Question

I have a data frame like this:

Date Impacting_APP     Impacted_APP
1/1/2012    PS                PayRoll
1/2/2012    PS                Web
1/3/2012    PS                HR
1/10/2012    Trading           PS
2/1/2012    Trading           PS
3/1/2012    Trading           PS
5/1/2012    PS                Payroll
8/1/2012    PS                Payroll
8/1/2012    PS                Payroll

etc

I need to summarize this data frame like below:

 Impacted_APP     Impacting_APP  Count
    PayRoll          PS             4
    PS               Trading        3

can somebody start me with this? Any ideas I can how I can summarize this data set?

Answer 1

The as.data.frame.table function will take table-data objects and recast them into long format.

with( dfrm, as.data.frame( table( Impacting_APP  , Impacted_APP) ) )

   Impacting_APP Impacted_APP Freq
1             PS           HR    1
2        Trading           HR    0
3             PS      Payroll    3
4        Trading      Payroll    0
5             PS      PayRoll    1
6        Trading      PayRoll    0
7             PS           PS    0
8        Trading           PS    3
9             PS          Web    1
10       Trading          Web    0

Note: the failure to match your answer was due to two variants of the factor level “Payroll” and “payroll”. Changing the input data and the order of arguments to table produces:

  Impacted_APP Impacting_APP Freq
1           HR            PS    1
2      Payroll            PS    4
3           PS            PS    0
4          Web            PS    1
5           HR       Trading    0
6      Payroll       Trading    0
7           PS       Trading    3
8          Web       Trading    0

After assigning to ‘counts.df’ this code would adress the desire in the comment for selective display of the results:

counts.df <- with( dfrm, as.data.frame( table( Impacted_APP, Impacting_APP ) ) )
subset(counts.df, Impacted_APP=="Payroll" & Freq>0)
#----------------------------------#
  Impacted_APP Impacting_APP Freq
2      Payroll            PS    4