QGIS expressions, variables, data defined settings: putting it all together! 

Fantastic Nyall. I use expressions all the time in so many different places. Coming across this yesterday, you have opened up even more expression opportunities for me. Awesome, thanks!

INDEX 00:00:00 | intro 00:03:06 | field calc 00:18:25 | variables 00:27:50 | expressions / variables / context 00:28:47 | variables tab 00:32:50 | global variable / project 00:37:33 | variable layout 00:39:10 | overwriting defined by data

Your masterclass helped me to discover something that I have been wanting to do in QGIS, but thought I could not and that is to set a reference scale at the layer level. If I want to have a label that scales with the map, and currently it's a 10pt font at a map scale of 100,000, then I just set the font to be equal to 10 * 100000 / @map_scale. And if I want the label to scale but never be smaller than 6 or greater than 12 it would look like this: max(min(10 * 1000000 / @map_scale,12),6) Awesome! Thanks Nyall!

This was awesome!! Thank you so much for doing it.

Thanks for the helpful video! It is always cool to see other GIS professionals tips and tricks. I have a colleague that is going to be switching to QGIS...hopefully soon, I will definitely be recommending this video to him!

Great tutorial! THX.

THANK YOU! I've been searching how to display data differently for different map views. I have some contours that I want yellow when it's on top of my ortho (which is green from trees) to make it stand out, but grey when the ortho layer isn't visible (which would be on top of white, where yellow doesn't show well). I wasn't finding much so thought I'd learn more about expressions since that's what I assumed would be used. Then, at the end of your video, you showed exactly what I've been trying to do for weeks. Being new and no mapping experience beyond using maps, it was hard to know the correct terminology to search for. You're also a very good teacher. Again, thank you!

Great information.

Great presentation Nyall. I think this the third time I've watched this video and I get something more out of it each time. Looking forward to the next one!

Pure GOLD, much appreciated

Brilliant! It was neat learning that /n and || have shortcuts in the expression window, that the variables symbol colour and value exist, as does the button 'modify all selected attributes simultaneously’. Great cartographic tip placing coastal settlement labels out to sea; I didn't know that was a recommended standard. More importantly, that setting project level variables (with for example SQL true false statements) can vastly improve workflows, as can understanding data defined override hierarchy (global < project < layout); exactly what the doctor ordered! Cheers again Nyall.

Very grateful for this video. Thank you.

Great video Nyall, really learned a lot. I will pass the video link on to my geoscience user group.

Thank you for these tips! I really hate changing a lot of things when my boss suggests something when I'm nearly done with more than 20 layouts.

Thank Nyall, clear explanation

Wow! Wonderful! Thank you so much!

Very good, i always wanted to learn more about expressions, thak you!

Thank you Nyall !

Thanks Nyall this is very helpful.

thanks a lot! amazing tutorial!!!!

Great Video!

Great tutorial! I am sure it will be the go to expressions reference for a good while. A quick question though. Is there a way to use a project variable in the layer query builder as a parameter?

Thank u

Thank you Nyall, This is an area I have never properly explored and makes so much sense to "productionise" your maps. Do you have a qgz template file with a number of these variables assigned so you have a consistent approach to naming?

exellent

how can I use fields from other layers? eg. I have a layer name "schools" with a field "middle school", how can I use it when I am in atlas? sorry my english bad.

how to adjusted paper size in qgis 3.14

Thanks so much!! Just one quick question: I think you are using elementary os isn't it? Before erasing everything on my current machine I wanted to ask if it's more or less easy to install qgis 3.14 on that distribution?

Expression is greater thing no more layers

This is great. Thanks so much, Nyall!