hdfs: Allow hdfs read/write for files

Now the following will work:

If hdfs3 is not installed, Throws:
  ImportError: The hdfs3 library is required to handle hdfs files

If hdfs3 is installed but libhdfs3 is not installed, Throws:
  ImportError: Can not find the shared library: libhdfs3.so

If hdfs3 is installed it works for the code:
  pd.read_csv("hdfs://localhost:9000/tmp/a.csv")

If hdfs3 is installed and HADOOP_CONF_DIR is set, it works for the code:
  HADOOP_CONF_DIR=/usr/local/Cellar/hadoop/2.7.0/libexec/etc/hadoop/
  pd.read_csv("hdfs:///tmp/a.csv")

Author: AbdealiLoKo

doc/source/io.rst

@@ -78,7 +78,7 @@ Basic
 
 filepath_or_buffer : various
   Either a path to a file (a :class:`python:str`, :class:`python:pathlib.Path`,
-  or :class:`py:py._path.local.LocalPath`), URL (including http, ftp, and S3
+  or :class:`py:py._path.local.LocalPath`), URL (including http, ftp, hdfs, and S3
   locations), or any object with a ``read()`` method (such as an open file or
   :class:`~python:io.StringIO`).
 sep : str, defaults to ``','`` for :func:`read_csv`, ``\t`` for :func:`read_table`
@@ -1579,6 +1579,12 @@ You can pass in a URL to a CSV file:
    df = pd.read_csv('https://download.bls.gov/pub/time.series/cu/cu.item',
                     sep='\t')
 
+Or a hdfs URL:
+
+.. code-block:: python
+
+   df = pd.read_csv('hdfs://<nodenamehost>:<nodenameport>/pandas-test/tips.csv')
+
 S3 URLs are handled as well:
 
 .. code-block:: python
@@ -1849,7 +1855,7 @@ The parser will try to parse a ``DataFrame`` if ``typ`` is not supplied or
 is ``None``. To explicitly force ``Series`` parsing, pass ``typ=series``
 
 - ``filepath_or_buffer`` : a **VALID** JSON string or file handle / StringIO. The string could be
-  a URL. Valid URL schemes include http, ftp, S3, and file. For file URLs, a host
+  a URL. Valid URL schemes include http, ftp, hdfs, S3, and file. For file URLs, a host
   is expected. For instance, a local file could be
   file ://localhost/path/to/table.json
 - ``typ``    : type of object to recover (series or frame), default 'frame'

doc/source/whatsnew/v0.22.0.txt

@@ -139,6 +139,7 @@ Other Enhancements
 - :func:`read_excel()` has gained the ``nrows`` parameter (:issue:`16645`)
 - :func:``DataFrame.to_json`` and ``Series.to_json`` now accept an ``index`` argument which allows the user to exclude the index from the JSON output (:issue:`17394`)
 - ``IntervalIndex.to_tuples()`` has gained the ``na_tuple`` parameter to control whether NA is returned as a tuple of NA, or NA itself (:issue:`18756`)
+- :func:`read_csv` now supports reading from hdfs by giving "hdfs:///tmp/data.csv". The hadoop configs will try to be automatically found. The configs can also be mentioned using the format "hdfs://<nodenamehost>:<nodenameport>/tmp/data.csv"
 
 .. _whatsnew_0220.api_breaking:
 

pandas/compat/__init__.py

@@ -44,7 +44,7 @@
 PY36 = (sys.version_info >= (3, 6))
 PYPY = (platform.python_implementation() == 'PyPy')
 
-try:
+try:  # Python 2 imports
     import __builtin__ as builtins
     # not writeable when instantiated with string, doesn't handle unicode well
     from cStringIO import StringIO as cStringIO
@@ -53,12 +53,14 @@
     BytesIO = StringIO
     import cPickle
     import httplib
-except ImportError:
+    from urlparse import urlparse as parse_url
+except ImportError:  # Equivalent Python 3 imports
     import builtins
     from io import StringIO, BytesIO
     cStringIO = StringIO
     import pickle as cPickle
     import http.client as httplib
+    from urllib.parse import urlparse as parse_url
 
 from pandas.compat.chainmap import DeepChainMap
 

pandas/io/common.py

@@ -99,6 +99,14 @@ def _is_s3_url(url):
         return False
 
 
+def _is_hdfs_url(url):
+    """Check for an hdfs url"""
+    try:
+        return parse_url(url).scheme == 'hdfs'
+    except:
+        return False
+
+
 def _expand_user(filepath_or_buffer):
     """Return the argument with an initial component of ~ or ~user
        replaced by that user's home directory.
@@ -201,6 +209,12 @@ def get_filepath_or_buffer(filepath_or_buffer, encoding=None,
                                          encoding=encoding,
                                          compression=compression)
 
+    if _is_hdfs_url(filepath_or_buffer):
+        from pandas.io import hdfs
+        return hdfs.get_filepath_or_buffer(filepath_or_buffer,
+                                           encoding=encoding,
+                                           compression=compression)
+
     if isinstance(filepath_or_buffer, (compat.string_types,
                                        compat.binary_type,
                                        mmap.mmap)):
@@ -314,12 +328,19 @@ def _get_handle(path_or_buf, mode, encoding=None, compression=None,
     handles : list of file-like objects
         A list of file-like object that were openned in this function.
     """
+    need_text_wrapping = [BytesIO]
     try:
         from s3fs import S3File
-        need_text_wrapping = (BytesIO, S3File)
+        need_text_wrapping.append(S3File)
+    except ImportError:
+        pass
+    try:
+        from hdfs3 import HDFile
+        need_text_wrapping.append(HDFile)
     except ImportError:
-        need_text_wrapping = (BytesIO,)
+        pass
 
+    need_text_wrapping = tuple(need_text_wrapping)
     handles = list()
     f = path_or_buf
 

pandas/io/hdfs.py

@@ -0,0 +1,22 @@
+""" s3 support for remote file interactivity """
+from pandas import compat
+try:
+    import hdfs3
+except:
+    raise ImportError("The hdfs3 library is required to handle hdfs files")
+
+
+def get_filepath_or_buffer(filepath_or_buffer, encoding=None,
+                           compression=None):
+    parsed_url = compat.parse_url(filepath_or_buffer)
+    if ":" in parsed_url.netloc:
+        host, port = parsed_url.netloc.rsplit(":", 1)
+        try:
+            port = int(port)
+            fs = hdfs3.HDFileSystem(host=host, port=port)
+        except ValueError:
+            pass
+    else:
+        fs = hdfs3.HDFileSystem()
+    filepath_or_buffer = fs.open(parsed_url.path)
+    return filepath_or_buffer, None, compression

pandas/io/s3.py

@@ -6,15 +6,10 @@
 except:
     raise ImportError("The s3fs library is required to handle s3 files")
 
-if compat.PY3:
-    from urllib.parse import urlparse as parse_url
-else:
-    from urlparse import urlparse as parse_url
-
 
 def _strip_schema(url):
     """Returns the url without the s3:// part"""
-    result = parse_url(url)
+    result = compat.parse_url(url)
     return result.netloc + result.path
 
 

pandas/tests/io/test_hdfs.py

@@ -0,0 +1,8 @@
+from pandas.io.common import _is_hdfs_url
+
+
+class TestHDFSURL(object):
+
+    def test_is_hdfs_url(self):
+        assert _is_hdfs_url("hdfs://pandas/somethingelse.com")
+        assert not _is_hdfs_url("hdf://pandas/somethingelse.com")