Getting latitude/longitude in Degree Minute Second (DMS) using QGIS Field Calculator

Question

I have come up with the following expression to convert 5.1234 to 5°7'24.24"

toint($x) || '° ' || toint((($x) - toint ($x))*60) || '`' || substr((tostring(((($x) - toint($x))*60) - toint((($x) - toint($x))*60))*60), 1, 5) || '"'

Here’s the problem: for some points such as 5.1234, it works. But for others, it doesn’t. I suspect the problem is the integer conversion which round up the decimal figures instead of truncating it.

Is there any other option?

Answer 1

Nowadays there is a native function to_dms() for this intent included in the expression calculator.

Now, you can simply run to_dms(5.1234, 'x', 2). A capture of the current doc can be seen below

Answer 2

I like the expression you've put together - probably no solution in QGIS 1.8, but in QGIS 1.9-dev there's a floor() rounding function which rounds down. For D°M'S'':

(CASE WHEN $x < 0 THEN '-' ELSE '' END) || floor (abs($x)) || '° ' || floor(((abs($x)) - floor (abs($x))) * 60) ||'\'' || substr( (tostring((((abs($x)) - floor (abs($x))) * 60) - floor(((abs($x)) - floor (abs($x))) * 60)) * 60),1,5) || '"'

Note the escaped apostrophe (\').

For D°M.MMM':

(CASE WHEN $x < 0 THEN '-' ELSE '' END) || floor (abs($x)) || '° ' || ((abs($x) - floor(abs($x))) * 60) ||'\''

To limit the number of displayed decimal minutes, substitute # in the expression below with the number of digits:

(CASE WHEN $x < 0 THEN '-' ELSE '' END) || floor (abs($x)) || '° ' ||  format_number( (abs($x) - floor(abs($x))) * 60, #) ||'\'

Answer 3

The modulo operator can be used to do truncation, but the resulting expression would be very ugly. It is prettier to use string substitution, but unfortunately QGIS doesn't expose any strpos or similar functions. Use regexp_replace($x, '\\..*', '') to get the whole part and regexp_replace($x, '^[0-9]*\\.', '') to get the decimal part. Use toreal instead of toint for calculations with the second expression to make sure there will be no rounding.

Answer 4

I made some changes to the code to get the coordinates in DMS, if necessary. Only adjustments to the EPSG information are needed.

Latitude

(CASE WHEN $y < 0 THEN '-' ELSE '' END) || floor (abs(Y( transform( $geometry, 'EPSG:31983', 'EPSG:4326'))
)) || '°' || floor(((abs(Y( transform( $geometry, 'EPSG:31983', 'EPSG:4326'))
)) - floor (abs(Y( transform( $geometry, 'EPSG:31983', 'EPSG:4326'))
))) * 60) ||'\'' || substr( (tostring((((abs(Y( transform( $geometry, 'EPSG:31983', 'EPSG:4326'))
)) - floor (abs(Y( transform( $geometry, 'EPSG:31983', 'EPSG:4326'))
))) * 60) - floor(((abs(Y( transform( $geometry, 'EPSG:31983', 'EPSG:4326'))
)) - floor (abs(Y( transform( $geometry, 'EPSG:31983', 'EPSG:4326'))
))) * 60)) * 60),1,5) || '"'

Longitude

(CASE WHEN $x < 0 THEN '-' ELSE '' END) || floor (abs(X( transform( $geometry, 'EPSG:31983', 'EPSG:4326'))
)) || '°' || floor(((abs(X( transform( $geometry, 'EPSG:31983', 'EPSG:4326'))
)) - floor (abs(X( transform( $geometry, 'EPSG:31983', 'EPSG:4326'))
))) * 60) ||'\'' || substr( (tostring((((abs(X( transform( $geometry, 'EPSG:31983', 'EPSG:4326'))
)) - floor (abs(X( transform( $geometry, 'EPSG:31983', 'EPSG:4326'))
))) * 60) - floor(((abs(X( transform( $geometry, 'EPSG:31983', 'EPSG:4326'))
)) - floor (abs(X( transform( $geometry, 'EPSG:31983', 'EPSG:4326'))
))) * 60)) * 60),1,5) || '"'