def _f2s(v):
    """convert float to string without scientific notation"""
    s, sep, e = str(v).partition('e')
    a, sep, b = s.partition('.')
    pos = len(a) + int(e or 0)
    s = (a + b).rstrip('0')
    if pos >= len(s):
        return s.ljust(pos, '0')
    elif pos <= 0:
        return '0.' + '0' * -pos + s
    else:
        return s[:pos] + '.' + s[pos:]
