Check if the wanted file already exists locally before downloading

1 files changed, 15 insertions, 11 deletions

diff --git a/src/python/gudhi/datasets/remote.py b/src/python/gudhi/datasets/remote.py
index fdd20f74..b266467d 100644
--- a/src/python/gudhi/datasets/remote.py
+++ b/src/python/gudhi/datasets/remote.py
@@ -60,20 +60,24 @@ def fetch(url, filename, dirname = "remote_datasets", file_checksum = None):
     file_path: string
         Full path of the created file.
     """
-    if not exists(dirname):
-        makedirs(dirname)
 
     file_path = join(dirname, filename)
 
-    urlretrieve(url, file_path)
-
-    if file_checksum is not None:
-        checksum = _checksum_sha256(file_path)
-        if file_checksum != checksum:
-            raise IOError("{} has a SHA256 checksum : {}, "
-                          "different from expected : {}."
-                          "The file may be corrupted or the given url may be wrong !".format(file_path, checksum,
-                                                      file_checksum))
+    # Check that an existing file does not already exist at file_path
+    if not exists(file_path):
+        # Create directory if not existing
+        if not exists(dirname):
+            makedirs(dirname)
+
+        urlretrieve(url, file_path)
+
+        if file_checksum is not None:
+            checksum = _checksum_sha256(file_path)
+            if file_checksum != checksum:
+                raise IOError("{} has a SHA256 checksum : {}, "
+                            "different from expected : {}."
+                            "The file may be corrupted or the given url may be wrong !".format(file_path, checksum,
+                                                        file_checksum))
 
     return file_path