data.table | R 's data.table package extends data.frame

Here, we can use if/else as ifelse requires all arguments to be same length all(a == 0) is of length 1, along with the 'yes' but 'no' is not of length 1, which leads to recycling

We don't need as.name. Object on the lhs of = is not evaluated correctly. Instead, we could use a named vector in on with setNames

I named your first data.table dt_A, the second one dt_B and assume, you identify the entries in dt_B by id, year and class.

I got an error with that last step, but if you have a more recent version of data.table that behaves differently hten by all means just :

I came across the same problem on a few occasions, which led me to avoid mixing dplyr with data.table syntax, as I didn't take the time to find out the reason. So thanks for providing a MRE.

Looks like dplyr::arrange is interfering with data.table auto-indexing :

• index will be used when subsetting dataset with == or %in% on a single variable
• by default if index for a variable is not present on filtering, it is automatically created and used
• indexes are lost if you change the order of data
• you can check if you are using index with options(datatable.verbose=TRUE)

If we explicitely set auto-indexing :

The problem seems to be in this line

You are not preventing the form from being submitted in your function. You do write return false; but that won't work here as that needs to be done in a fashion like below where somefunction will return false:

Here is one way with tidyverse

1. Loop across the columns found in the unique values from 'var' column of 'tbl'
2. Get the column name of looped column with cur_column() to create a logical expression on the 'var' column of 'tbl' ('i1')
3. Use match to get the position index where the column values match with subset of 'cod' column of 'tbl'
4. Extract the corresponding 'txt' column of 'tbl' from the subset based on 'i1'