#make_kbo_data_file.py
#
#  by Joe Hahn, jhahn@spacescience.org, 21 January 2014.
#
#  Read the input file kbos.txt which contains orbit elements for ~1600 known KBOs.
#  Those data come from the IAU Minor Planet Center, http://www.minorplanetcenter.net/
#  The data that appears in the input file used here (kbos.txt) is cut and pasted from
#  http://www.minorplanetcenter.net/iau/lists/TNOs.html and
#  http://www.minorplanetcenter.net/iau/lists/Centaurs.html

#to execute in ipython:		> ipython --pylab	In [1]: %run make_kbo_data_file.py

#import modules used below
import numpy as np
import pandas as pd
import matplotlib.pyplot as plt 

#read data file...
file = open('kbos.txt','r')
data = np.array(file.readlines())
file.close()
Nlines = data.size

#starting columns for each feature
start_cols = [0, 37, 45, 54, 59, 70, 77, 84, 90, 97, 102, 110, 118, 130, 173]
col_names = ['name', 'q', 'Q', 'H', 'Epoch', 'M', 'Peri', 'Node', 'Incl', 'e', 'a', 
             'Opps', 'Ref', 'NAME', 'Discovery']
Ncols = len(col_names)

#store features in kb dataframe
kb = pd.DataFrame(columns=col_names, index=range(Nlines), dtype=object)
for i in range(Nlines):
    line = data[i]
    for j in range(Ncols):
        start = start_cols[j]
        stop = len(line)
        if (j < Ncols-1): stop = start_cols[j+1]
        val = line[start:stop].strip()
        col = col_names[j]
        kb[col][i] = val

#change column types from string to float
cols = ['q', 'Q', 'M', 'Peri', 'Node', 'Incl', 'e', 'a']
kb[cols] = kb[cols].astype(float)

#save as csv file
kb.to_csv('kbos.csv')