pandas-cobol-io 0.1.0

Pandas extension for COBOL-style fixed-width files handling multibyte encoding.

pandas-cobol-io

Pandas extension for COBOL-style fixed-width files (FWF).

Installation

pip install pandas-cobol-io

Usage

To import df.to_fwf and pd.parse_fwf

import pandas as pd
import pandas_cobol_io

When user imports pandas_cobol_io, these two functions are added to pandas objects.

df.to_fwf (DataFrame -> Fixed Width Format Text)

to_fwf method is added to DataFrame.

df = pd.DataFrame({
    "ID": [1, 20],
    "NAME": ["A", "B"],
})

# Metadata: List of (Type, Length)
# "9": Zero padding (Right aligned)
# "X": Space padding (Left aligned)

metadata = [
    ("9", 5),
    ("X", 10),
]

# Convert to fixed-width strings
lines = df.to_fwf(metadata, enc="cp932")

# Save to file
with open("output.txt", "w", encoding="cp932") as f:
    f.writelines(lines)
# output.txt
# 00001A         # <- White spaces exist here.
# 00020B         # <-
# 123456789111111
#          012345

pd.parse_fwf (Fixed Width Format Text -> DataFrame)

parse_fwf function is added to pd.

params = {
    "ID": 5,
    "NAME": 10,
}
result = pd.parse_fwf("output.txt", params, enc="cp932")
df, errors, lines = (result[x] for x in ("df", "errors", "lines"))

print(df)
#       ID        NAME
# 0  00001  A         
# 1  00020  B         

miscellaneous

from pprint import pprint

from pandas_cobol_io import Fwf, fwf_row

fwf = Fwf(enc := "cp932")

# header
header_info = {
    "data-distinction": (1, "9", 2),
    "dummy": (" ", "X", 13),
}
fwf.header = fwf_row(header_info, enc)

# contents
df = pd.DataFrame({
    "ID": [1, 20],
    "NAME": ["A", "B"],
})
metadata = [
    ("9", 5),
    ("X", 10),
]
fwf.contents = df.to_fwf(metadata, enc)

# footer
tracker_info = {
    "data-distinction": (9, "9", 2),
    "dummy": (" ", "X", 13),
}
end_info = {
    "dummy": ("EOF", "X", 15),
}
fwf.footer = [fwf_row(x, enc) for x in (tracker_info, end_info)]

pprint(fwf)
pprint(fwf.data)
# Fwf(encoding='cp932',
#     header=['01             \n'],
#     contents=['00001A         \n', '00020B         \n'],
#     footer=[['09             \n'], ['EOF            \n']])
# ['01             \n',
#  '00001A         \n',
#  '00020B         \n',
#  '09             \n',
#  'EOF            \n']

License

MIT License