blank

Replaces consecutive identical values in selected columns with a blank string (or a custom value).

Behavior:

• For each selected column, the current value is compared with the value in the previous row.
• If the values are identical, the current cell is replaced with an empty string (or the specified replacement value).
• If the values differ, the current value is written, and it becomes the new reference for subsequent rows.
• Blanking is stateful across file boundaries when multiple files are provided.
• Use -i / --ignore-case to compare values case-insensitively.

Input:

• Reads from files or standard input.
• Files ending in .gz are transparently decompressed.

Header behavior:

• Supports --header / -H and --header-hash1 modes.
• When using header mode with multiple files, only the header from the first file is written; headers from subsequent files are skipped.

Field syntax:

• Use -f / --field to specify columns to blank.
• Format: COL (blank with empty string) or COL:REPLACEMENT (blank with custom string).
• Columns can be specified by 1-based index or, if -H is used, by header name.
• Run tva --help-fields for a full description shared across tva commands.

Output:

• By default, output is written to standard output.
• Use --outfile to write to a file instead.

Examples:

1. Blank the first column tva blank -H -f 1 data.tsv

2. Blank the ‘category’ column with “—” tva blank -H -f category:--- data.tsv

3. Blank multiple columns tva blank -H -f 1 -f 2 data.tsv