7 4 NaN 5 11 6 13 dtype: float64 • Added a DataFrame.round method to round the values to a variable number of decimal places (GH10568). In [49]: df = pd.DataFrame(np.random.random([3, 3]), columns=['A' Regression Results ============================================================================== Dep. Variable: hr No. Observations: 68 Model: Poisson Df Residuals: 63 Method: MLE Df Model: 4 Date: Fri, 09 value input. (GH9054) • Allow timedelta string conversion when leading zero is missing from time definition, ie 0:00:00 vs 00:00:00. (GH9570) 1.3. v0.16.1 (May 11, 2015) 37 pandas: powerful Python data

value_labels . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1118 pandas.io.stata.StataReader.variable_labels . . . . . . . . . . . . . . . . . . . . . . . . . . . 1118 pandas.io.stata.StataWriter.write_file 09:00:03 3.0 2013-01-01 09:00:05 NaN 2013-01-01 09:00:06 NaN Using the time-specification generates variable windows for this sparse data. In [20]: dft.rolling('2s').sum() Out[20]: B foo 2013-01-01 09:00:00 append now supports the ignore_index option (GH13677) • .to_stata() and StataWriter can now write variable labels to Stata dta files using a dictionary to make column names to labels (GH13535, GH13536)

value_labels . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1121 pandas.io.stata.StataReader.variable_labels . . . . . . . . . . . . . . . . . . . . . . . . . . . 1121 pandas.io.stata.StataWriter.write_file 09:00:03 3.0 2013-01-01 09:00:05 NaN 2013-01-01 09:00:06 NaN Using the time-specification generates variable windows for this sparse data. In [20]: dft.rolling('2s').sum() Out[20]: B foo 2013-01-01 09:00:00 append now supports the ignore_index option (GH13677) • .to_stata() and StataWriter can now write variable labels to Stata dta files using a dictionary to make column names to labels (GH13535, GH13536)

value_labels . . . . . . . . . . . . . . . . . . . . . . . 1258 34.1.13.5 pandas.io.stata.StataReader.variable_labels . . . . . . . . . . . . . . . . . . . . . . 1258 34.1.13.6 pandas.io.stata.StataWriter.write_file packages’ test suites. Use @pytest.mark.slow instead, which achieves the same thing (GH16850) • Moved definition of MergeError to the pandas.errors module. • The signature of Series.set_axis() and DataFrame The .groupby(..).agg(..), .rolling(..).agg(..), and .resample(..).agg(..) syntax can ac- cept a variable of inputs, including scalars, list, and a dict of column names to scalars or lists. This provides

value_labels . . . . . . . . . . . . . . . . . . . . . . . 1219 34.1.12.5 pandas.io.stata.StataReader.variable_labels . . . . . . . . . . . . . . . . . . . . . . 1219 34.1.12.6 pandas.io.stata.StataWriter.write_file The .groupby(..).agg(..), .rolling(..).agg(..), and .resample(..).agg(..) syntax can ac- cept a variable of inputs, including scalars, list, and a dict of column names to scalars or lists. This provides 09:00:03 3.0 2013-01-01 09:00:05 NaN 2013-01-01 09:00:06 NaN Using the time-specification generates variable windows for this sparse data. In [20]: dft.rolling('2s').sum() Out[20]: B foo 2013-01-01 09:00:00

subplots=True may draw unnecessary minor xticks and yticks (GH7801) • Bug in StataReader which did not read variable labels in 117 files due to difference between Stata docu- mentation and implementation (GH7816) month/quarter/year defined by the frequency of the DateTimeIndex / Timestamp (GH4565, GH6998) • Local variable usage has changed in pandas.eval()/DataFrame.eval()/DataFrame.query() (GH5987). For the DataFrame locals – Local variables must be referred to explicitly. This means that even if you have a local variable that is not a column you must still refer to it with the ’@’ prefix. – You can have an expression

subplots=True may draw unnecessary minor xticks and yticks (GH7801) • Bug in StataReader which did not read variable labels in 117 files due to difference between Stata docu- mentation and implementation (GH7816) month/quarter/year defined by the frequency of the DateTimeIndex / Timestamp (GH4565, GH6998) • Local variable usage has changed in pandas.eval()/DataFrame.eval()/DataFrame.query() (GH5987). For the DataFrame locals – Local variables must be referred to explicitly. This means that even if you have a local variable that is not a column you must still refer to it with the ’@’ prefix. – You can have an expression

value_labels . . . . . . . . . . . . . . . . . . . . . . . 1217 34.1.12.5 pandas.io.stata.StataReader.variable_labels . . . . . . . . . . . . . . . . . . . . . . 1217 34.1.12.6 pandas.io.stata.StataWriter.write_file The .groupby(..).agg(..), .rolling(..).agg(..), and .resample(..).agg(..) syntax can ac- cept a variable of inputs, including scalars, list, and a dict of column names to scalars or lists. This provides 09:00:03 3.0 2013-01-01 09:00:05 NaN 2013-01-01 09:00:06 NaN Using the time-specification generates variable windows for this sparse data. In [20]: dft.rolling('2s').sum() Out[20]: B foo 2013-01-01 09:00:00

where ValueError is wrongly raised when calling count() method of a SeriesGroupBy when the grouping variable only contains NaNs and numpy version < 1.13 (GH21956). • Multiple bugs in pandas.core.window.Rolling Regression Results ============================================================================== Dep. Variable: hr R-squared: 0.685 Model: OLS Adj. R-squared: 0.665 Method: Least Squares F-statistic: 34.28 DataFrame column attribute access and IPython completion If a DataFrame column label is a valid Python variable name, the column can be accessed like an attribute: In [121]: df = pd.DataFrame({'foo1': np.random

Rolling.max() and pandas.core.window.Rolling.min() where incorrect results are returned with an empty variable window (GH26005) • Raise a helpful exception when an unsupported weighted window function is used Regression Results ============================================================================== Dep. Variable: hr R-squared: 0.685 Model: OLS Adj. R-squared: 0.665 Method: Least Squares F-statistic: 34.28 DataFrame column attribute access and IPython completion If a DataFrame column label is a valid Python variable name, the column can be accessed like an attribute: In [131]: df = pd.DataFrame({'foo1': np.random