I have a problem where my buffer lines do not dissolve with the rest of the data. I want the buffer lines to "open" where they cross other data, right now it looks like the buffer data is layered on top of the other data.
In the picture I have pointed out a place where I would like the buffer to "merge" with the rest. There are plenty of those places, I have tried the dissolve but this is the only result I have gotten. Picture of the problem.
What you want to do is dissolve but you will need to dissolve the polygons based on a field from the attribute table. If all of the shapes that you want to merge have the same value in that field of the attribute table you'll be able to utilize dissolve.
Please see this post from gis.stackexchange:
Merge intersecting polygons into one which are part of the same feature
Related
I'm looking to create a packed bubble graph like the below (size of the bubble corresponds to population, and the color of the bubble corresponds to number of widgets sales). The graph is exactly the way I need it, except that I would like to arrange the countries so that they are grouped by continent. Is there a way to do this in Tableau?
I've tried to recreate a similar scenario even though it's not clear if the bubble color should (or not) be related to a specific field.
That being said, using the superstore dataset, I've "grouped" customers by region (color) so they are some how aligned through inner circles.
In order to do so, I just sorted the region pillow in the detail section.
See below.
I have merged four different layers into one new one in QGIS, but I want this layer to have different information then the old layers. I want all the buffered 'islands' to have a different ID and a calculated area. However, now in the attribute table I just see four features, one for each layer that I merged. Is there a way to update the attribute table to consist of new features (one for each 'island')?
This is what the layer looks like:
And this is what the attribute table now looks like:
And this is what I want (the 5th and 6th column especially):
You must create a feature for each monopart geometry, you can achieve this using the 25.1.18.46. Multipart to singleparts tool, and then use the field calculator to get the area, you can find here how to calculate area Calculating polygon areas in shapefile using QGIS.
I have 16,000 rows of data in excel.
In this excel, I have census block numbers.
What I want to achieve is that I want to make a map layer for these block numbers.
Then, if I click a polygon, the information of a block number display on the popups, like which state, county, and so on.
How can I do that? Do I have to use geojson files for this?
Because, many exmaples in the mapbox use geojson.
But I don't have any coordinates for these block numbers and 16,000 rows are really big to me. I got only block numbers.
But I got shapefiles for whole state block numbers.It is too big to upload mapbox gl js.
If geojson file is the way to achieve my goal, can someone tell me the orders that I can follow?
Or is there other way, please advise me.
Thanks.
So you have a geometry file ("shapefiles for whole state block numbers") and a data file ("16,000 rows of data in excel"). You want the user to click on a boundary in the geometry, and see data from the data file. You have two main options:
Join the data and geometry first (eg, use geojson-join, then upload to Mapbox as a tileset.
Upload just the geometry. Load the CSV file when the web page loads, then when the user clicks, display something from the CSV file.
I have been rendering a FeatureCollection of polygons into the Map (in one GeoJSONLayer). The size of each polygon is big (5mb, 10mb). With user interactions, the colours of polygons would be re-calculated & changed constantly. We are using data-driven method and keeping the data in properties of each feature. So GeoJSONLayer has to call .setData(geojson) everytime the data and colours changed (they are kept in properties).
I find above approach is lead to performance issue since the size of geojsons is big and calling .setData() is expensive.
I'm thinking of separating the geojson source and the data, style, colouring and calling direct function (setPaintProperty) whenever colours changed would be better than.
Someone told me that .setData and .setPaintProperty would do the same thing, both 2 will trigger re-rendering whole polygons.
Kindly need help to advice on this matter
Thanks a lot!
If I understand you correctly, you're asking which of these two is faster:
map.setData(mylayer, mygeojson)
map.setPaintProperty(mylayer, 'fill-color', ...mydatadrivenproperty)
I haven't tested, but I'd assume the second is faster, because the first one has to:
Parse the GeoJSON
Convert it to vector tiles
Repaint
whereas the second just has to parse the property repaint. Try them both out to see.
You may also consider a third way, which is to have a second layer which is a highlight, which you update by calling map.setFilter(mylayer, ...).
I have a group of polygons which I merged to create one large polygon using the editor toolbar. This worked fine but there are still 5 or 6 lines contained within the large polygon. I'm assuming these are contained within the polygon because when I select the polygon the lines are selected too - how can I get rid of these 'rogue' lines, if I merged the polygons how come I have lines now? Any help appreciated!
My guess is that your polygons don't have correct topology, I mean the sharing border is not exactly the same. There is very likely a tiny gap and when you merge your polygons, you see those tiny gaps as line (try zoom to very detail). If this was problem, solution is obvious - you should correct topology of your polygon before merge - you can use topology class with no gaps rule.
You can manually remove the lines by:
1) Enter an edit session
2) Selecting the feature
3) Select the "Edit Vertices" tool from the editor toolbar
4) Find the vertices of the rogue lines, select them, and delete them
5) End edit session and save edits
ESRI resource:
http://resources.arcgis.com/en/help/main/10.1/index.html#//01m80000003p000000