2

I want to create a flow map in QGIS.

I have a list of cities and I have to show how many people travel from one city to another. For example, 5 people traveled from Vantaa to Helsinki, 10 people traveled from Tampere to Helsinki, 50 people traveled from Joensuu to Helsinki etc,. The flow strength (number of people) should be shown with different thickness lines, where 5 is the thinnest and 50 is the fattest.

underdark
  • 84,148
  • 21
  • 231
  • 413
Ann
  • 21
  • 2
  • 1
    It isn't clear whether you want to visualize exact ROUTES that were used or just a general migration flows from one city to another. – SS_Rebelious May 03 '13 at 19:50
  • i would like to show general migration flows – Ann May 04 '13 at 07:46
  • What spatial data are you currently working with? Do you have each city as a point? Or just your movement data in table format? The simplest solution would involve creating line features between point features representing cities (using plug-ins such as https://plugins.qgis.org/plugins/PointConnector/ amongst others), with number of people attributed to the relevant line feature. With this in place you can categorically symbolise your data with line thickness dependent on your 'number of people' attribute. – RobinHorner Aug 29 '18 at 05:09

2 Answers2

2

I haven't used it myself so far, but i think that the Flow Mapper Plugin would be the way to go.

If you can't find the plugin, try checking "show all plugins, even those marked as experimental" under the Plugins -> Fetch python plugins -> Tab:Options

To get additional info on the plugin, browse to your .qgis folder within your users folder.

.qgis/python/plugins/FlowMapper

There you will find a folder containing a documentation (also available here) and another folder with example data.

The developer rates his plugin as experimental at the moment, but fully functional.

Good luck

Bernd V.
  • 3,179
  • 25
  • 49
  • FlowMapper is available through the official repo, no need to add a different repo. – underdark May 04 '13 at 11:18
  • strange... couldn't find it, using master on Linux. Ok, will adopt my answer. – Bernd V. May 04 '13 at 11:40
  • Thanks for your suggestion, but flow mapper didnt solve my problem or if i be honest it didnt work or i just couldn`t know how to use it properly. I went the easy way and solved my problem by adding a new shapefile layer (line), and then i just connected manually one city to another and typed the values what i needed and added them to the map. – Ann May 06 '13 at 20:54
2

I am the developer of qgis flowmapper plugin. I would be please to answer any questions regarding the plugin.

A readme and tutorial data is already included within the zip file that you have downloaded either from the plugin repo or from the website www.cempro.tk

Briefly, supply (i) input node coordinates as text file and (ii) flow data matrix as text file in white space deliminated format and plugin generates node2node straight flow lines automatically in shapefile format.

Example: You have 3 nodes, cities a, b and c
(i) Input node coordinates (geographic) text file should appear as;
30.123 42.345
29.345 41.456
29.679 40.789

(ii) Flow matrix (from city to city) text file should appear as;
0 100 200
150 0 350
70 140 0

Flow mapper is tested to be working in Windows only. It would probably cause error in MacOS or Linux due to slashes in the file paths. But if you are on Windows, you will not face any problems.

cempro
  • 644
  • 5
  • 11