search for: 72145a

Hello everyone, I would appreciate any help with the following. My dataset is a list containing matrices. So if you type e.g. data[[1]] you get something like: [,1] [,2] 361a A T 456b A G 72145a T G ........ As you can see my rows have names which are character strings containing numbers and letters. I want something similar to a histogram, per column. i.e. I want to know how many times I have a single repeat character in a column and how many times I have a twice repeated character...