Insert a zero between 0 to 9 when iterating with python

Question

I'm writing a code to take a rain time-series and save hourly files for each day in order to feed a hydrological model, so, basically, I need to save each file with the hour of the day with tho digits, like this:

rain_20200101_0000.txt
rain_20200101_0100.txt
...
rain_20200101_0900.txt
rain_20200101_1000.txt
..
rain_20200101_2300.txt

But python doesn't put a zero before numbers between 0-9, so if I use a range(24) to do that it will save the first 10 hours like "rain_20200101_100.txt"

The solution I found was to put an if for x<10 and x>=10 inside the range(24) and insert a "0" before the hour for the first condition, but I think that is too rude and should be a more eficient way to do that. Could you help me with a simpler solution for this code?

Answer 1

Use string formatting to pad with zeros, e.g. "rain_%04d.txt" %(i).

Answer 2

Try this

"123".rjust(4, "0") # 0123

see this treasure on formatting

Answer 3

Simple and sweet

>>> '{:04d}'.format(5)
'0005'