Merge rows from two CSV files

[stefanaalten]

I'm trying to figure out a way to accomplish the following:

I have a file ("books.csv") generated by an application (ComicRack) which lists books, one per line, unordered, approx. 4,000, as follows: Series;Title;Number;Volume;Year. A new version of this file is produced on an ad hoc basis (when I run the report). I can't change the format of the file (including the ; as field separator) as that's preset by the application.

e.g. Michel Vaillant;Paddock;58;-1;1995

I want to record the "read status" of each book by editing "books.csv", e.g. simply adding a field at the end of each line so it becomes: Series;Title;Number;Volume;Year;Read. Call this file "books-read.csv".

e.g. Michel Vaillant;Paddock;58;-1;1995;read

The list of books in books.csv may change with new books being added, removed, changed.
The only changes to books-read.csv will be when I change the "read" field, so no books will be added, removed or changed (apart from the value of the "read" field).

How can I merge these files on a regular basis?

- Books removed from books.csv should also be removed from books-read.csv, irrespective of whether they have been read or not.
- Books added to books.csv should also be added to books-read.csv, but of course the "read" field will be missing / empty
- Books changed in books.csv should overwrite the matching book in books-read.csv.

Thanks for any help with this!

 

[John_w]

Do you still need help with this?

You want the output to be a new books-read.csv file based on the current books.csv and books-read.csv files. It seems that merging two sorted arrays should work. Start by reading the files into 2 arrays, keeping the "read" field separate so that the records in both arrays can be compared. Then sort both arrays. Then loop through the arrays and merge to a new array, copying the "read" field when the records match. Then output the new array to the new file.