[R] Odp: Creating a variable which is the sum of equal rows in a dataframe

[Petr PIKAL]

Hi
r-help-bounces at r-project.org napsal dne 04.05.2009 13:19:15:

> Hi everyone:
> 
> I need to count the number of banks of each firm in my 
> data. The firm is identified by the fiscal number. The 
> banks of each firm appears like this:
> 
> Firm                     Banks
> 500600700          Citybank
> 500600700          CGD
> 500600700          BES
> 500600800          Citybank
> 500600800          Bank1
> 500600900          CGD
> …
> 
> I want to obtain the following dataframe:
> Firm            numberofbanks
> 500600700          3
> 500600800          2
> 500600900          1
> …

E.g.

as.data.frame(rowSums(table(test)))

Regards
Petr

> 
> This is a question of counting the times each firm 
> appears, but I don’t know which function do this. If 
> anyone could help me I appreciate.
> 
> Thank you in advance for the help you could give me,
> 
> Cecilia Carmo (Portugal)
> 
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