Jinja2 round filter not rounding

Question:

I have the following code in my template:

data: [{% for deet in deets %} {{ deet.value*100|round(1) }}{% if not loop.last %},{% endif %} {% endfor %}]

I am expecting data rounded to 1 decimal place. However, when I view the page or source, this is the output I’m getting:

data: [ 44.2765833818,  44.2765833818,  44.2765833818,  44.2765833818,  44.2765833818,  44.2765833818,  44.2765833818,  44.2765833818,  44.2765833818,  44.2765833818 ]

This is not rounded to 1 decimal place. It runs without a template error or anything, but produces incorrect output. My understanding from the documentation, and even a related stack overflow question, are that my format should work. What am I missing or doing wrong?

Asked By: Mittenchops

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Source

Answers:

Didn’t realize the filter operator had precedence over multiplication!

Following up on bernie’s comment, I switched

{{ deet.value*100|round(1) }}

to

{{ 100*deet.value|round(1) }}

which solved the problem. I agree the processing should happen in the code elsewhere, and that would be better practice.

Answered By: Mittenchops

You can put parens around the value that you want to round. (This works for division as well, contrary to what @sobri wrote.)

{{ (deet.value/100)|round }}

NOTE: round returns a float so if you really want the int you have to pass the value through that filter as well.

{{ (deet.value/100)|round|int }}
Answered By: John R

I ran across this… needed int(mem_total / 4) in jinja. I solved it by making it two operations:

{% set LS_HEAP_SIZE = grains['mem_total'] / 4 %}
{% set LS_HEAP_SIZE = LS_HEAP_SIZE | round | int %}
Answered By: Dan Garthwaite

Try this

{{ (deet.value*100)|round(1) }}

If we didn’t put parenthesis, round will do only to 100 not to the result.

Answered By: Dithon

If filter operator has precedence, then you should use round(3) instead of round(1) in “{{ 100*deet.value|round(1) }}”

Answered By: Denis Shulyaka