![population layer input data in watergems population layer input data in watergems](https://underdark.files.wordpress.com/2019/04/flows_from_nodes_and_edges_basic-1.png)
This SQL query joins the geographic information from the nodes table to the flow weights in the edges table based on the node IDs. More specifically, this is a job for Virtual Layers: Layer | Add Layer | Add/Edit Virtual Layer To achieve our goal, we need to join both layers.
![population layer input data in watergems population layer input data in watergems](https://communities.bentley.com/cfs-file/__key/communityserver-discussions-components-files/5925/lb7.png)
The first step therefore is to create the flow line features from the nodes and edges layers. There’s usually a point layer (here: “nodes”) that provides geographic information and a non-spatial layer (here: “edges”) that contains the information about the strength or weight of a flow between two specific nodes: Survey data like the one described above is a common input for flow maps. The next step was the geographic visualization of the flow data and this is where QGIS comes into play.
Population layer input data in watergems software#
In order to evaluate the potential for such a system – which would not only imply a material change of the cups in terms of hardware but also introduce some software solution with the convenience of getting back the necessary deposit that I pay as a customer and some software-solution in the back-end that handles all the cleaning, distribution to the different coffee-shops and managing a balanced stocking in the stations – I conducted a survey So I have been looking for a system that gets rid of the disadvantages or rather provides the advantages of both approaches and I came up with the following idea: Installing a system that provides a re-usable cup that I only have with me when I need it. With the re-usable cup I carry it all day even though most of the time it is empty and it is clumsy and consumes the limited space in bag. Neither system seem to satisfy me as customer: the paper-cup produces a lot of waste, though it is convenient because I carry it only when I need it.
![population layer input data in watergems population layer input data in watergems](https://i1.rgstatic.net/publication/331478148_Demand_Allocation_Pattern_for_Consumption_Points_in_Water_Distribution_Networks/links/5d2d6fc1299bf1547cb9dfa3/largepreview.png)
So I ended up buying one of these mostly ugly and space-consuming reusable cups. But what has bugged me for a long time is the fact the coffee or hot beverages in general are almost always served in a non-reusable, “one-use-only-and-then-throw-away” cup. Here’s how he tells the story behind the data:Īs a nearly daily commuter I like to enjoy a hot coffee on my train rides. Why was this data collected?īesides travel demand, Hans-Jörg’s survey also asks participants about their coffee consumption during train rides. In addition, the locations were stored in a second text file containing id, location name, and co-ordinates. Finally, these connections (edges that contain start id, destination id and number of nominations) were stored in a text file. Afterwards, the flow information was aggregated to count t he number of nominations of each connection between different places. This cleaning and the following geocoding step were implemented in Python. The answers had to be cleaned up to correct for different spellings, spelling errors, and multiple locations in one field. The data presented in this post stems from a survey conducted among public transport users, especially commuters (available online at: ). Among other questions, the questionnair asks where the commuters start their journey and where they are heading. It’s the result of a collaboration with Hans-Jörg Stark from Switzerland who collected the data.
Population layer input data in watergems how to#
This tutorial brings together many different elements to show you exactly how to create a flow map from scratch. If you’ve been following my posts, you’ll no doubt have seen quite a few flow maps on this blog.