R DATE TIME and FACTORS
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R provides several options for working with dates and times. Date objects represent dates as the number of days since January 1, 1970 and support operations like adding or subtracting days. Time objects like POSIXct and POSIXlt store both dates and times, with the ability to specify time zones. The lubridate package offers convenient functions for parsing date-time strings and performing arithmetic on date-time components. Factors are R's data type for categorical variables and allow specifying labels, levels, and changing or reordering levels to control how categorical data is displayed and analyzed.
R DATE TIME and FACTORS
- 2. DATES IN R • Date objects • Using as.Date – converts a string into integer • Number of days from 01/01/1970 • Using your own epoch in as.Date • Sequence function • Date + Time objects • as.POSIXct – suitable for data frames • as.POSIXlt – human readable • Uses machines time zone • Time zone may be specified
- 3. DATES IN R • Operations of date objects • Weekdays, months, quarters • diff • difftime
- 4. LUBRIDATE • Special functions • ymd, mdy, dmy • hms, hm • ymd_hm • seconds, months, years • Arithmetic operations • Explicitly specify units
- 5. CATEGORICAL DATA (FACTORS) • Factors – data type for handling categorical data • Labels • Levels • Creation • Using factor function • Label and level are determined alphabetically • Levels can be user-specified • Changing the levels • Reordering the levels • Reducing the levels
- 6. CATEGORICAL DATA (FACTORS) • Creating factors from continuous data
Editor's Notes
- #3: For effectively using R for gaining insights from data one needs to have working knowledge of the standard data types and data structures in R.
- #4: For effectively using R for gaining insights from data one needs to have working knowledge of the standard data types and data structures in R.
- #5: For effectively using R for gaining insights from data one needs to have working knowledge of the standard data types and data structures in R.
- #6: For effectively using R for gaining insights from data one needs to have working knowledge of the standard data types and data structures in R.
- #7: For effectively using R for gaining insights from data one needs to have working knowledge of the standard data types and data structures in R.