Added download from ftp server

pyspedas/__init__.py

@@ -40,6 +40,7 @@
 from .utilities.datasets import find_datasets
 # Note: "download" and "download_file" might be problematic names to import, due to risk of conflict with other packages
 from .utilities.download import download, download_file, check_downloaded_file
+from .utilities.download_ftp import download_ftp
 from .utilities.interpol import interpol
 from .utilities.leap_seconds import load_leap_table
 from .utilities.libs import libs

pyspedas/utilities/download_ftp.py

@@ -0,0 +1,46 @@
+from ftplib import FTP
+import os
+
+
+def download_ftp(
+    ftp_server,
+    ftp_path,
+    filename,
+    local_dir,
+    username="anonymous",
+    password="anonymous@",
+):
+    """
+    Download a file from an FTP server.
+
+    Parameters:
+        ftp_server (str):
+            FTP server address.
+        ftp_path (str):
+            Path on the FTP server where the file is located.
+        filename (str):
+            Name of the file to download.
+        local_dir (str):
+            Local directory to save the file.
+        username (str):
+            Username for the FTP server. Default is 'anonymous'.
+        password (str):
+            Password for the FTP server. Default is 'anonymous@'.
+
+    Returns:
+        list of str:
+            List of files downloaded.
+    """
+    return_files = []
+    with FTP(ftp_server) as ftp:
+        ftp.login(user=username, passwd=password)
+        ftp.cwd(ftp_path)  # Change to the directory containing the file
+
+        local_filename = os.path.join(local_dir, filename)
+        with open(local_filename, "wb") as local_file:
+            ftp.retrbinary("RETR " + filename, local_file.write)
+
+        print(f"File '{filename}' downloaded successfully to '{local_dir}'")
+        return_files.append(local_filename)
+
+    return return_files