[R] sum specific rows in a data frame

[Mohamed Lajnef]

Hi Arnaud,

Try  aggregate function

regards
M

arnaud Gaboury a écrit :
> I have a data frame called "pose":
>
>
>           DESCRIPTION QUANITY CLOSING.PRICE
> 1       WHEAT May/10        1        467.75
> 2       WHEAT May/10        2        467.75
> 3       WHEAT May/10        1        467.75
> 4       WHEAT May/10        1        467.75
> 5 COTTON NO.2 May/10        1         78.13
> 6 COTTON NO.2 May/10        3         78.13
> 7 COTTON NO.2 May/10        1         78.13
>
> I would like to sum the quantity for each category (i.e WHEAT and
> COTTON),but I have no idea how to write it in a simple manner. The number or
> rows will change every day.
> TY for any help.
>
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>   


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