# Length of list not working?

Someone please help me figure out what I'm doing wrong. I want to count the number of non-empty cells in a particular range in Column A. However, Column B uses Column A in its calculations. The cells in B are fixed so my students can't accidentally erase the formulae.

I am trying to calculate/count the non-empty cells in Column A like this:

l3 = Length(Flatten(l1)) where l1 is the range of cells from A2 to A116.

I keep getting 115. I've tried changing the formula in a number of ways but the result is always 115 - even when it logically can't be:

l3 = Length(Flatten(l1 = 0)) Answer: 115

l3 = Length(Flatten(0 - l1 < 0)) Answer: 115

l3 = Length(Flatten(0 - l1 > 0)) Answer: 115

I've also tried Length(Flatten({A2:A200<0})) and Length(Flatten({A2:A200>0})) but they also yields 115.

It seems like is must be because Geogebra is automatically putting a ? in each empty cell in Column A, but I don't know how to get around it. I need this to behave properly because there are certain features that I don't want to appear until the students have a minimum number of data points.

Can someone please help me solve the mystery, because I'm completely stumped.

Zack

try:

Length(RemoveUndefined(A2:A116))

or (better) if you do not know exactly how long at maximum, but certainly smaller than...

Length(RemoveUndefined(A2:A200))

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Note:

If an object does not appear in the algebraview (not even as auxiliary) then it would be empty/not exists

it is not possible in GGB script to test an object/cell for "empty" or "not exits".

Undefined == ? is not the same as empty/not exists

Testing an object for "undefined" is possible with "! IsDefined(<object>)"

Referencing non-existing objects is basically not possible in ggb, not even in the spreadsheet. Therefore, GGB automatically creates an object for a cell with the value "?" == undefined when an empty cell is referenced from another cell (only inside the spreadsheet)

Perfect! That worked beautifully! Thank you so much. I would have been scratching my head for a very long time trying to figure that one out.

Zack

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