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I am trying to sort point symbols at the same coordinates in a line. The first picture shows how I want it to be (all symbols in a single horizontal line), the second how it looks with the standard grid-based point displacement (multiple, unwanted rows of symbols, and therefor also an unwanted overlap of text and symbols).

Is there any way/plugin to either change the parameters of how the grid is built (number of rows/lines) or any other way to show symbols in a line?

I am not hugely into scripting or programming though.

enter image description here

enter image description here

PolyGeo
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Tyak
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  • Welcome to GIS.SE, Tyak! Please keep in mind, that from a cartographical point of view this display of information is not desirable, since the exact location of the ruins can not be determined. – Erik Nov 23 '18 at 08:36
  • I agree that this is not an exact map, but since most of the stuff I am showing is only known from literature anyways I don't think that it'd matter much.

    Also: You gotta do what the boss wants you to do, so...^^

     – Tyak Nov 23 '18 at 09:05
  • Sometimes telling your boss, that their ideas are bollocks, is the better solution ;-) could you tell some more about your data? Are the ruins all in one shape file? Are they separate points for each location, or do you have one point per city/site and then attributes? – Erik Nov 23 '18 at 09:19
  • they are all different points with the same coordinates on the same shape file. – Tyak Nov 23 '18 at 09:33
  • I could put them into single points with attributes too if that woud help... – Tyak Nov 23 '18 at 10:54

2 Answers2

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I would calculate offset distance (dx) for each feature, so that I can position them by (x, y) = ($x+dx, $y).

enter image description here

An example of expression to calculate dx is:

with_variable('my_array', array_agg("symbols", group_by:="geom_to_wkt($geometry)"), 
               5 *(array_find(@my_array, "symbols") - floor(array_length(@my_array)/2)))
  • You will need to modify "symbols" according to your attribute field which defines your categorized symbols.
  • The second line has a factor 5, but it is arbitrary. Please adjust this number by visually checking your output.

[EDIT]

To modify x-location of symbols according to the dx calculated above, there would be some options:

(Option 1) Geometry generator

This is dynamic way, and probably a preferred option. In the Layer Properties window, click on Change button next to Symbol. Then select Geometry generator as the Symbol layer type and Point/Multipoint as the Geometry type. The actual expression would be make_point($x+"dx", $y).

enter image description here

(Option 2) Create points layer from table

This tool is found under Processing Toolbox | Vector creation. It is more static way and requires new_x field (by $x+"dx") and new_y field ($y, so it is not new). One merit of this approach is that you can later modify new_x and new_y field manually, so that you can place them in two or three rows if you like.

enter image description here

Kazuhito
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  • But wouldn't that give every symbol a fixed position? Wouldn't that result in gaps between symbols if some weren't there at a location? – Tyak Nov 23 '18 at 12:14
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    @Tyak the array_length part counts the number of your symbols and array_find checks its position in the array. If you have many symbols the array is extended. – Kazuhito Nov 23 '18 at 12:17
  • I am a bit embarrassed to admit, but it seems I'm too stupid to get the formula for the position in your very first paragraph ((x, y) = ($x+dx, $y)) working. When I copy it into the symbol style offset formula edit thingy I get an invalid expression message... – Tyak Nov 26 '18 at 08:21
  • Thanks @Tyak I think some of functions take arguments differently when directly used in Layer Properties. As a test, please change group_by:="geom_to_wkt($geometry)" to group_by:=geom_to_wkt($geometry) ( remove double quotation marks ) and see if it works. – Kazuhito Nov 26 '18 at 10:24
  • oh no, you might have misunderstood me (or I wasn't clear enough about my problem). I can't figure out how to insert any kind of formula into the feature positions. the "dx"-generation worked fine. but I can't find where/how to put the offset into the points! (and also thank you very much for your patience ; )) – Tyak Nov 26 '18 at 14:04
  • Ah, sorry @Tyak I've forgotten that part. Edited my answer to add some possible options. There are merits and demerits in each approach. Hope any of them works for your case. – Kazuhito Nov 26 '18 at 14:54
  • Thank you so very much, @Kazuhito! I got the solution you provided working as intended, though I wasn't entirely satisfied with the offset being a true distance and therefor being scale dependand.

    With the help of a colleague I was able to put the offset value (dx) into the offset calculator for each point with the formula concat( to_string( "dx"), ',', to_string(0) ) Thanks again for your help!

     – Tyak Nov 27 '18 at 12:34
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Add extra points at each location to expand the grid layout until the original point symbols fit on a single line of the grid.

Make the extra points invisible by setting the opacity of their symbol to 0%.

In this example I had 5 points at one location. I added another 16 points to expand the grid to 5x5, forcing the main 5 points onto the same line. I left the grid lines on so you can see the layout.

enter image description here

Note: Leave the attributes of the duplicate points blank, so you don't later get confused and think they represent real-world features. It's probably best to make a backup of the point file.

csk
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  • This seems to be a very easy and quick workaround, although it could become a bit confusing with the exponentially growing number of blank points. Thank you anyways. I will keep this trick in mind! – Tyak Nov 27 '18 at 12:36