KH.selectByMin: Select rows based on minimum a valuein a given column
In ks465/r-utils: A Collection of Wrappers for Frequently Used Codes

Description Usage Arguments Details Value See Also Examples

Select rows based on minimum a valuein a given column

1	KH.selectByMin(DT, groupBy, selectByMinOf)

`DT`	data.table. Data object wich has at least one string / factor column and one numeric colum.
`groupBy`	character or vector of characters. Name of column to use for grouping rows of data. If this is set to `NULL`, a single row containing `MIN(selectByMinOf)` will be returned.
`selectByMinOf`	character. Name of column to calculate `MIN()`.

This function groups rows of input data according to groupBy value and filter the codeMIN(selectByMinOf) for each group.

data.table. data.table oject with the same columns as input data set and rows containing the minimum of target column.

Other Datasets: KH.selectByMax

{
input_file <- system.file("extdata", "input_file.csv", package = "KHanSUtils")
DT <- KH.loadCSV(input_file)
DT

#    year month day dep_delay arr_delay carrier origin dest air_time distance hour
# 1: 2014    10  31        -4        15      MQ    LGA  DTW       75      502   11
# 2: 2014    10  31        -8        16      MQ    LGA  RDU       83      431   11
# 3: 2014    10  31        -5         1      MQ    LGA  SDF      110      659    8
# 4: 2014     1   1        -8       -26      AA    LGA  PBI      157     1035    7
# 5: 2014    10  31        -5       -14      UA    EWR  IAH      189     1400    8
# 6: 2014    10  31         1       -30      UA    LGA  IAH      201     1416   14
# 7: 2014     1   1         4         0      AA    EWR  LAX      339     2454   18
# 8: 2014     1   1         2         1      AA    JFK  LAX      350     2475   13
# 9: 2014     1   1         2         9      AA    JFK  LAX      351     2475   19
#10: 2014     1   1        14        13      AA    JFK  LAX      359     2475    9
#11: 2014     1   1        -3        13      AA    JFK  LAX      363     2475   11

groupBy <- c('carrier','origin')
selectByExtOf <- 'air_time'

KH.selectByMin(DT,groupBy, selectByExtOf)

#    carrier origin year month day dep_delay arr_delay dest air_time distance hour
# 1:      AA    EWR 2014     1   1         4         0  LAX      339     2454   18
# 2:      AA    JFK 2014     1   1         2         1  LAX      350     2475   13
# 3:      AA    LGA 2014     1   1        -8       -26  PBI      157     1035    7
# 4:      MQ    LGA 2014    10  31        -4        15  DTW       75      502   11
# 5:      UA    EWR 2014    10  31        -5       -14  IAH      189     1400    8
# 6:      UA    LGA 2014    10  31         1       -30  IAH      201     1416   14
}