Update 2007-05-23 21:29: Making my images a bit smaller to make the post fit…
A common problem that arises with new (and sometimes more experienced) users of EverNote is that they don’t realize how powerful the Category Intersection panel is. By default this panel is not activated when you first start EverNote, and you may never realize what you’re missing.
Let’s say you have a database of notes, organized with categories. Let’s say that you’re using a whiz-bang application like EverNote, that actually lets you have multiple categories per note.
I don’t want to get all math-y on you, but it’s possible to these categories and note with something called a Venn diagram. That’s basically a way of drawing how sets (in our case, categories), relate to each other.
For illustration purposes, I’m going to talk about two categories: “Things to Read” and “Already Read”. I’ve got some notes, some of which are in one category or the other, or in both. Here’s a Venn diagram showing my example.
As you can see, I have a large category called “Things to Read”. It’s got a total of three notes in it (represented by little black stars.) I’ve got a smaller category called “Already Read”, containing one note. The full yellow circle is “Things to Read”. The full blue circle is “Already Read”. The overlapped area between the two circles (shaded green) holds any notes that are in both of the categories. You’ll notice that the one note in “Already Read” is also in “Things to Read”.
Okay, fine for a math lesson. But what does this buy us? I’ve put this diagram in just to help you understand what kind of powerful searches you can achieve with EverNote. In plain terms, you can search (or filter) for the following things:
- all notes that are in one specific category, e.g., either the yellow or blue circles
- all notes that are in either one category, or another (or another or another, etc.), e.g., in both circles together
- all notes that are in two (or three or four, etc.) specific categories, e.g., in the green overlap between the two circles
- all notes that are in a category, but not in another category, e.g., in the yellow circle, not including the green area
Single Category
This is the easiest way of narrowing down your notes. By simply clicking on a category in the left-hand category panel, you are filtering for all notes that are in that category. This one is so easy that you’re most likely doing it without even thinking about it.
You can see an how I’ve done this in the diagram below. Note that this example corresponds to finding all of the starts in the full yellow circle in the Venn diagram above.
Multiple Categories (Note Can be in Any)
In logic, there is something called the OR operator (or disjunction). It is referred to as union when dealing with sets. All that that means is that if I say that something is in Category A or Category B, then the note is in either A or B, or both. (There is something more special called the “exclusive or”, which means A or B, but not both, but we’re not going into that.)
Again, this kind of filtering can also be done from the regular Category panel, and you’re most likely using it without thinking about it. When you Ctrl + Click on more than one category in the panel (thereby highlighting two or more categories), you are performing an OR operation. The tape then holds any notes that are in ANY of the categories that you have selected.
The diagram below shows you how I’ve selected both categories in the category panel. All three notes are being shown. Note that the one note in “Already Read” is in “Things to Read” also.
Intersection of Categories
The third kind of filtering is fancier, and is done using the Category Intersection panel. (You can turn on the panel in the options.) Just like there is an OR operator, there is also an AND operator (or conjunction). It is referred to as intersection when dealing with sets. All it means is that if I say that something is in Category A and Category B, then the note is in both A and B.
If you’ve been using the Category Intersection panel, you’ve been using this kind of filtering. When you click on a category, and then click on another category in the intersection panel, you filter with the AND operator. The tape will hold all notes that are in ALL of the categories that you’re clicking on in the intersection panel.
For example, here’s a snippet of my category intersection panel. I originally clicked on “My Computers”, which contains seven notes. Using the intersection panel, I then clicked on “Tips & Tricks”, followed by “Hardware”, followed by “Images”. This gives me all (two) of my notes that are in all four of these categories.
Going back to our running example, the diagram below shows you the intersection of both the “Things to Read” and “Already Read” categories. You can see that exactly one note is in both categories.
Negation
The trickiest filtering that you can do with the Category Intersection panel involves another operator called the NOT operator (or negation). It is called the complement when dealing with sets. All this means is that when I say that something is in Category A but not in B, then the note is in A, but most definitely not found in B.
The ability of EverNote to handle negation in the intersection panel seems to be a well-hidden secret, if not a downright undocumented feature. I’ve looked through the most recent version’s help, and didn’t find anything. I was searching for information on “category intersection”, “negation” and “not”. No joy.
To invoke the negation is very simple; it just requires a Ctrl+Click when you’re in the intersection panel. For instance, let’s go back to our example listed above. We want to find all notes that are in “Things to Read” but not in “Already Read”. Select “Things to Read” in the Category panel. Then, in the Intersection panel, Ctrl+Click on “Already Read”.
You’ll see a little red tilde (~) beside the “Already Read” category. This means that it has been negated - no notes that are in that category are being shown in the panel. This holds true even if the note belongs in another category also.
For this example, I had a total of three notes in the “Things to Read” category, and one note in the “Already Read” category. This last note was also in the first category. By using the negation in the category intersection panel, I was able to winnow out anything that was already read and just give me those things that I still need to look at.
Summary
I’ve combined some terminology from logic, set theory and common English to try and explain the different ways that you can filter your notes in EverNote. Here’s a little summary table to make it easier for you:
| English | Logic | Set Theory | How to Achieve in EN |
| All notes in Cat A or Cat B | OR
disjunction |
union | Ctrl+click on multiple categories in the Category panel (top left). In the example above, this will give you both the yellow and blue circles, including the green overlap. |
| All notes in both Cat A and Cat B | AND
conjunction |
intersection | Click on one category in Category panel (top left), then click on second category in Intersection panel (bottom left). In the example above, this will give you the green overlap between the two circles. |
| All notes in Cat A, but not in Cat B. | NOT
negation |
complement | Click on Cat A in the Category panel (top left), then Ctrl+click on Cat B in the Intersection panel (bottom left). In the example above, this will give you the yellow circle, less anything in the green area. Note that the order of clicking does matter, e.g., going in reverse order will give you all notes in Cat B, but not in Cat A. |
Any questions?
