Month: February 2016

Highlighting Selections in QGIS

I have been working a lot with points recently, and one thing with the default selection highlighting in QGIS is that selections do not really stand out. This is especially true with point layers.

A bit of an extreme example, but there are 15 points selected in the middle of this image.

hard_to_see

However, we can remedy this with the Expression Plus plugin (by Nathan Woodrow) and a rule based symbology.

plugin

This plugin adds a great function: isselected()

With this we can easily create rule to symbolise features that are selected.

The rule for symbology is as follows:

QGIS 2.12+:

isselected( @layer_name )

QGIS 2.8:

isselected( 'ACTUAL_NAME_OF_LAYER' )

So we can see that 2.12 has added a slightly more dynamic way of applying the symbology.

symbology

We can now slightly more easily see our selection.

more_visible

But one final setting. With symbol levels we can really make the selections pop.

symbol_levels

Symbol levels can be set from the bottom right of the styles tab, through rendering order. We simply want out selection to have a higher number than the other symbologies. Thus being rendered in a later pass and appearing on top.

final_selection

Much better.

Mapping Google Location Data

A cool python script has been created that allows you to easily convert your google location (Takeout) data into a shapefile.

You can get your data from: Google Takeout
And you only need the “Location History – JSON format”

The conversion python script can be downloaded from: GitHub

The python script requires GDAL and its python bindings, but can be easily run if you installed QGIS using the OSGeo4W installer. From the advanced installer, under the Lib section.

instruct

Then using the OSGeo4W Shell.
shell

Run the command:

python "C:\FullPath_to_Python_Script\read_location_data.py" "C:\FullPath_to_Input_File\LocationHistory.json" "C:\output_path" output_file_name ESRI_Shapefile

Example:

python "C:\FilePath\Takeout\Location History\read_location_data.py" "C:\FilePath\Takeout\Location History\LocationHistory.json" "C:\FilePath\Takeout\Location History" output ESRI_Shapefile

Then just style it in QGIS as desired.
GoogleTakeOut