f1_col1 f1_col2 f2_col1 f2_col2 ... ...
      0     2.1       0     3.0 ... ...
      1     4.6       1     4.5 ... ...
      2     0.6       2     9.4 ... ...
                      3     5.8 ... ...
                      4     4.6 ... ...

def group_for_display(files_list):

    n = len(files_list)
    X = np.empty(shape=[0, n])

    # loop through all files in the list
    for file_name in files_list:
        # open the file
        with open(file_name) as f:
            # skip first line
            next(f)
            # loop through all lines in the file
            for line in f:
                # split the line into columns
                temp, intens, dummy = line.split(",")
                temp = round(float((temp)))
                intens = float(intens)
                X = np.append(X, [[temp, intens]], axis=0)

    return X

f1_col1 f1_col2
      0     2.1
      1     4.6
      2     0.6
      0     3.0
      1     4.5
      2     9.4
      3     5.8
      4     4.6