QGIS Operations

Select features: Edit>Select>Select Features by [Value, Expression, etc.]

To change color of selection and background: QGIS>Preferences>Canvas & Legends – Applies to new projects.

To create a new layer from a selection: Right click on the layer with the selected features. Choose: Export>Save Selected Features As... OR Select the features and then use Edit>Copy and then Paste Features As>New Vector Layer (or a Scratch layer).

Transfer Strava data to QGIS – Navigate to one of your Activity pages and from the more (ellipses) menu, select “Export GPX“. In QGIS use Layer>Add Layer>Add GPX Layer…

Printing a Google My Map

After composing the map, you can either click on the 3 dots to the right of the map title and select “Print map” or select “Preview” and then if desired you can hide the legend by clicking on the 3 dots next to the map title and select “Collapse map legend” and then “Print map”. Using 11 x 17 was the best page size for the priority route map.

Working with images in GIMP

I rarely use GIMP and whenever I do I need to re-learn basic functions. I recently wanted to place two images side by side. I opened one image. To make space for an adjoining image, I used Image>Canvas Size to increase the canvas width. To add a second image I used File>Open as Layers. I could then scale the second image to match the first using Layer>Scale Layer. To open the tools menu, use Windows>New Toolbox. To open the Layers menu, use Windows>Dockable Dialogs>Layers. Right click on a layer to add and Alpha Channel. Once the two images are combined, use File>Save As.

Change a photo’s date and time

  1. In the Photos app  on your Mac, select the photos you want to change. Command-click to select more than one photo.
  2. Choose Image > Adjust Date and Time.Tip: You can also double-click the date that appears in the Info window to change the date. To show a photo’s Info window, double-click the photo, then click the Info button  in the toolbar. 
  3. Enter the date and time you want in the Adjusted field.
  4. Click a time zone on the map and choose the closest city, if necessary.
  5. Click Adjust.

Limit number of email msgs downloaded from Gmail

I don’t delete most email and have many, many messages in my Gmail inbox. I mostly use Mac Mail to read and send email, so whenever opening the mail program, all of the Gmail messages are downloaded, which takes forever. To limit the number of messages downloaded, but kept on the Gmail server, use the following:

Gmail>Settings (gear symbol)>See All Settings>Forwarding and POP/IMAP. Scroll down to Folder Size Limits and set the number of messages to be downloaded. It is currently set to 5,000.

Turning on Bluetooth w/out a mouse

I accidentally turned off Bluetooth and my mouse stopped working on my Mac. To turn Bluetooth back on with just the keyboard, use Command-Spacebar to bring up Spotlight search. Type Bluetooth File Exchange which will prompt you for turning on Bluetooth by hitting the Return key.

How to find locked files on a Mac

I have a video headlight for my bike and occasionally I want to lock a file to make sure it’s not written over with subsequent videos. Later I want to unlock them. One way is to reformat the memory card. Another way is to do it on theMac. However, Finder does not indicate which files are locked. This unix command can be used:

Start the Terminal

cd to the proper folder. I moved to the top level, then to Volumes, then to the volume with the memory card which is inserted into the MacBook Thunderbolt port.

“sudo find . -flags uchg” [without the quotes. This will list locked files. To unlock files, use: “sudo chflags -R nouchg”]

Summarizing Numbers data

I have a table with a row for each bike facility occurrence in each VA county and the trails in each county. I want to summarize that data. It can be done using Categories in Numbers. Under Organize, select Add Categories. This will sort the table and create a new row for each category. Cells in that row can be designated to Sum the values in that column. The Category was Locality and the Length of each facility segment is totaled by clicking the gears in the category row for that attribute. All Categories can be collapsed and the total for Length calculated by selecting the category totals and pasting them into another sheet and totaling those.