From 2c73f67d3a3f6b0a7dcd317f57f69e616ff14069 Mon Sep 17 00:00:00 2001 From: Michele Tobias Date: Thu, 24 Mar 2022 13:18:47 -0700 Subject: [PATCH] Update README.md --- README.md | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) diff --git a/README.md b/README.md index 8f1a3a3..26af79a 100644 --- a/README.md +++ b/README.md @@ -221,7 +221,7 @@ Selecting streets by hand is helpful, but depending on what we want to do, we mi 1. We'll build an expression in the white box on the left side of the tool. In the center panel, expand the *Fields and Values* list. 1. Double click the *classcode* field to add it to the expression box on the left. 1. Then click the *=* button to add an equal sign to the equation. -1. We can also click the *All Unique* button on the right to see all of the values that are found in the *classcode* column. I don't recommend using this option on continuous data; it's best for categorical data with a relatively small number of unique values. Click *'1'* in the list. Note that while we think of the items in this list as numbers, this column was likely defined as text, so this is why the numbers are wrapped in quotes. If we tried to use the number without the quotes, the GIS would find no matches because it would be looking for the number 1, not the text 1. Your expression should look like *"classcode" = '1'*. If QGIS read the *classcode* field as numbers, your expression should look like this: *"classcode" = 1* +1. We can also click the *All Unique* button on the right to see all of the values that are found in the *classcode* column. I don't recommend using this option on continuous data; it's best for categorical data with a relatively small number of unique values. Click *'1'* in the list. Note that while we think of the items in this list as numbers, this column was likely defined as text, so this is why the numbers are wrapped in quotes. If we tried to use the number without the quotes, the GIS would find no matches because it would be looking for the number 1, not the text 1. Your expression should look like *"classcode" = '1'*. If QGIS read the *classcode* field as numbers, your expression should look like this: *"classcode" = 1* **NOTE: in QGIS 3.24, both options work.** 1. Click *Select features*. You'll notice that rows in the attribute table and lines on the map have been highlighted. What do you think a *classcode* of 1 means? **Challenge:** Try changing the expression to select different *classcode* categories. What do you think each category means?