[R] Convert txt file to time series and conduct trend and wavelet analyses

johnhammondplease hammondj at science.oregonstate.edu
Wed Jan 29 07:11:42 CET 2014


I have many .txt files all with the same format, one column for date
(yyyy/mm/dd), another column for discharge (numerical values from 0.00 to
500.00), and two coulmns that I do not need. I am working in R.

I am looking to import this data with values for date and discharge,
possibly convert the data to a time series, and then run Mann-Kendall trend
tests and linear regressions on the discharge values.

I am interested in testing for trend on the full period of record in my data
which is longer than 50 years, but I would like to test for trend by day of
year. For example, I would be looking at discharge on January 1st for every
year from 1950 to 2012. The I would want to test Jan 2 discharge for the
period 1950 to 2012. How would I parse the data into data for just the day
of the year for 52 years in order to run a trend test for each day of the

If I were also interested in only looking at trend in day of year discharge
for example 1960 to 2000, how could I go about doing this?

Thank you very much, your help will be very greatly appreciated!

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