Merge master

Author: makbigc

.github/CONTRIBUTING.md

@@ -2,7 +2,7 @@
 
 Whether you are a novice or experienced software developer, all contributions and suggestions are welcome!
 
-Our main contributing guide can be found [in this repo](https://github.com/pandas-dev/pandas/blob/master/doc/source/development/contributing.rst) or [on the website](https://pandas-docs.github.io/pandas-docs-travis/contributing.html). If you do not want to read it in its entirety, we will summarize the main ways in which you can contribute and point to relevant sections of that document for further information.
+Our main contributing guide can be found [in this repo](https://github.com/pandas-dev/pandas/blob/master/doc/source/development/contributing.rst) or [on the website](https://pandas-docs.github.io/pandas-docs-travis/development/contributing.html). If you do not want to read it in its entirety, we will summarize the main ways in which you can contribute and point to relevant sections of that document for further information.
 
 ## Getting Started
 

.travis.yml

@@ -86,6 +86,14 @@ install:
   - ci/submit_cython_cache.sh
   - echo "install done"
 
+before_script:
+  # display server (for clipboard functionality) needs to be started here,
+  # does not work if done in install:setup_env.sh (GH-26103)
+  - export DISPLAY=":99.0"
+  - echo "sh -e /etc/init.d/xvfb start"
+  - sh -e /etc/init.d/xvfb start
+  - sleep 3
+
 script:
   - echo "script start"
   - source activate pandas-dev

asv_bench/benchmarks/io/csv.py

@@ -3,7 +3,7 @@
 
 import numpy as np
 import pandas.util.testing as tm
-from pandas import DataFrame, Categorical, date_range, read_csv
+from pandas import DataFrame, Categorical, date_range, read_csv, to_datetime
 from pandas.io.parsers import _parser_defaults
 from io import StringIO
 
@@ -96,6 +96,35 @@ def time_read_csv(self, infer_datetime_format, format):
                  infer_datetime_format=infer_datetime_format)
 
 
+class ReadCSVConcatDatetime(StringIORewind):
+
+    iso8601 = '%Y-%m-%d %H:%M:%S'
+
+    def setup(self):
+        rng = date_range('1/1/2000', periods=50000, freq='S')
+        self.StringIO_input = StringIO('\n'.join(
+                                       rng.strftime(self.iso8601).tolist()))
+
+    def time_read_csv(self):
+        read_csv(self.data(self.StringIO_input),
+                 header=None, names=['foo'], parse_dates=['foo'],
+                 infer_datetime_format=False)
+
+
+class ReadCSVConcatDatetimeBadDateValue(StringIORewind):
+
+    params = (['nan', '0', ''],)
+    param_names = ['bad_date_value']
+
+    def setup(self, bad_date_value):
+        self.StringIO_input = StringIO(('%s,\n' % bad_date_value) * 50000)
+
+    def time_read_csv(self, bad_date_value):
+        read_csv(self.data(self.StringIO_input),
+                 header=None, names=['foo', 'bar'], parse_dates=['foo'],
+                 infer_datetime_format=False)
+
+
 class ReadCSVSkipRows(BaseIO):
 
     fname = '__test__.csv'
@@ -273,7 +302,7 @@ def mem_parser_chunks(self):
 
 class ReadCSVParseSpecialDate(StringIORewind):
     params = (['mY', 'mdY', 'hm'],)
-    params_name = ['value']
+    param_names = ['value']
     objects = {
         'mY': '01-2019\n10-2019\n02/2000\n',
         'mdY': '12/02/2010\n',
@@ -290,4 +319,29 @@ def time_read_special_date(self, value):
                  names=['Date'], parse_dates=['Date'])
 
 
+class ParseDateComparison(StringIORewind):
+    params = ([False, True],)
+    param_names = ['cache_dates']
+
+    def setup(self, cache_dates):
+        count_elem = 10000
+        data = '12-02-2010\n' * count_elem
+        self.StringIO_input = StringIO(data)
+
+    def time_read_csv_dayfirst(self, cache_dates):
+        read_csv(self.data(self.StringIO_input), sep=',', header=None,
+                 names=['Date'], parse_dates=['Date'], cache_dates=cache_dates,
+                 dayfirst=True)
+
+    def time_to_datetime_dayfirst(self, cache_dates):
+        df = read_csv(self.data(self.StringIO_input),
+                      dtype={'date': str}, names=['date'])
+        to_datetime(df['date'], cache=cache_dates, dayfirst=True)
+
+    def time_to_datetime_format_DD_MM_YYYY(self, cache_dates):
+        df = read_csv(self.data(self.StringIO_input),
+                      dtype={'date': str}, names=['date'])
+        to_datetime(df['date'], cache=cache_dates, format='%d-%m-%Y')
+
+
 from ..pandas_vb_common import setup  # noqa: F401

asv_bench/benchmarks/io/parsers.py

@@ -0,0 +1,34 @@
+import numpy as np
+
+from pandas._libs.tslibs.parsing import (
+    _concat_date_cols, _does_string_look_like_datetime)
+
+
+class DoesStringLookLikeDatetime(object):
+
+    params = (['2Q2005', '0.0', '10000'],)
+    param_names = ['value']
+
+    def setup(self, value):
+        self.objects = [value] * 1000000
+
+    def time_check_datetimes(self, value):
+        for obj in self.objects:
+            _does_string_look_like_datetime(obj)
+
+
+class ConcatDateCols(object):
+
+    params = ([1234567890, 'AAAA'], [1, 2])
+    param_names = ['value', 'dim']
+
+    def setup(self, value, dim):
+        count_elem = 10000
+        if dim == 1:
+            self.object = (np.array([value] * count_elem),)
+        if dim == 2:
+            self.object = (np.array([value] * count_elem),
+                           np.array([value] * count_elem))
+
+    def time_check_concat(self, value, dim):
+        _concat_date_cols(self.object)

ci/azure/windows.yml

@@ -17,16 +17,15 @@ jobs:
         CONDA_PY: "37"
 
   steps:
-    - task: CondaEnvironment@1
-      inputs:
-        updateConda: no
-        packageSpecs: ''
-
-    - script: |
-        ci\\incremental\\setup_conda_environment.cmd
-      displayName: 'Before Install'
+    - powershell: Write-Host "##vso[task.prependpath]$env:CONDA\Scripts"
+      displayName: Add conda to PATH
+    - script: conda update -q -n base conda
+      displayName: Update conda
+    - script: conda env create -q --file ci\\deps\\azure-windows-$(CONDA_PY).yaml
+      displayName: Create anaconda environment
     - script: |
         call activate pandas-dev
+        call conda list
         ci\\incremental\\build.cmd
       displayName: 'Build'
     - script: |

ci/code_checks.sh

@@ -169,15 +169,6 @@ if [[ -z "$CHECK" || "$CHECK" == "patterns" ]]; then
     invgrep -r -E --include '*.py' '(unittest(\.| import )mock|mock\.Mock\(\)|mock\.patch)' pandas/tests/
     RET=$(($RET + $?)) ; echo $MSG "DONE"
 
-    # Check that we use pytest.raises only as a context manager
-    #
-    # For any flake8-compliant code, the only way this regex gets
-    # matched is if there is no "with" statement preceding "pytest.raises"
-    MSG='Check for pytest.raises as context manager (a line starting with `pytest.raises` is invalid, needs a `with` to precede it)' ; echo $MSG
-    MSG='TODO: This check is currently skipped because so many files fail this. Please enable when all are corrected (xref gh-24332)' ; echo $MSG
-    # invgrep -R --include '*.py' -E '[[:space:]] pytest.raises' pandas/tests
-    # RET=$(($RET + $?)) ; echo $MSG "DONE"
-
     MSG='Check for wrong space after code-block directive and before colon (".. code-block ::" instead of ".. code-block::")' ; echo $MSG
     invgrep -R --include="*.rst" ".. code-block ::" doc/source
     RET=$(($RET + $?)) ; echo $MSG "DONE"
@@ -239,6 +230,10 @@ if [[ -z "$CHECK" || "$CHECK" == "doctests" ]]; then
     pytest -q --doctest-modules pandas/core/groupby/groupby.py -k"-cumcount -describe -pipe"
     RET=$(($RET + $?)) ; echo $MSG "DONE"
 
+    MSG='Doctests datetimes.py' ; echo $MSG
+    pytest -q --doctest-modules pandas/core/tools/datetimes.py
+    RET=$(($RET + $?)) ; echo $MSG "DONE"
+
     MSG='Doctests top-level reshaping functions' ; echo $MSG
     pytest -q --doctest-modules \
         pandas/core/reshape/concat.py \

ci/incremental/setup_conda_environment.cmd

@@ -118,16 +118,10 @@ echo "conda list"
 conda list
 
 # Install DB for Linux
-export DISPLAY=":99."
 if [ ${TRAVIS_OS_NAME} == "linux" ]; then
   echo "installing dbs"
   mysql -e 'create database pandas_nosetest;'
   psql -c 'create database pandas_nosetest;' -U postgres
-
-  echo
-  echo "sh -e /etc/init.d/xvfb start"
-  sh -e /etc/init.d/xvfb start
-  sleep 3
 else
    echo "not using dbs on non-linux"
 fi

ci/run_with_env.cmd

@@ -285,6 +285,11 @@ provides a familiar ``DataFrame`` interface for out-of-core, parallel and distri
 
 Dask-ML enables parallel and distributed machine learning using Dask alongside existing machine learning libraries like Scikit-Learn, XGBoost, and TensorFlow.
 
+`Koalas <https://koalas.readthedocs.io/en/latest/>`__
+~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
+
+Koalas provides a familiar pandas DataFrame interface on top of Apache Spark. It enables users to leverage multi-cores on one machine or a cluster of machines to speed up or scale their DataFrame code.
+
 `Odo <http://odo.pydata.org>`__
 ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~