[Qgis-user] labelling by attribute

[Andreas Neumann]

Hi Lucas,

Actually we don't just blindly copy "ArcGIS" - not like gvSIG copied the 
UI of ArcView 3. Actually most devs and users do not  have access to 
ArcGIS - because it is quite expensive. The last ArcGIS version I 
personally used was 8.3 or so, several years ago. So please do not ask 
for features because "ArcGIS" has it and do not assume that most people 
on this list know how things work in ArcGIS. Although ArcGIS is very 
powerful, there are already quite a few things you can do in QGIS, but 
not in ArcGIS - but certainly - and even more so - the opposite way. 
Actually we don't care much about ArcGIS - we do our best to satisfy our 
users needs with the limited financial resources we have, probably 
0.00xx percent of what ESRI has available in its budget.

However, I agree with you, that rule-based or categorized labels would 
be very useful to have in QGIS. In fact we know this for a long time 
already - since version 2.0 people have asked for it. But - it is quite 
a lot of work to implement. If you need this, consider sponsoring it or 
start a crowd-funding initiative.

As to your question "how do you know what QGIS 'expect' after the 
'then'". Click on the data-defined drop-down symbol and select 
"Description". A small window opens that tells you the data type, 
description and example. In case of "bold" it expects a 0 (inactive) or 
1 (active). See the two small screenshots attached.

Andreas

On 20.06.2015 09:32, Luca Galuppini wrote:
> @ Fred: thank you for the workaround you have suggested, but i need 
> something "clean" as my project is so much "crowdy" as it is now, 
> duplicating layers or breaking them by attribute is something i would 
> keep as last resource...
>
> @ Tom: this is what i was looking for, i'm not familiar with this kind 
> of expressions (is it SQL?) and surely next versions of qgis need some 
> GUI for this function, even if probably the expression thing grants 
> more flexibility. anyway, how do you know what the program "expects" 
> after the "THEN"? what is the correct argument for bold, or italics, 
> or a different font color?
>
> 2015-06-20 3:20 GMT+02:00 Tom Lennon <tolennon at gmail.com 
> <mailto:tolennon at gmail.com>>:
>
>     Hi Lucas:
>     You can use the "data defined override" to set the text size based
>     on your classes.
>     Use the fancy "E" under Layer Properties > labels > size.
>     The program expects a number which will become the size.
>
>     If the class in your data base is called "class" and it happens to
>     be a number usable as the text size just put "class" in the override.
>
>     If "class" is a ranking number ( like 1 - 6, with 1 being the
>     largest population and 6 the least) then enter 13 - "class" in the
>     override to get 7 for least and 12 for largest "class".
>
>     if "class" is a population number then enter a CASE expression
>     like this:
>     CASE
>     WHEN  "class" > 1000000 THEN  12
>     WHEN  "class" > 750000 AND  "class" < 1000000 THEN  11
>     WHEN  "class" > 500000 AND  "class" < 750000   THEN  10
>     WHEN  "class" > 250000 AND  "class" < 500000   THEN  9
>     WHEN  "class" > 100000 AND  "class" < 250000   THEN  8
>     ELSE     7
>     END
>
>     The overrides can be used to also change font or type style based
>     on data values as well.
>
>
>     On Fri, Jun 19, 2015 at 5:52 PM, Fred Lali <lalifred at gmail.com
>     <mailto:lalifred at gmail.com>> wrote:
>
>         Lucas, just copy the same layer and paste in the same canvas n
>         the label them with different fonts!
>
>
>
>         For God and My Country
>         Consultant in: GIS,Forestry and Environment @ Earth Consult(U)
>         Ltd.
>         CCRP GIS Support-Uganda
>         (The MCKNIGHT Foundation)
>
>         Rotarian at RC. Bweyogerere Namboole
>         Mob: 0772/0752-841118
>         Sent from Lumia Windows phone
>         ------------------------------------------------------------------------
>         From: Luca Galuppini <mailto:luca.galuppini at gmail.com>
>         Sent: ‎20/‎06/‎2015 00:28
>         To: qgis-user at lists.osgeo.org <mailto:qgis-user at lists.osgeo.org>
>         Subject: [Qgis-user] labelling by attribute
>
>         i'm sorry for posting a lot of newbie questions but tutorials
>         are not so clear about this:
>         i have to label a point feature with different font size or
>         style depending on an attribute in the table (for example, i
>         have cities grouped in classes by their importance, and i want
>         the bigger cities to have bigger label size).
>         this is really straight forward in arcgis but i really can't
>         find this option in qgis 2.8.2, at least not in a place when
>         one can find it easily.
>         i expect i should have something similar to symbol by
>         category, but nothing like that is in the label menu...
>
>         _______________________________________________
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>         Qgis-user at lists.osgeo.org <mailto:Qgis-user at lists.osgeo.org>
>         http://lists.osgeo.org/mailman/listinfo/qgis-user
>
>
>
>
>     -- 
>     tolennon at gmail.com <mailto:tolennon at gmail.com>
>
>
>
>
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