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I have imported some OS MasterMap data into QGIS 3.2 and have labelled the Cartographic Text dataset. This dataset has a rotation field, populated with various angles of rotation depending where they are to be positioned with relation to roads and buildings. However, when I choose this column under Data Defined Placement, it seems to be rotating the labels in the wrong direction.

Is there a way to tell QGIS to treat the angles differently, as you can in ArcGIS (geographic or arithmetic)?

Sean McVeigh
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  • Is this stored in a database? you can do angle expressions in the expression builder. https://gis.stackexchange.com/questions/279504/align-label-text-using-an-expression – Mapperz Oct 09 '18 at 16:24

1 Answers1

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To use an expression to control label rotation, choose "edit" from the data defined override menu.

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If all of your angles are positive numbers, use this expression to make them negative:

concat('-',  to_real('fieldname'))

If your angles include positive and negative values, use this expression:

 to_real('fieldname') * -1

If your field is already in numerical format you can leave out the to_real() function.

csk
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    i'd also check the field type in the layer properties, if it's a string you may need to convert it to an integer. – Steven Kay Oct 09 '18 at 19:30
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    Thanks @StevenKay, I incorporated your suggestion into my answer. I used to_real() instead of to_int(), in case their angles require decimal place specificity. – csk Oct 09 '18 at 19:45
  • Hi csk. I entered your first expression (concat) and this worked perfectly. Many thanks. – Sean McVeigh Oct 19 '18 at 11:27