CSV spreadsheet files are suitable for storing tabular data in a relatively portable way.

The CSV format is flexible but somewhat ill-defined.

For present purposes, authors may assume that the data fields contain no commas, backslashes, or quotation marks.



Task

Read a CSV file, change some values and save the changes back to a file.

For this task we will use the following CSV file:

C1,C2,C3,C4,C5
1,5,9,13,17
2,6,10,14,18
3,7,11,15,19
4,8,12,16,20

Suggestions


 Show how to add a column, headed 'SUM', of the sums of the rows.
 If possible, illustrate the use of built-in or standard functions, methods, or libraries, that handle generic CSV files.



csvFile:=File("test.csv");
header:=csvFile.readln().strip(); // remove trailing "\n" and leading white space
listOfLines:=csvFile.pump(List,fcn(line){ line.strip().split(",").apply("toInt") });
 
newFile:=File("test2.csv","w");
newFile.writeln(header + ",sum");
listOfLines.pump(newFile.writeln,fcn(ns){ String(ns.concat(","),",",ns.sum()) });
newFile.close();