value error

[Ben Finney]

Francesco Pietra <chiendarret at gmail.com> writes:

> $ python renumber.py 134-176_rectified.pdb
> Traceback (most recent call last):
>   File "renumber.py", line 6, in <module>
>     L = L[:24] + "%4d" % (int(L[24-28])+133) + L[28:]
> ValueError: invalid literal for int() with base 10: ''

For this reason, it's best to break up big complex expressions like this
into a sequence of simpler statements, so when one of them fails it's
easier to see what went wrong.

In this case, it's because you have L[24-28] where that's almost
certainly not what you mean. It calculates 24-28, getting -4; then uses
that value as an index into L.

You probably wanted to say L[24:28], a slice instead of a single index.

But, really, why are all these magic numbers littering the source,
instead of using named values? You're writing code that will be a
nightmare to maintain.

-- 
 \       “A lot of people are afraid of heights. Not me, I'm afraid of |
  `\                                           widths.” —Steven Wright |
_o__)                                                                  |
Ben Finney