I need the precise sum of areas for a polygon layer, where I have the area values in an attribute. When I use the Statistical Summary window it shows the sum in exponential notation:

Statistic   Value
Count       232
Sum         6.68428e+06
Mean        28811.6
Median      19993.4

At first I thought it was a display issue related to column width, but no. And I hoped that copy-paste might reveal the true value, but also no.

The Area values have 11 decimal places. Can I get the sum to be the same degree of precision as the original data? (I don't actually need 11dp, but I would like to choose for myself the precision to report, rather than have QGIS dictate!)

There is an excellent answer to a previous related question (Summing data from column in Attribute table) but it does not mention this issue. I am using QGIS 3.10.10.

  • 3
    I guess you mean "how do I format the numbers with specified decimal places". The mean suggests original data is 1 decimal place in numbers that have whole 5 digits. Hence the decimal place is probably irrelevant anyway in terms of the precision of the measuring system. It is at best +/- 0.04%. By the way, there is nothing "imprecise" about the exponential notation. it just means 6,684,280. I cannot imagine when one or more decimal places would add value to a number of this magnitude but perhaps there are in some disciplines (it is +/- 0.00001 %). Jan 15, 2021 at 23:16
  • I agree that the error is small and ultimately inconsequential. I am trying to match answers (for a student exercise) between both Arc and Q, as we have students using both. Arc gives me the sum in the same format as the individual values (11dp). Jan 16, 2021 at 10:33
  • 1
    (The student exercise does go on to discuss precision, which is why it's useful to start with an excess of digits purely for illustrative purposes!) Jan 16, 2021 at 10:43


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