R Programming Language Multiple Choice Questions on “Packages ”.
1. ______ let’s you perform SQL queries on your R data frames.
a) sqldf
b) plyr
c) forecast
d) daply
Answer: b
Clarification: sqldf uses SQLite syntax. Plyr will split-apply-combine paradigm for R. Forecast is a generic function for forecasting from time series or time series models. The function invokes particular methods which depend on the class of the first argument.
2. ______ splits a data frame and results an array (hence the da). Hopefully you’re getting the idea here.
a) apply
b) daply
c) stats
d) plyr
Answer: b
Clarification: ddply splits a data frame and returns a data frame.
3. ________ makes it incredibly easy to fit time series models like ARIMA, ARMA, AR, Exponential Smoothing, etc.
a) sqldf
b) plyr
c) forecast
d) stats
Answer: c
Clarification: Most important feature is the resulting forecast plot.
4. ________ provides needed string operators in R.
a) str
b) forecast
c) stringr
d) sqldf
Answer: c
Clarification: stringr is remarkably easy to use.
5. Which of the following syntax is used to install forecast package?
a) install.pack(“forecast”)
b) install.packages(“cast”)
c) install.packages(“forecast”)
d) install.pack(“forecastcast”)
Answer: c
Clarification: forecast is used for time series analysis.
6. Which of the following is similar to Moment.js?
a) stringr
b) lubridate
c) ploy
d) forecast
Answer: b
Clarification: lubridate is one of those magical libraries that just seems to do exactly what you expect it to.
7. Which of the following is a library for statistical quality control?
a) gcc
b) qcc
c) anc
d) pnc
Answer: b
Clarification: qcc can help you monitor transaction volumes, visitors or logins on your website, database operations, and lots of other processes.
8. ______ specializes in converting data from wide to long format.
a) gcc
b) reshape
c) reshape2
d) gcc2
Answer: c
Clarification: reshape2 is used in conjunction with ggplot2 and plyr.
9. _________ is used to convert wide data to long data.
a) melt
b) dcast
c) cast
d) rcast
Answer: a
Clarification: dcast is used to go from long to wide.