Change date column to integer - date

Question

I have a large csv file as below:
DATE status code value value2
2014-12-13 Shipped 105732491-20091002165230 0.000803398 0.702892835
2014-12-14 Shipped 105732491-20091002165231 0.012925206 1.93748834
2014-12-15 Shipped 105732491-20091002165232 0.000191278 0.004772389
2014-12-16 Shipped 105732491-20091002165233 0.007493046 0.44883348
2014-12-17 Shipped 105732491-20091002165234 0.022015049 3.081006137
2014-12-18 Shipped 105732491-20091002165235 0.001894693 0.227268466
2014-12-19 Shipped 105732491-20091002165236 0.000312871 0.003113062
2014-12-20 Shipped 105732491-20091002165237 0.001754068 0.105016053
2014-12-21 Shipped 105732491-20091002165238 0.009773315 0.585910214
:
:
What i need to do is remove the header and change the date format to an integer yyyymmdd (eg. 20141217)
I am using opencsv to read and write the file.
Is there a way where i can change all the dates at once without parsing them one by one?
Below is my code to remove the header and create a new file:
void formatCsvFile(String fileToChange) throws Exception {
CSVReader reader = new CSVReader(new FileReader(new File(fileToChange)), CSVParser.DEFAULT_SEPARATOR, CSVParser.NULL_CHARACTER, CSVParser.NULL_CHARACTER, 1)
info "Read all rows at once"
List<String[]> allRows = reader.readAll();
CSVWriter writer = new CSVWriter(new FileWriter(fileToChange), CSVWriter.DEFAULT_SEPARATOR, CSVWriter.NO_QUOTE_CHARACTER)
info "Write all rows at once"
writer.writeAll(allRows)
writer.close()
}
Please can some one help?
Thanks

Answer 1

You don't need to parse the dates, but you do need to process each line in the file and convert the data on each line you want to convert. Java/Groovy doesn't have anything like awk where you can work with file data as columns, for example, the first 10 "columns" (characters usually) in every line in a file. Java/Groovy only deals with "rows" of data in a file, not "columns".
You could try something like this: (in Groovy)
reader.eachLine { String theLine ->
int idx = theLine.indexOf(' ')
String oldDate = theLine.subString(0, idx)
String newDate = oldDate.replaceAll('-', '')
String newLine = newDate + theLine.subString(idx);
writer.writeLine(newline);
}
Edit:
If your CSVReader class is not derived from File, then you can't use Groovy's eachLine method on it. And if the CSVReader class's readAll() method really returns a List of String arrays, then the above code could change to this:
allRows.each { String[] theLine ->
String newDate = theLine[0].replaceAll('-', '')
writer.writeLine(newDate + theLine[1..-1])
}

Answer 2

Ignore the first line (the header):
List<String[]> allRows = reader.readAll()[1..-1];
and replace the '-' in the dates by splitting each row and editting the first:
allrows = allrows.collect{
row -> row.split(',')[0].replace(',','') // the date
+ row.split(',')[1..-1] // the rest
}
I don't know what you mean by "all dates at once". For me can only be iterated.