How to merge two data frames in r by a common column with mismatched date/time values

How to merge two data frames in r by a common column with mismatched
date/time values

References

Reference NO 1

http://stackoverflow.com/questions/15200851/how-to-merge-two-data-frames-in-r-by-a-common-column-with-mismatched-date-time-v

Reference NO 2

http://stackoverflow.com/questions/14731861/merge-data-frames-whilst-summing-common-columns-in-r

Reference NO 3

http://stackoverflow.com/questions/14559401/how-to-merge-two-datasets-in-r-where-one-dataset-has-geometry-variable

Reference NO 4

http://stackoverflow.com/questions/13566982/how-to-partially-replace-data-of-a-column-using-another-date-column-in-r

Reference NO 5

http://stackoverflow.com/questions/18107002/joining-one-column-of-a-data-frame-to-an-existing-data-frame-of-unqual-length-by

Reference NO 6

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Reference NO 7

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Reference NO 8

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