# Filters

It is possible to specify filters to filter the data that will be printed. There are two types of filters: the row filters, which are specified by the keyword filters_row, and the column filters, which are specified by the keyword filters_col.

The filters are a tuple of functions that must have the following signature:

f(data,i)::Bool

in which data is a pointer to the matrix that is being printed and i is the i-th row in the case of the row filters or the i-th column in the case of column filters. If this function returns true for i, then the i-th row (in case of filters_row) or the i-th column (in case of filters_col) will be printed. Otherwise, it will be omitted.

A set of filters can be passed inside of a tuple. Notice that, in this case, all filters for a specific row or column must be return true so that it can be printed, i.e the set of filters has an AND logic.

If the keyword is set to nothing, which is the default, then no filtering will be applied to the row and/or column.

Note

The filters do not change the row and column numbering for the others modifiers such as column width specification, formatters, and highlighters. Thus, for example, if only the 4-th row is printed, then it will also be referenced inside the formatters and highlighters as 4 instead of 1.

## Example

Given a matrix data, let's suppose that is desired to print:

• only the 5-th and 6-th column; and
• only the rows in which the 5-th and 6-th columns are positive.

Then we can use one of the following approaches:

f_c(data,i)  = i in (5,6)
f_r1(data,i) = data[i,5] >= 0
f_r2(data,i) = data[i,6] >= 0

and set filters_col = (f_c,) and filters_row = (f_r1,f_r2), or

f_c(data,i) = i in (5,6)
f_r(data,i) = (data[i,5] >= 0) && (data[i,6] >= 0)

and set filters_col = (f_c,) and filters_row = (f_r,).

Note

The keywords related to the filters are supported in all back-ends.