Formatting number to 2 digits; just cosmetics ;-)

[pvkan]

Hi,

I use the ‘Wasmachine’ flow to be noticed when the washingmachine has finished.
As an addition i also calcultate the costs of the power used.
With mathjs i round this calculation to 2 digits behind the separator.

Sometimes the calculation gives 20 cents. This is noted as € 0,2 in the message i send to myself.
Just for cosmetic reasons: Is there a way to format this into € 0,20 (2 digits so with the 0 added) in mathjs ? (number to string)
Like something as: usedpower$ = format$(number, € ##,00)

Peter

[robertklep]

If Homey supports all of MathJS, you should be able to use this:

format(VALUE, { precision: 2 })

This will also perform the rounding operation.

[pvkan]

@robertklep

Thanks for the quick repsonse; unfortunatly it does not work; Homey does not recognize ‘format’.

Yhx
Peter

[Wessel]

Maybe round will work:
From @Canedje:
something like this wil work:
{{round (Energiekosten vandaag,2)}}

the 2 means 2 digits after the ,

in your case {{round(Target temperature,1)}}

[robertklep]

He already used round(), but that function will drop any trailing zero’s.

[pvkan]

Yep, using it already.

Round does not ‘format’ the number.

Peter

[Marcel_Ubels]

Maybe adding 0.000001 to the outcome, than Round and extract 0.000001. Maybe you have to round it again.

[Peter_Kawa]

Hi all.

About the format() funtion. It looks like it isn’t supported?
I’m no coder, so be warned
Maybe Robert knows what I’m doing wrong here?

I want a number to be formatted as n.0 (always display the zero) and found this at math.js:

math.format(2.3,  {notation: 'fixed', precision: 4})  // returns '2.3000' 

(In case of notation ‘fixed’, precision defines the number of significant digits after the decimal point)
So, with this Logics card ‘calc a value’, I want to accomplish 100 to be shown as 100.0 like this, but I get NaN values returned.

• I tried this:

{{format(100, { notation: 'fixed', precision: 1 })}}
{{format(100, { 'fixed', precision: 1 })}}
{{format(100, { fixed, precision: 1 })}}
{{format(100, { precision: 1 })}}
{{format(100, { 1 })}}

Something else:
This should round to 1000, but it also returns NaN:

{{format(1234, 2)}}

Background of what I’d like to accomplish:

• Vars used:
• • <W3_Luchtdruk/10> - a Logics NumericVar
• • <Druk> - a value between 0 and 2000 form a airpressure sensor
    VirtualDevice type Thermostat - should display 100.5 or 100.0 as airpressure

Calculate <W3_Luchtdruk/10>
as

{{format(<Druk>/10, { notation: 'fixed', precision: 1 })}}

Flow:

[robertklep]

@Peter_Kawa

This should round to 1000, but it also returns NaN:

{{format(1234, 2)}}

Not sure what you’re doing wrong, that works just fine for me:

and the result:

What also works is this:

{{ format(1234, { precision : 1, notation: "fixed" }) }}

If you use single quotes (or back quotes) it stops working. I guess Athom still hasn’t worked out the parsing issues in flow cards.

[Peter_Kawa]

Thanks, Robert. Glad to know the function itself works.

I can’t see the difference either.
I will continue trying, maybe creating a new flow might help.
Cheers

[Peter_Kawa]

This worked for me as well, Robert, using the math directly in the push message

I found out it doesn’t work with the native logic “calculate a value” card, the result is an empty num var:

But, it works a little bit with better logic “Execute matjs expression” card, but the result stays zero

Again, in the push message it works fine.

Now I have to find out how to get the calculated value into the virtual thermometer…

[robertklep]

Perhaps try variable names without mathematical operators (-) in their names.

[Peter_Kawa]

Thanks Robert. I realized this and changed the var name a few times.
First I used a / sign and before that a . sign. Will now try without special characters.

[Nigel_Scott]

Is there a way to get the output to exclude the " "
I am wanting to turn a number (23) into 23.0 but the results outputs as “23.0” and the web command then fails.

[robertklep]

It seems that the flow cards are adding these (possibly because they are using some sort of JSON formatting). I don’t know if there’s a way of removing them.

[Erlend63]

This is a follow-up to the thread Formatting number to 2 digits; just cosmetics , I have a similar requirement I would like to implement. I have a number variable with multiple digits that I want to assign to a string variable with control of the format. In Perl (yes, old guy here…), this would look like this:

my $fEnergyDiff=1.23456789;
my $strEnergyDiff=sprintf(“%.2f”,$fEnergyDiff);
printf “diff=$strEnergyDiff\n”;

This would produce the string “diff=1.23”. If I can do this in a Homey flow, I can use the string variable (strEnergyDiff) everywhere I need it, for example in log entries or in push messages.

Here is the test flow I have for this:

When I run this, I get this in the Timeline: “fEnergyDiff=1.23456789, strEnergyDiff=1.23456789" (from step #3), as expected.

So, is it possible to do some clever JS stuff in step #2 so that the string variable will be assigned 1.23 and I get “fEnergyDiff=1.23456789, strEnergyDiff=1.23" in the Timeline? I did try some of the suggestions in the linked thread, but got nowhere.

[Adrian_Rockall]

Have you tried using:

const stringObj = numObj.toFixed(2)

[Erlend63]

Well, I tried, but I am pretty sure I did not do this correctly:

This produced the following in the Timeline: “fEnergyDiff=1.23456789, strEnergyDiff={{1.23456789.toFixed(2)}}”.

What is the syntax for using the toFixed function on the fEnergyDiff object and assign it to strEnergyDiff?

[Adrian_Rockall]

I think you will need to use the calculate card to round the number and then convert that to text.

[Erlend63]

Thanks, this seems to work fine:

When I run this, card #2 does the rounding and card #4 produces the correct 2-decimal numbers in the Timeline. Since Num already has 2-decimals (due to the round function), I don’t really need the Str variable (card #3).

I found during this testing that card #1 doesn’t work, the setting of this variable is ignored, the calculation in card #2 uses the value I set in the web interface instead (from the Variables button in the flow editor), card #1 is ignored. I am not sure why this happens - maybe somebody can explain it.

Anyway, thanks Adrian - your tip did the trick! /Erlend