Dollar sign before a variable

To access a column, use:

my_data[ , cond]

or

my_data[[cond]]

The ith row can be accessed with:

my_data[i, ]

Combine both to obtain the desired value:

my_data[i, cond]

or

my_data[[cond]][i]

I guess you need get().

For example,
get(x,list), where list is the list and x is the variable(can be a string), which equals list$x.

But in get(x,list), x can be a variable while using $, x cannot be a variable.

$ works on columns, not individual column objects. It's a form of vectorization. The code

corrections$BookDate = as.Date(corrections$BookDate, format = "%m/%d/%Y")

converts the contents of the BookDate column of the corrections table from strings to Date objects. It performs it in one operation, assignment.

Do the following and it will fix your problem:

new_data <- rbind(new_data, c(cond, my_data$cond))