MAT5335 Project 2 due Friday January 27
We will also be considering the data from class, DF.

1. Consider the Columbia River Estuary dataset, but for SATURN 03 June 2016 Salinity at 2.4m.

1a. Import the data into R, name it DF2016.

1b. What are the dimensions of each data frame DF and DF2016?  You should notice there are more rows in DF than in DF2016.

1c. Find the average water salinity for both and compare the two.

1d. Use the strptime function  to convert the first column of the data into numerical times that R can easily handle, but can you find an easier way to do this? What type of object is this?  Name it timevec2016.

2a. What does the following input return, i.e., what is it telling us?
sort(table(diff(timevec2016)),decreasing=TRUE)

2b. What happens if we remove sort?

2c. Does it make any difference if we replace TRUE with T, true, True?

2d. Is we replace decreasing=TRUE with decreasing=FALSE, is that the same as increasing=TRUE?

2e. List the ten longest and shortest time differences between consecutive measurements, as well as the mean of the time differences. 

2f. When did the maximum time difference occur?  Approximately when did the mean time difference occur? 

3a. Sketch the plot, of DF2016, water salinity vs water temperature.  

If you get any errors while trying to plot, see par, options, or dev.off() which will delete all your plots.

3b. Sketch your plot again but in red, from x=10 to x=20, label your x and y axis, place a tick mark at every integer, and give your plot a name.

4. Visit www.ssa.gov, top US baby names from 1880 to 2015. Each year is a separate file, we will combine the files in class. tapply will be helpful.

Consolidating data frames in R.
http://stackoverflow.com/questions/9807945/consolidating-data-frames-in-r

4a. Find the total number of babies born by gender.

4b. Find the sum of babies born in each decade (1880-1889, 1890-1899,…, 2010-2015). 

4c. Find the sum of babies born in each decade by gender.

4d. Find the sum of babies born per year.

4e. Find the sum of babies born after 1990.

4f. Find the top ten female (and male) names overall.

4g. Find the top ten female (and male) names in a particular year.

4h. (optional) Find the top ten female (and male) in each decade.

5. Which data type in R can hold different type of elements? 
Is it vectors, matrices, arrays, or data frames? Pick one.