# Modify and edit comments and `keyword-value` pairs in FITS header Functions to modify and edit `keyword = value` pairs in FITS header: `newKwv` creates `keyword = value / comment` line for header; `addKwv` adds `keyword = value / comment` to header; `delKwv` deletes `keyword = value / comment` from header; `modVal` modifies value in `keyword = value / comment` in header; `addComment` adds COMMENT line to header; `addHistory` adds HISTORY line to header. ```r newKwv(keyw, val, note) addKwv(keyw, val, note, headerName) delKwv(keyw, headerName) modVal(keyw, val, note, headerName) addComment(comment, headerName) addHistory(history, headerName) ``` ## Arguments - `keyw`: Keyword, 8 character limit (FITS specification) - `val`: Value for keyword - `note`: Optional descriptive note following `keyword = value` - `comment`: Comment text string - `history`: History text string - `headerName`: Header card images (vector) ## Details All keywords will be converted to upper case (FITS convention) and truncated to 8 characters. There is no checking for duplicate keywords. The default numerical format for values is 20.14g; if other formats are needed, format separately and write the text string as the value (see examples). Similar work-arounds may be necessary for long note strings (see examples). ## Returns New card image for `newKwv`, otherwise modified header card images. ## Author(s) A. Harris ## Note It is also possible to operate directly on the vector of header card images. These functions are simply for convenience in maintaining the correct header formatting. No `END` card is needed in the header card images; that is added by `closeHdr`, which must be run to complete the header formatting. ## See Also `readFITS`, `readFITSheader`, `closeHdr` ## Examples ```r # Make header from scratch, then add, modify, delete card images. header <- newKwv('KEYWORD', 'VALUE', 'NOTE') header <- addKwv('test1', 'plot size', header=header) header <- addKwv('test2', 4294.95397809807, 'number', header=header) header <- addKwv('test3', 4.29495397809807e50, 'big number', header=header) header <- addKwv('test4', -4.29495397809807e50, 'big number', header=header) header <- addKwv('test5', 'this is a very long value', 'number', header=header) header <- addKwv('test6', 'this is a very very very very very very very very long value', 'note', header=header) header <- addKwv('test7', 'value', 'very very very very very very very very very very long comment', header=header) header <- addKwv('test8', '0123456789112345678921234567893123456', 'format long number as string', header=header) header <- addKwv('apostrophe', 'o\'\'malley', 'apostrophes are doubled in value strings', header=header) for (i in 1:4) { header <- addKwv(paste('test', 100+i, sep=''), 100+i, header=header) } header <- delKwv('test103', header=header) header <- addComment('TEST103 should be missing from header', header=header) header <- addHistory('This header generated by modifyHeader example', header=header) # show header header ```

modifyHeader function