How to divide a custom column value?

[Vianney]

Hello everyone,

I'm new to this forum so I hope I'm in the good place for this question.

I use the Countpage plugin which displays the number of words of a epub in a custom column called "mots".

What I want to do is to display a fraction of this number in another custom column called "durée" (so I can have the reading time of the book, based on my reading speed)

I read some documentation about the calibre templates and functions and I try a lot, but I can't manage to perform this simple operation. I get an error each time i try.

Can anyone explain to me which syntax to use for this operation?

Thanks you very much

Vianney

[BetterRed]

I searched this sub-forum for 'calculate' and found:

How many hours for a book

Calculate reading time.

Moderator Notice

And, I moved your thread here because you must have missed this sticky

PLEASE READ BEFORE POSTING - Purpose of Development subforum

BR

[thiago.eec]

Originally Posted by Vianney

Hello everyone,

I'm new to this forum so I hope I'm in the good place for this question.

I use the Countpage plugin which displays the number of words of a epub in a custom column called "mots".

What I want to do is to display a fraction of this number in another custom column called "durée" (so I can have the reading time of the book, based on my reading speed)

I read some documentation about the calibre templates and functions and I try a lot, but I can't manage to perform this simple operation. I get an error each time i try.

Can anyone explain to me which syntax to use for this operation?

Thanks you very much

Vianney

I believe this is what you are asking for:

program:
	reading_time = divide(raw_field('#mots'), 50);
	h = format_number(subtract(reading_time, fractional_part(reading_time)),  '{0:0>2.0f}');
	m = format_number(multiply(fractional_part(reading_time), 60), '{0:0>2.0f}');
	reading_time = strcat(h, 'h ', m, 'm')

Use the template above on your 'durée' column. The value in red on the first line represents your reading speed in pages/hour. Just change it accordingly.

P.S.: I formatted the result to be more human readable. Ex.: '12.8' becomes '12h 48m'.

Edit: You acctually mentioned words, not pages. But it works just the same. Just use your speed in words/hour.

[chaley]

Originally Posted by thiago.eec

program:
	reading_time = divide(raw_field('#mots'), 50);
	h = format_number(subtract(reading_time, fractional_part(reading_time)),  '{0:0>2.0f}');
	m = format_number(multiply(fractional_part(reading_time), 60), '{0:0>2.0f}');
	reading_time = strcat(h, 'h ', m, 'm')

And just for fun, using the recent changes to the template language:

program:
	reading_time = (if $$#mots == 'none' then 0 else $$#myfloat fi) / 50;
	h = format_number(floor(reading_time), '{0:0>2.0f}');
	m = format_number(fractional_part(reading_time) * 60, '{0:0>2.0f}');
	reading_time = strcat(h, 'h ', m, 'm')

The strange 'if' on line 2 is there because I found a bug in calculating binary operators like '/'. Undefined raw fields don't work. I will fix that. After I fix it the line would be

	reading_time = $$#mots / 50;