Use input text file to select rows in data table

I have an app that displays a data table, in this data table the user can select rows by clicking on them to display in various figures. i want to include a function where the user can input a txt file as a single column list of row names. i then want to convert this txt file to a single column data frame and use the match() function to find the rows in the data table that match the text list. i then want to select the rows that match to display in the figures. i am using the fileInput() option to read in the txt file and i have attempted to manipulate the txt file in the reactive({}) function but that has not worked. any help would be greatly appreciated.

Can you you please post a minimal reproducible example, or reprex? This should include a sample data set and the code that you have already tried. It is pretty hard to decipher what could be causing you issues without seeing the actual code you are using. You are much more likely to get the help you need if you do this.