Merge remote-tracking branch 'upstream/master' into to_html-to_string

* upstream/master:
  BUG: Casting tz-aware DatetimeIndex to object-dtype ndarray/Index (pandas-dev#23524)
  BUG: Delegate more of Excel parsing to CSV (pandas-dev#23544)
  API: DataFrame.__getitem__ returns Series for sparse column (pandas-dev#23561)
  CLN: use float64_t consistently instead of double, double_t (pandas-dev#23583)
  DOC: Fix Order of parameters in docstrings (pandas-dev#23611)
  TST: Unskip some Categorical Tests (pandas-dev#23613)
  TST: Fix integer ops comparison test (pandas-dev#23619)
  DOC: Fixes to docstring to add validation to CI (pandas-dev#23560)
  DOC: Remove incorrect periods at the end of parameter types (pandas-dev#23600)
  MAINT: tm.assert_raises_regex --> pytest.raises (pandas-dev#23592)
  DOC: Updating Series.resample and DataFrame.resample docstrings (pandas-dev#23197)

ci/code_checks.sh

@@ -151,7 +151,7 @@ if [[ -z "$CHECK" || "$CHECK" == "doctests" ]]; then
 
     MSG='Doctests generic.py' ; echo $MSG
     pytest -q --doctest-modules pandas/core/generic.py \
-        -k"-_set_axis_name -_xs -describe -droplevel -groupby -interpolate -pct_change -pipe -reindex -reindex_axis -resample -to_json -transpose -values -xs"
+        -k"-_set_axis_name -_xs -describe -droplevel -groupby -interpolate -pct_change -pipe -reindex -reindex_axis -to_json -transpose -values -xs"
     RET=$(($RET + $?)) ; echo $MSG "DONE"
 
     MSG='Doctests top-level reshaping functions' ; echo $MSG

doc/source/io.rst

@@ -2861,7 +2861,13 @@ to be parsed.
 
    read_excel('path_to_file.xls', 'Sheet1', usecols=2)
 
-If `usecols` is a list of integers, then it is assumed to be the file column
+You can also specify a comma-delimited set of Excel columns and ranges as a string:
+
+.. code-block:: python
+
+   read_excel('path_to_file.xls', 'Sheet1', usecols='A,C:E')
+
+If ``usecols`` is a list of integers, then it is assumed to be the file column
 indices to be parsed.
 
 .. code-block:: python
@@ -2870,6 +2876,27 @@ indices to be parsed.
 
 Element order is ignored, so ``usecols=[0, 1]`` is the same as ``[1, 0]``.
 
+.. versionadded:: 0.24
+
+If ``usecols`` is a list of strings, it is assumed that each string corresponds
+to a column name provided either by the user in ``names`` or inferred from the
+document header row(s). Those strings define which columns will be parsed:
+
+.. code-block:: python
+
+    read_excel('path_to_file.xls', 'Sheet1', usecols=['foo', 'bar'])
+
+Element order is ignored, so ``usecols=['baz', 'joe']`` is the same as ``['joe', 'baz']``.
+
+.. versionadded:: 0.24
+
+If ``usecols`` is callable, the callable function will be evaluated against
+the column names, returning names where the callable function evaluates to ``True``.
+
+.. code-block:: python
+
+    read_excel('path_to_file.xls', 'Sheet1', usecols=lambda x: x.isalpha())
+
 Parsing Dates
 +++++++++++++
 

doc/source/whatsnew/v0.24.0.txt

@@ -239,6 +239,7 @@ Other Enhancements
 - Added :meth:`Interval.overlaps`, :meth:`IntervalArray.overlaps`, and :meth:`IntervalIndex.overlaps` for determining overlaps between interval-like objects (:issue:`21998`)
 - :func:`~DataFrame.to_parquet` now supports writing a ``DataFrame`` as a directory of parquet files partitioned by a subset of the columns when ``engine = 'pyarrow'`` (:issue:`23283`)
 - :meth:`Timestamp.tz_localize`, :meth:`DatetimeIndex.tz_localize`, and :meth:`Series.tz_localize` have gained the ``nonexistent`` argument for alternative handling of nonexistent times. See :ref:`timeseries.timezone_nonexsistent` (:issue:`8917`)
+- :meth:`read_excel()` now accepts ``usecols`` as a list of column names or callable (:issue:`18273`)
 
 .. _whatsnew_0240.api_breaking:
 
@@ -563,6 +564,7 @@ changes were made:
 - The result of concatenating a mix of sparse and dense Series is a Series with sparse values, rather than a ``SparseSeries``.
 - ``SparseDataFrame.combine`` and ``DataFrame.combine_first`` no longer supports combining a sparse column with a dense column while preserving the sparse subtype. The result will be an object-dtype SparseArray.
 - Setting :attr:`SparseArray.fill_value` to a fill value with a different dtype is now allowed.
+- ``DataFrame[column]`` is now a :class:`Series` with sparse values, rather than a :class:`SparseSeries`, when slicing a single column with sparse values (:issue:`23559`).
 
 Some new warnings are issued for operations that require or are likely to materialize a large dense array:
 
@@ -1128,6 +1130,9 @@ Datetimelike
 - Bug in :class:`PeriodIndex` with attribute ``freq.n`` greater than 1 where adding a :class:`DateOffset` object would return incorrect results (:issue:`23215`)
 - Bug in :class:`Series` that interpreted string indices as lists of characters when setting datetimelike values (:issue:`23451`)
 - Bug in :class:`Timestamp` constructor which would drop the frequency of an input :class:`Timestamp` (:issue:`22311`)
+- Bug in :class:`DatetimeIndex` where calling ``np.array(dtindex, dtype=object)`` would incorrectly return an array of ``long`` objects (:issue:`23524`)
+- Bug in :class:`Index` where passing a timezone-aware :class:`DatetimeIndex` and `dtype=object` would incorrectly raise a ``ValueError`` (:issue:`23524`)
+- Bug in :class:`Index` where calling ``np.array(dtindex, dtype=object)`` on a timezone-naive :class:`DatetimeIndex` would return an array of ``datetime`` objects instead of :class:`Timestamp` objects, potentially losing nanosecond portions of the timestamps (:issue:`23524`)
 
 Timedelta
 ^^^^^^^^^
@@ -1174,6 +1179,7 @@ Offsets
 - Bug in :class:`FY5253` where date offsets could incorrectly raise an ``AssertionError`` in arithmetic operatons (:issue:`14774`)
 - Bug in :class:`DateOffset` where keyword arguments ``week`` and ``milliseconds`` were accepted and ignored.  Passing these will now raise ``ValueError`` (:issue:`19398`)
 - Bug in adding :class:`DateOffset` with :class:`DataFrame` or :class:`PeriodIndex` incorrectly raising ``TypeError`` (:issue:`23215`)
+- Bug in comparing :class:`DateOffset` objects with non-DateOffset objects, particularly strings, raising ``ValueError`` instead of returning ``False`` for equality checks and ``True`` for not-equal checks (:issue:`23524`)
 
 Numeric
 ^^^^^^^
@@ -1301,6 +1307,8 @@ Notice how we now instead output ``np.nan`` itself instead of a stringified form
 - Bug in :meth:`HDFStore.append` when appending a :class:`DataFrame` with an empty string column and ``min_itemsize`` < 8 (:issue:`12242`)
 - Bug in :meth:`read_csv()` in which :class:`MultiIndex` index names were being improperly handled in the cases when they were not provided (:issue:`23484`)
 - Bug in :meth:`read_html()` in which the error message was not displaying the valid flavors when an invalid one was provided (:issue:`23549`)
+- Bug in :meth:`read_excel()` in which ``index_col=None`` was not being respected and parsing index columns anyway (:issue:`20480`)
+- Bug in :meth:`read_excel()` in which ``usecols`` was not being validated for proper column names when passed in as a string (:issue:`20480`)
 
 Plotting
 ^^^^^^^^

pandas/_libs/algos.pxd

@@ -1,9 +1,6 @@
 from util cimport numeric
 
 
-cpdef numeric kth_smallest(numeric[:] a, Py_ssize_t k) nogil
-
-
 cdef inline Py_ssize_t swap(numeric *a, numeric *b) nogil:
     cdef:
         numeric t

pandas/_libs/algos.pyx

@@ -15,8 +15,7 @@ from numpy cimport (ndarray,
                     NPY_FLOAT32, NPY_FLOAT64,
                     NPY_OBJECT,
                     int8_t, int16_t, int32_t, int64_t, uint8_t, uint16_t,
-                    uint32_t, uint64_t, float32_t, float64_t,
-                    double_t)
+                    uint32_t, uint64_t, float32_t, float64_t)
 cnp.import_array()
 
 
@@ -32,10 +31,9 @@ import missing
 
 cdef float64_t FP_ERR = 1e-13
 
-cdef double NaN = <double>np.NaN
-cdef double nan = NaN
+cdef float64_t NaN = <float64_t>np.NaN
 
-cdef int64_t iNaT = get_nat()
+cdef int64_t NPY_NAT = get_nat()
 
 tiebreakers = {
     'average': TIEBREAK_AVERAGE,
@@ -199,7 +197,7 @@ def groupsort_indexer(ndarray[int64_t] index, Py_ssize_t ngroups):
 
 @cython.boundscheck(False)
 @cython.wraparound(False)
-cpdef numeric kth_smallest(numeric[:] a, Py_ssize_t k) nogil:
+def kth_smallest(numeric[:] a, Py_ssize_t k) -> numeric:
     cdef:
         Py_ssize_t i, j, l, m, n = a.shape[0]
         numeric x
@@ -812,23 +810,23 @@ def is_monotonic(ndarray[algos_t, ndim=1] arr, bint timelike):
     n = len(arr)
 
     if n == 1:
-        if arr[0] != arr[0] or (timelike and <int64_t>arr[0] == iNaT):
+        if arr[0] != arr[0] or (timelike and <int64_t>arr[0] == NPY_NAT):
             # single value is NaN
             return False, False, True
         else:
             return True, True, True
     elif n < 2:
         return True, True, True
 
-    if timelike and <int64_t>arr[0] == iNaT:
+    if timelike and <int64_t>arr[0] == NPY_NAT:
         return False, False, True
 
     if algos_t is not object:
         with nogil:
             prev = arr[0]
             for i in range(1, n):
                 cur = arr[i]
-                if timelike and <int64_t>cur == iNaT:
+                if timelike and <int64_t>cur == NPY_NAT:
                     is_monotonic_inc = 0
                     is_monotonic_dec = 0
                     break
@@ -853,7 +851,7 @@ def is_monotonic(ndarray[algos_t, ndim=1] arr, bint timelike):
         prev = arr[0]
         for i in range(1, n):
             cur = arr[i]
-            if timelike and <int64_t>cur == iNaT:
+            if timelike and <int64_t>cur == NPY_NAT:
                 is_monotonic_inc = 0
                 is_monotonic_dec = 0
                 break

pandas/_libs/algos_common_helper.pxi.in

@@ -84,9 +84,9 @@ def put2d_{{name}}_{{dest_name}}(ndarray[{{c_type}}, ndim=2, cast=True] values,
 
 {{endfor}}
 
-#----------------------------------------------------------------------
+# ----------------------------------------------------------------------
 # ensure_dtype
-#----------------------------------------------------------------------
+# ----------------------------------------------------------------------
 
 cdef int PLATFORM_INT = (<ndarray>np.arange(0, dtype=np.intp)).descr.type_num
 

pandas/_libs/algos_rank_helper.pxi.in

@@ -74,9 +74,9 @@ def rank_1d_{{dtype}}(object in_arr, ties_method='average',
     {{elif dtype == 'float64'}}
     mask = np.isnan(values)
     {{elif dtype == 'int64'}}
-    mask = values == iNaT
+    mask = values == NPY_NAT
 
-    # create copy in case of iNaT
+    # create copy in case of NPY_NAT
     # values are mutated inplace
     if mask.any():
         values = values.copy()
@@ -149,7 +149,7 @@ def rank_1d_{{dtype}}(object in_arr, ties_method='average',
             {{if dtype != 'uint64'}}
             isnan = sorted_mask[i]
             if isnan and keep_na:
-                ranks[argsorted[i]] = nan
+                ranks[argsorted[i]] = NaN
                 continue
             {{endif}}
 
@@ -257,7 +257,7 @@ def rank_2d_{{dtype}}(object in_arr, axis=0, ties_method='average',
     {{elif dtype == 'float64'}}
     mask = np.isnan(values)
     {{elif dtype == 'int64'}}
-    mask = values == iNaT
+    mask = values == NPY_NAT
     {{endif}}
 
     np.putmask(values, mask, nan_value)
@@ -317,7 +317,7 @@ def rank_2d_{{dtype}}(object in_arr, axis=0, ties_method='average',
             {{else}}
             if (val == nan_value) and keep_na:
             {{endif}}
-                ranks[i, argsorted[i, j]] = nan
+                ranks[i, argsorted[i, j]] = NaN
 
                 {{if dtype == 'object'}}
                 infs += 1

pandas/_libs/algos_take_helper.pxi.in

@@ -4,9 +4,9 @@ Template for each `dtype` helper function for take
 WARNING: DO NOT edit .pxi FILE directly, .pxi is generated from .pxi.in
 """
 
-#----------------------------------------------------------------------
+# ----------------------------------------------------------------------
 # take_1d, take_2d
-#----------------------------------------------------------------------
+# ----------------------------------------------------------------------
 
 {{py:
 

pandas/_libs/groupby.pyx

@@ -1,14 +1,13 @@
 # -*- coding: utf-8 -*-
 
-cimport cython
-from cython cimport Py_ssize_t
+import cython
+from cython import Py_ssize_t
 
 from libc.stdlib cimport malloc, free
 
 import numpy as np
 cimport numpy as cnp
 from numpy cimport (ndarray,
-                    double_t,
                     int8_t, int16_t, int32_t, int64_t, uint8_t, uint16_t,
                     uint32_t, uint64_t, float32_t, float64_t)
 cnp.import_array()
@@ -20,10 +19,9 @@ from algos cimport (swap, TiebreakEnumType, TIEBREAK_AVERAGE, TIEBREAK_MIN,
                     TIEBREAK_MAX, TIEBREAK_FIRST, TIEBREAK_DENSE)
 from algos import take_2d_axis1_float64_float64, groupsort_indexer, tiebreakers
 
-cdef int64_t iNaT = get_nat()
+cdef int64_t NPY_NAT = get_nat()
 
-cdef double NaN = <double>np.NaN
-cdef double nan = NaN
+cdef float64_t NaN = <float64_t>np.NaN
 
 
 cdef inline float64_t median_linear(float64_t* a, int n) nogil:
@@ -67,13 +65,13 @@ cdef inline float64_t median_linear(float64_t* a, int n) nogil:
     return result
 
 
-# TODO: Is this redundant with algos.kth_smallest?
+# TODO: Is this redundant with algos.kth_smallest
 cdef inline float64_t kth_smallest_c(float64_t* a,
                                      Py_ssize_t k,
                                      Py_ssize_t n) nogil:
     cdef:
         Py_ssize_t i, j, l, m
-        double_t x, t
+        float64_t x, t
 
     l = 0
     m = n - 1
@@ -109,7 +107,7 @@ def group_median_float64(ndarray[float64_t, ndim=2] out,
     cdef:
         Py_ssize_t i, j, N, K, ngroups, size
         ndarray[int64_t] _counts
-        ndarray data
+        ndarray[float64_t, ndim=2] data
         float64_t* ptr
 
     assert min_count == -1, "'min_count' only used in add and prod"
@@ -139,8 +137,8 @@ def group_median_float64(ndarray[float64_t, ndim=2] out,
 @cython.boundscheck(False)
 @cython.wraparound(False)
 def group_cumprod_float64(float64_t[:, :] out,
-                          float64_t[:, :] values,
-                          int64_t[:] labels,
+                          const float64_t[:, :] values,
+                          const int64_t[:] labels,
                           bint is_datetimelike,
                           bint skipna=True):
     """
@@ -177,7 +175,7 @@ def group_cumprod_float64(float64_t[:, :] out,
 @cython.wraparound(False)
 def group_cumsum(numeric[:, :] out,
                  numeric[:, :] values,
-                 int64_t[:] labels,
+                 const int64_t[:] labels,
                  is_datetimelike,
                  bint skipna=True):
     """
@@ -217,7 +215,7 @@ def group_cumsum(numeric[:, :] out,
 
 @cython.boundscheck(False)
 @cython.wraparound(False)
-def group_shift_indexer(ndarray[int64_t] out, ndarray[int64_t] labels,
+def group_shift_indexer(int64_t[:] out, const int64_t[:] labels,
                         int ngroups, int periods):
     cdef:
         Py_ssize_t N, i, j, ii
@@ -291,7 +289,7 @@ def group_fillna_indexer(ndarray[int64_t] out, ndarray[int64_t] labels,
     """
     cdef:
         Py_ssize_t i, N
-        ndarray[int64_t] sorted_labels
+        int64_t[:] sorted_labels
         int64_t idx, curr_fill_idx=-1, filled_vals=0
 
     N = len(out)
@@ -327,10 +325,10 @@ def group_fillna_indexer(ndarray[int64_t] out, ndarray[int64_t] labels,
 
 @cython.boundscheck(False)
 @cython.wraparound(False)
-def group_any_all(ndarray[uint8_t] out,
-                  ndarray[int64_t] labels,
-                  ndarray[uint8_t] values,
-                  ndarray[uint8_t] mask,
+def group_any_all(uint8_t[:] out,
+                  const int64_t[:] labels,
+                  const uint8_t[:] values,
+                  const uint8_t[:] mask,
                   object val_test,
                   bint skipna):
     """Aggregated boolean values to show truthfulness of group elements