Python Pandas, write DataFrame to fixed-width file (to_fwf?)

For custom format for each column you can set format for whole line. fmt param provides formatting for each line

with open('output.dat') as ofile:
     fmt = '%.0f %02.0f %4.1f %3.0f %4.0f %4.1f %4.0f %4.1f %4.0f'
     np.savetxt(ofile, df.values, fmt=fmt)

pandas.DataFrame.to_string() is all you need. The only trick is how to manage the index.

# Write
# df.reset_index(inplace=True)  # uncomment if the index matters
df.to_string(filepath, index=False)

# Read
df = pd.read_fwf(filepath)
# df.set_index(index_names, inplace=True)  # uncomment if the index matters

If the index is a pandas.Index that has no name, reset_index() should assign it to column "index". If it is a pandas.MultiIndex that has no names, it should be assigned to columns ["level_0", "level_1", ...].

Python, Pandas : write content of DataFrame into text File

The question aboves answer helped me. It is not the best, but until to_fwf exists this will do the trick for me...

np.savetxt(r'c:\data\np.txt', df.values, fmt='%d')

or

np.savetxt(r'c:\data\np.txt', df.values, fmt='%10.5f')

Until someone implements this in pandas, you can use the tabulate package:

import pandas as pd
from tabulate import tabulate

def to_fwf(df, fname):
    content = tabulate(df.values.tolist(), list(df.columns), tablefmt="plain")
    open(fname, "w").write(content)

pd.DataFrame.to_fwf = to_fwf