i2cdetect-style hexdump in Python

hexdump.py

def hexdump(data=None, col_width=16):
    #This function follows the i2cdump output format, as it's the most readable out there
    if data is None: data = d
    # character conversion function
    conv = lambda x: chr(x) if x in range(0x20, 0x7f) else '.'
    # getting row count
    row_count = ceil(len(data)/col_width)
    max_row_num_len_hex = len(hex(row_count)[2:])
    # first line - header
    hex_digits = [hex(i)[2:] for i in range(16)]
    hex_cols = "  ".join(hex_digits)
    ascii_cols = "".join(hex_digits)
    print("{}  {}\t {}".format(" "*(max_row_num_len_hex+1), hex_cols, ascii_cols))
    # next lines: actual data
    for r in range(row_count):
        line = data[r*col_width:][:col_width]
        line_num_hex = hex(r*col_width)[2:].zfill(max_row_num_len_hex)
        # if c TODO insert "row ends" check here
        hex_values = " ".join((hex(b)[2:].zfill(2) for b in line))
        ascii_values = "".join(conv(b) for b in line)
        # in last row, if there are not enough elements to fill the row, we'll need spaces
        lacking_elements = col_width-len(line)
        spaces = " "*3*lacking_elements
        print("{}: {}{}\t {}".format(line_num_hex, hex_values, spaces, ascii_values))