Table Format and Style

Each back end configures its output with two objects: a table format, which states how the table is printed (for example, which lines are drawn), and a table style, which states how the table is decorated (for example, the face of the column labels). Both objects have backend-specific types (TextTableFormat, LatexTableStyle, and so on), which also carry backend-specific options. Hence, switching back ends would require rewriting those configurations.

To avoid this, the keywords table_format and style of pretty_table also accept the backend-agnostic objects TableFormat and TableStyle, which describe the table lines and decorations once for every back end:

table_format = TableFormat(;
    horizontal_lines_at_data_rows = :all,
    vertical_lines_at_data_columns = :none,
    header_line = LineStyle(; style = :dashed),
)

style = TableStyle(;
    title = Face(; weight = :bold, foreground = :magenta),
    first_line_column_label = Face(; slant = :italic, foreground = :blue),
)

pretty_table(matrix; table_format = table_format, style = style)
pretty_table(matrix; backend = :latex, table_format = table_format, style = style)
pretty_table(matrix; backend = :typst, table_format = table_format, style = style)
pretty_table(matrix; backend = :excel, table_format = table_format, style = style)

Sparse Override

Every field of TableFormat and TableStyle defaults to nothing, meaning "keep the default behavior of the selected back end". Hence, the objects never replace the back end configuration entirely: each set field overrides only the corresponding field of the back end default format or style. For example, the following object only adds horizontal lines between the data rows, keeping everything else untouched in every back end:

julia> pretty_table([1 2; 3 4]; table_format = TableFormat(horizontal_lines_at_data_rows = :all))┌────────┬────────┐
│ Col. 1 │ Col. 2 │
├────────┼────────┤
│      1 │      2 │
├────────┼────────┤
│      3 │      4 │
└────────┴────────┘

Notice that nothing differs from :none in the fields that accept a Symbol: nothing keeps the back end default, whereas :none explicitly disables the lines.

Table Format

Line Presence

The line presence fields of TableFormat select which lines are drawn. They have the same names as the corresponding fields of the table formats of the text, LaTeX, Typst, and Excel back ends:

• horizontal_line_at_beginning
• horizontal_line_after_column_labels
• horizontal_line_at_merged_column_labels
• horizontal_lines_at_data_rows (:all, :none, or a vector of row indices)
• horizontal_line_before_row_group_label
• horizontal_line_after_row_group_label
• horizontal_line_after_data_rows
• horizontal_line_before_summary_rows
• horizontal_line_after_summary_rows
• vertical_line_at_beginning
• vertical_line_after_row_number_column
• vertical_line_after_row_label_column
• vertical_lines_at_data_columns (:all, :none, or a vector of column indices)
• vertical_line_after_data_columns
• vertical_line_after_continuation_column

The backend-specific fields (for example, horizontal_lines_at_column_labels of the text back end and horizontal_line_between_column_labels of the Excel back end) are not part of TableFormat and remain available in the native table formats.

Line Design

The design of each line is described by a LineStyle, a backend-agnostic description converted to the native line design of each back end. A LineStyle has three fields, all defaulting to nothing (keep the back end default):

• style: :solid, :dashed, :dotted, or :double.
• width: :thin, :medium, or :thick.
• color: a named color (Symbol), a 24-bit color (UInt32 or "#rrggbb"), a tuple (r, g, b), or a SimpleColor.

The line roles follow the border fields of the Typst and Excel table formats:

• top_line, header_line, merged_header_cell_line, middle_line, and bottom_line for the horizontal lines.
• left_line, center_line, and right_line for the vertical lines.

The conversion functions can also be called directly:

julia> typst_line_style(LineStyle(; style = :dashed, width = :thick, color = :red))"(thickness: 1.5pt, paint: rgb(\"#a51c2c\"), dash: \"dashed\")"
julia> excel_line_style(LineStyle(; style = :dashed, color = 0xff0000))2-element Vector{Pair{String, String}}:
 "style" => "dashed"
 "color" => "FFFF0000"
julia> latex_line_style(LineStyle(; style = :double))"\\hline\\hline"

Table Style

A TableStyle describes the decoration of each table section with a Face, exactly like the keyword constructors of the native table styles (see Faces). The available fields are the ones shared by the back end style types: title, subtitle, row_number_label, row_number, stubhead_label, row_label, row_group_label, first_line_column_label, column_label, first_line_merged_column_label, merged_column_label, summary_row_label, summary_row_cell, footnote, and source_note. The fields first_line_column_label and column_label also accept a vector with one face per column.

julia> style = TableStyle(; first_line_column_label = Face(; slant = :italic, foreground = :blue));
julia> pretty_table([1 2; 3 4]; style = style)┌────────┬────────┐
│ Col. 1 │ Col. 2 │
├────────┼────────┤
│      1 │      2 │
│      3 │      4 │
└────────┴────────┘

The backend-specific style fields (for example, table_border of TextTableStyle and data_cell of ExcelTableStyle) are not part of TableStyle and remain available in the native table styles.

Back End Support

The conversion is a best effort: aspects a back end cannot express are silently ignored. The following table summarizes the support:

1. Markdown only supports horizontal_line_before_summary_rows.
2. The text back end maps the designs to Unicode box-drawing characters, which only have light and heavy weights (:medium maps to heavy) and no heavy double lines. The intersections between the lines are selected automatically from the crossing designs, falling back to the characters in TextTableBorders when Unicode does not provide the required character. The line design colors are converted to the line faces of TextTableStyle.
3. The LaTeX dashed and dotted rules use \hdashline, which requires the package arydshln in the document. The designs of the merged header cell line and of the vertical lines cannot be changed.
4. Typst strokes have no double variant, so :double falls back to :solid.
5. Markdown ignores title, subtitle, first_line_merged_column_label, and merged_column_label because its style type does not have those fields.

Additional notes:

• The HTML back end currently ignores TableFormat entirely. The table lines can be customized with the field css of HtmlTableFormat.
• In the text back end, the color of each line follows the precedence: the line face in TextTableStyle (for example, middle_line), the color of the line design, and the face in the field table_border of TextTableStyle.