Question

Task 1: Read each row from one csv file into one seprate txt file.

Task 2: Reverse: in one folder, read text from each txt file and put into a row in a single csv. So, read all txt files into one csv file.

How would you do this? Would Java or Python be good to get this task done in very quickly?

Update:
For Java, there are already some quite useful libraries you can use, for example opencsv or javacsv. But better have a look at wikipedia about csv if no knowledge on csv. And this post tells you all the possibilities in Java.

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Note: Due to the simplicity of the question, some one pre-assume this is a homework. I hereby declare it is not.

More background: I am working on my own experiments on machine learning and setting up a large scale test set. I need crawl, scrape and file type transfer as the basic utility for the experiment. Building a lot of things by myself for now, and suddenly want to learn Python due to some recent discoveries and get the feeling Python is more concise than Java for many parsing and file handling situations. Hence got this question.

I just want to save time for both you and me by getting to the gist without stating the not-so-related background. And my questions is more about the second question “Java vs Python”. Because I run into few lines of code of Python using some csv library (? not sure, that’s why I asked), but just do not know how to use Python. That are all the reasons why I got this question. Thanks.

Answer 1

From what you write there is little need on using something specific for CSV files. In particular for Task 1, this is a pure data I/O operation on text files. In Python for instance:

for i,l in enumerate(open(the_file)):
   f = open('new_file_%i.csv' % i, 'w')
   f.write(l)
   f.close()

For Task 2, if you can guarantee that each file has the same structure (same number of fields per row) it is again a pure data I/O operation:

# glob files
files = glob('file_*.csv')
target = open('combined.csv', 'w')
for f in files:
   target.write(open(f).read())
   target.write(new_line_speparator_for_your_platform)
target.close()

Whether you do this in Java or Python depends on the availability on the target system and your personal preference only.