Reading File from a ZIP Archive on FTP Server without Downloading to Local System

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Reading files directly from an FTP server without downloading them to the local system can be useful in various scenarios, such as when working with large files or when disk space is limited. In this article, we will explore how to read a file from a ZIP archive located on an FTP server using Python and the pandas library.

Introduction

The question at hand involves reading a CSV file stored within a ZIP archive located on an FTP server without downloading the entire ZIP archive to the local system. The solution requires us to use the BytesIO class from the io module, which allows us to create an in-memory binary stream that can be used as if it were a file.

The ftp library is used for interacting with the FTP server, and the zipfile module is used for working with ZIP archives. We will also use the pandas library to read the CSV file.

Prerequisites

To follow along with this article, you will need:

• Python 3.x installed on your system
• The ftp, zipfile, and pandas libraries installed (pip install ftp zipfile pandas)
• An FTP server running on a remote system

Using BytesIO to Read the ZIP Archive

The first step is to establish a connection with the FTP server using the ftp library. We then use the retrbinary method of the ftp object to retrieve the contents of the ZIP archive as a binary stream, which we store in the BytesIO class.

## Establishing an FTP Connection

```python
import ftp
from io import BytesIO

# Establish an FTP connection
ftp_server = 'FTP_SERVER'
username = 'USERNAME'
password = 'PASSWORD'

ftp = ftp.FTP()
ftp.connect(ftp_server)
ftp.login(username, password)

Retrieving the ZIP Archive Contents

Once we have established a connection with the FTP server and logged in, we can use the retrbinary method to retrieve the contents of the ZIP archive as a binary stream.

## Retrieving the ZIP Archive Contents

```python
# Retrieve the ZIP archive contents
ftp.retrbinary('RETR /ParentZipFolder.zip', lambda data: flo.write(data))

# Seek to the beginning of the file
flo.seek(0)

Using ZipFile to Extract Individual Files

Now that we have retrieved the contents of the ZIP archive, we can use the zipfile module to extract individual files. We create a ZipFile object from the BytesIO stream and then open the desired file using its open method.

## Using ZipFile to Extract Individual Files

```python
import zipfile

# Open the ZIP archive as a zip file
with ZipFile(flo) as archive:
    # Open the individual CSV file
    with archive.open('foo/fee/bar.csv') as fd:
        # Read the CSV file into a pandas DataFrame
        df = pd.read_csv(fd)

Example Use Case: Reading a CSV File from an FTP Server

Here is an example use case that demonstrates how to read a CSV file from an FTP server using the BytesIO and zipfile modules:

## Reading a CSV File from an FTP Server

```python
import ftp
from io import BytesIO
import pandas as pd

# Establish an FTP connection
ftp_server = 'FTP_SERVER'
username = 'USERNAME'
password = 'PASSWORD'

ftp = ftp.FTP()
ftp.connect(ftp_server)
ftp.login(username, password)

# Retrieve the ZIP archive contents
flo = BytesIO()
ftp.retrbinary('RETR /ParentZipFolder.zip', lambda data: flo.write(data))

# Seek to the beginning of the file
flo.seek(0)

# Open the ZIP archive as a zip file
with zipfile.ZipFile(flo) as archive:
    # Open the individual CSV file
    with archive.open('foo/fee/bar.csv') as fd:
        # Read the CSV file into a pandas DataFrame
        df = pd.read_csv(fd)

Additional Considerations

When working with files from an FTP server, there are several additional considerations to keep in mind:

• Memory constraints: When reading large files directly from the FTP server, it’s essential to ensure that your system has enough available memory to handle the file. In such cases, you may need to consider alternative approaches, such as streaming or chunking.
• File permissions and access control: Be sure to respect any file permissions or access controls in place on the FTP server to avoid unauthorized access or data breaches.

Conclusion

Reading files directly from an FTP server without downloading them to the local system can be a convenient way to work with large files or when disk space is limited. By using the BytesIO class and the zipfile module, you can extract individual files from a ZIP archive stored on an FTP server.

Last modified on 2023-06-04