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.



def csv = []
def loadCsv = { source -> source.splitEachLine(/,/) { csv << it.collect { it } } }
def saveCsv = { target -> target.withWriter { writer -> csv.each { writer.println it.join(',') } } }
 
loadCsv new File('csv.txt')
csv[0][0] = 'Column0'
(1..4).each { i -> csv[i][i] = i * 100 }
saveCsv new File('csv_out.txt')