Update README.md

README.md

 # dataCleaning
 
-A place to store hints, tips and examples for data cleaning. We use a lot of very dirty data.
+A place to store hints, tips and examples for data cleaning. We use a lot of very dirty data which often has outliers and missing observations. Since most of this data is large scale 'sensor' data with time stamps we make a lot of use of t hese R packages:
+
+ * [data.table](https://rdatatable.gitlab.io/data.table/)
+ * [lubridate](https://lubridate.tidyverse.org/)
+ * [hms](https://hms.tidyverse.org/)
+ * [ggplot2](https://ggplot2.tidyverse.org/)'s [geom_tile()](https://ggplot2.tidyverse.org/reference/geom_tile.html) with time of day on the date on the x axis, time on the y and 'fill' set to the sensor value that _should_ be there. This shows up non-random (and random) data holes like [these](https://git.soton.ac.uk/SERG/datacleaning/-/blob/master/rmd/cleaningFeederData_files/figure-latex/missingVis-1.pdf) very nicely.
 
 This repo is an R package. This means: