def long_file(data_file, dataformat, sample_list, savedir=None, srm_id=None, **autorange_args):
    """
    TODO: Check for existing files in savedir, don't overwrite?
    """
    if isinstance(sample_list, str):
        if os.path.exists(sample_list):
            sample_list = np.genfromtxt(sample_list, dtype=str)
        else:
            raise ValueError('File {} not found.')
    elif not isinstance(sample_list, (list, np.ndarray)):
        raise ValueError('sample_list should be an array_like or a file.')
        
    if srm_id is not None:
        srm_replace = []
        for s in sample_list:
            if srm_id in s:
                s = srm_id
            srm_replace.append(s)
        sample_list = srm_replace
                
    _, _, dat, meta = read_data(data_file, dataformat=dataformat, name_mode='file')
    
    if 'date' in meta:
        d = dateutil.parser.parse(meta['date'])
    else:
        d = datetime.datetime.now()
    # autorange
    bkg, sig, trn, _ = autorange(dat['Time'], dat['total_counts'], **autorange_args)
    
    ns = np.zeros(sig.size)
    ns[sig] = np.cumsum((sig ^ np.roll(sig, 1)) & sig)[sig]
    
    n = int(max(ns))
    
    if len(sample_list) != n:
        warn('Length of sample list does not match number of ablations in file.\n' + 
             'We will continue, but please make sure the assignments are correct.')
    
    # calculate split boundaries
    bounds = []
    lower = 0
    sn = 0
    next_sample = ''
    for ni in range(n-1):
        sample = sample_list[sn]
        next_sample = sample_list[sn + 1]
                
        if sample != next_sample:
            current_end = np.argwhere(dat['Time'] == dat['Time'][ns == ni + 1].max())[0]
            next_start = np.argwhere(dat['Time'] == dat['Time'][ns == ni + 2].min())[0]
            upper = (current_end + next_start) // 2

            bounds.append((sample, (int(lower), int(upper))))

            lower = upper + 1

        sn += 1

    bounds.append((sample_list[-1], (int(upper) + 1, len(ns))))

    # split up data
    sections = {}
    seen = {}
    for s, (lo, hi) in bounds:
        if s not in seen:
            seen[s] = 0
        else:
            seen[s] += 1
            s += '_{}'.format(seen[s])
        sections[s] = {'oTime': dat['Time'][lo:hi]}
        sections[s]['Time'] = sections[s]['oTime'] - np.nanmin(sections[s]['oTime'])
        sections[s]['rawdata'] = {}
        for k, v in dat['rawdata'].items():
            sections[s]['rawdata'][k] = v[lo:hi]
        sections[s]['starttime'] = d + datetime.timedelta(seconds=np.nanmin(sections[s]['oTime']))
    
    # save output
    if savedir is None:
        savedir = os.path.join(os.path.dirname(os.path.abspath(data_file)), os.path.splitext(os.path.basename(data_file))[0] + '_split')
    if not os.path.isdir(savedir):
        os.makedirs(savedir)
    
    header = ['# Long data file split by latools on {}'.format(datetime.datetime.now().strftime('%Y:%m:%d %H:%M:%S'))]
    if 'date' not in meta:
        header.append('# Warning: No date specified in file - Analysis Times are date file was split. ')
    else:
        header.append('# ')
        header.append('# ')
        header.append('# ')
    
    flist = [savedir]
    for s, dat in sections.items():
        iheader = header.copy()
        iheader.append('# Sample: {}'.format(s))
        iheader.append('# Analysis Time: {}'.format(dat['starttime'].strftime('%Y-%m-%d %H:%M:%S')))
    
        iheader = '\n'.join(iheader) + '\n'
        
        out = pd.DataFrame({analyte_2_namemass(k): v for k, v in dat['rawdata'].items()}, index=dat['Time'])
        out.index.name = 'Time'
        csv = out.to_csv()
        
        with open('{}/{}.csv'.format(savedir, s), 'w') as f:
            f.write(iheader)
            f.write(csv)
        flist.append('   {}.csv'.format(s))
    
    print("File split into {} sections.\n Saved to: {}\n\n Import using the 'REPRODUCE' configuration.".format(n, '\n'.join(flist)))
    return None
TODO: Check for existing files in savedir, don't overwrite?