I would not count on order preserving nature of the operations, because it is not guranteed. I would assign some order to the sentences and sort at the end before write back

On Fri, 27 Jan 2017 at 10:59 pm, Md. Rezaul Karim <rezaul.karim@insight-centre.org> wrote:
Some operations like map, filter, flatMap and coalesce (with shuffle=false) usually preserve the order. However, sortBy, reduceBy, partitionBy, join etc. do not.

Regards,
_________________________________
Md. Rezaul Karim, BSc, MSc
PhD Researcher, INSIGHT Centre for Data Analytics
National University of Ireland, Galway
IDA Business Park, Dangan, Galway, Ireland

On 27 January 2017 at 09:44, Soheila S. <soheila518@gmail.com> wrote:
Hi All,
I read a test file using sparkContext.textfile(filename) and assign it to an RDD and process the RDD (replace some words) and finally write it to a text file using rdd.saveAsTextFile(output).
Is there any way to be sure the order of the sentences will not be changed? I need to have the same text with some corrected words.

thanks!

Soheila

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Best Regards,
Ayan Guha