Quite often we develop taxonomies that have many sub types for each Content Type. This can get awkward when the Library has many Content Types causing the view to get very wide. One option is to create a calculated column that combines the site columns into a single column. Please note that to get this to work properly you should make the default on a choice column blank. Otherwise, it will show the default choice for each site column.
Lets start creating our new calculated column! Click on the cog in the upper right of the screen.
Then select Site Settings (you will need at least design permissions to create a new site column).
Then click on Site Columns under the Web Designer Galleries section.
After that, click on Create in the upper left of the screen.
Select the Calculated (calculation based on other columns) radio button.
Name your new site column Calculated Column
For this exercise we will be combining Column 1 and Column 2.
Click on the formula area and enter =. On the right select Column 1 and click on add to formula. Then enter & and select Column 2 and click on add to formula.
The Formula should look like this :
=Column 1&Column 2
Next add you new Calculated Column to your view and you are good to go!