, cursor moves to minibuffer.
Enter $0;%0.3f and press return. Here $0 refers to the current column, $3 would also work if it were column 3.
Either press C-u C-c * anywhere in the document, or move the cursor to #+TBLFM: line and press C-c C-c.
Repeat the same process for column 4.