Hi,

I want to partition dataframe and then combine to find multiples or divisions of columns in partition.

My example such: to calculate area sums (column square), price sums and get price per square.

I was unable to do this using combine despite combine would be preferred method.

Get some success in more complicated way, but can not calculate number of rows.

Any solutions ?

Thanks,

Edvard

```
# Sample DataFrame
df = DataFrame(
Size = ["A", "B", "A", "B"],
Price = [1000000, 2000000, 3000000, 4000000],
Square = [100, 200, 150, 250]
)
# Group by "Size"
partitions_by_size = groupby(df, :Size)
# Define a custom function to calculate PriceM2 within a partition
function calculate_priceM2(partition)
return sum(partition.Price) / sum(partition.Square)
end
# Calculate "Kaina_sum_mln" and "KainaM2" within each partition using the custom function
data_by_size = DataFrame(
Size = unique(df.Size),
# nrow = nrow(partitions_by_size),
# nrow => count,
Price_sum_mln = combine(partitions_by_size, :Price => (price -> sum(price) / 1000000)),
PriceM2 = [calculate_priceM2(partition) for partition in partitions_by_size]
)
```