How to add zero before a decimal point for string

[Madu Abuchi]

I have string variables:

.2568
.0356
.025
0.256
0.5682

Please how do I format the first three observations to have zero before the decimal point?

Thanks

[Nick Cox]

Please read and act on FAQ Advice #12 https://www.statalist.org/forums/help#stata

You can't do this by changing the display format.

What you can do is illustrated here

clear 
input str6 whatever 
.2568
.0356
.025
0.256
0.5682
end 

replace whatever = "0" + whatever if substr(whatever, 1, 1) == "." 

list 

     +----------+
     | whatever |
     |----------|
  1. |   0.2568 |
  2. |   0.0356 |
  3. |    0.025 |
  4. |    0.256 |
  5. |   0.5682 |
     +----------+

A more puzzling question is why this kind of data is being held as string any way.

[Danial Hoepfner]

If you want to keep it a string variable, the following will do the trick:

replace myvar="0"+myvar if regexm(myvar,"^\.")

This is a simple regular expression replacement where the ^ tells it to limit the search to the beginning of the string, the \ is to tell it you mean literally a "." since regular expressions interpret that as "any character". Alternatively, if you don't need the numbers as strings (which is likely the case), you can just destring and format the variable to look how you want it.

destring myvar, replace
format myvar %5.3f

You can type in -help format- to see more detail on the options here.

[Clyde Schechter]

Just an addition to #3. Since Madu Abuchi apparently prefers to have a leading zero before the decimal point, the format should be -format myvar %04.3f-.