Can someone help me understand this bit of string formatting?

I was trying a coding challenge and gave up, in the submitted answers for others I found this string formatting method.

number = 10
for i in range(1, number+1):
        print("{0:{w}d} {0:{w}o} {0:{w}X} {0:{w}b}".format(i, w=len("{0:b}".format(number))))

The output was:

   1    1    1    1
   2    2    2   10
   3    3    3   11
   4    4    4  100
   5    5    5  101
   6    6    6  110
   7    7    7  111
   8   10    8 1000
   9   11    9 1001
  10   12    A 1010

It is correct for the question I just had a few questions. Like for example where did the spaces come from? How do the d,o,X,b format it as int, oct, hex, bin? What is the 0: for? What is that i in the first format doing

So I tried this:

i = 8
    print("{0:6b}".format(i))

The output was:

  1000

with 2 spaces at the front. The i here is what is getting turned into binary. The spaces seem to work like
6 - len(str(bin(i)) then the binary value.

Any help explaining or a link to a Youtube video would be greatly appreciated.

This is a nested format() implementation:

You can break your code and check:

This w thing is just 4

number = 10
for i in range(1, number+1):
    print(len("{0:b}".format(number)))

#output
4
4
4
4
4
4
4
4
4
4

You can get rid of this by directly using 4:

number = 10
for i in range(1, number+1):
        print("{0:4d} {0:4o} {0:4X} {0:4b}".format(i))

#output

   1    1    1    1
   2    2    2   10
   3    3    3   11
   4    4    4  100
   5    5    5  101
   6    6    6  110
   7    7    7  111
   8   10    8 1000
   9   11    9 1001
  10   12    A 1010

4 is used for padding; if you do not use 4 the this will be output:

number = 10
for i in range(1, number+1):
        print("{0:d} {0:o} {0:X} {0:b}".format(i))

1 1 1 1
2 2 2 10
3 3 3 11
4 4 4 100
5 5 5 101
6 6 6 110
7 7 7 111
8 10 8 1000
9 11 9 1001
10 12 A 1010

Please go through the format() documentation for detailed explanation:

https://docs.python.org/3/library/string.html#string.Formatter.format

Here is the snip from the doc: