Finding number of empty cells in a table column?

Authoring Inform 7
1

To build on Number of Entries in a Column, I was wondering if there was a way to be able to count empty entries in a specific column. I thought I was getting close, but I keep getting an error.

table of random examples
c1	c2	c3	c4
1	2	3	4
--	--	--	5
1	--	--	6
2	3	--	7

every turn:
	say "[empty-cells of table of random examples and c1 column].";
	say "[empty-cells of table of random examples and c2].";
	say "[empty-cells of table of random examples and c3].";
	say "[empty-cells of table of random examples and c4].";

to decide which number is empty-cells of (tn - a table name) and (tc - a table column):
	let temp be 0;
	repeat through tn:
		unless there is a tc entry, increment temp;
	decide on temp;

This can be done without the “to decide” function, but I was wondering if I was missing some syntax that would let empty-cells work?

Currently I’m getting

Problem. In the sentence 'if there is a tc entry'  , I was expecting to read a value, but instead found some text that I couldn't understand - 'a tc entry'.
Problem. You wrote 'if there is a tc entry'  , but 'a tc entry' is a value, not a reference to an entry in a table.

Can I do better? Thanks!

2

The only way I see to do it in I7 is to handle the column manually:

	repeat through tn:
		if tc is c1:
			unless there is a c1 entry, increment temp;
		if tc is c2:
			unless there is a c2 entry, increment temp;
		if tc is c3:
			unless there is a c3 entry, increment temp;
		if tc is c4:
			unless there is a c4 entry, increment temp;

This is a cobbled-together I6 definition that works:

To decide whether table cell exists in/from (TC - table column): (- ExistsTableLookUpEntry({-my:ct_0}, {TC}, {-my:ct_1}) -).

[...]

	repeat through tn:
		unless table cell exists in tc, increment temp;

This gets into undocumented stuff and may not work in future releases.

2 Likes
3

Neat! Thanks especially for the I6 tip. I always appreciate the nudge to look into that more.