Force zeros with percent formatting

Question

I'd like to display a dataframe feature in percentages with 4 decimal places:

scales::percent(1:3/12345)
"0.0081%" "0.0162%" "0.0243%"

This shows each value as a percent to 4 decimal places.

But if I try eg

scales::percent(c(1:3/12345, 0.9), accuracy = 4)
[1] "0%"  "0%"  "0%"  "88%"

I lose the values for the first 3. I'd like those to show as

"0.0081%", "0.0162%" "0.0243%".

How can I force the same number of digits while formatting as percent? I always want 4 digits to the right of the decimal, even if they are all zero.

Answer 1

You can do:

scales::percent(c(1:3/12345, 0.9), accuracy = 0.0001)

[1] "0.0081%"  "0.0162%"  "0.0243%"  "90.0000%"

The accuracy argument has a rather counterintuitive functioning, meaning that if you want to have an output with more decimal places, you need to use a number smaller than 1 (which is also the default value). Every decimal place in the accuracy argument then represents a decimal place in the output.

To illustrate the function at greater depth. If you want an output with one decimal place:

scales::percent(c(1:3/12345, 0.9), accuracy = 0.1)

[1] "0.0%"  "0.0%"  "0.0%"  "90.0%"

while if want it with three decimal places:

scales::percent(c(1:3/12345, 0.9), accuracy = 0.001)

[1] "0.008%"  "0.016%"  "0.024%"  "90.000%"