## Pandas - Rolling slope calculation

How to calculate slope of each columns' rolling(window=60) value, stepped by 5?

I'd like to calculate every 5 minutes' value, and I don't need every record's results.

Here's sample dataframe and results:

df Time A ... N 2016-01-01 00:00 1.2 ... 4.2 2016-01-01 00:01 1.2 ... 4.0 2016-01-01 00:02 1.2 ... 4.5 2016-01-01 00:03 1.5 ... 4.2 2016-01-01 00:04 1.1 ... 4.6 2016-01-01 00:05 1.6 ... 4.1 2016-01-01 00:06 1.7 ... 4.3 2016-01-01 00:07 1.8 ... 4.5 2016-01-01 00:08 1.1 ... 4.1 2016-01-01 00:09 1.5 ... 4.1 2016-01-01 00:10 1.6 ... 4.1 .... result Time A ... N 2016-01-01 00:04 xxx ... xxx 2016-01-01 00:09 xxx ... xxx 2016-01-01 00:14 xxx ... xxx ...

Can df.rolling function be applied to this problem?

It's fine if NaN is in the window, meaning subset could be less than 60.

try this

windows = df.groupby("Time")["A"].rolling(60) df[out] = windows.apply(lambda x: np.polyfit(range(60), x, 1)[0], raw=True).values

**pandas.DataFrame.rolling — pandas 1.1.1 documentation,** Provide rolling window calculations. Parameters. windowint, offset, or BaseIndexer subclass. Size of the moving window. This is the number of observations� Python is a great language for doing data analysis, primarily because of the fantastic ecosystem of data-centric python packages. Pandas is one of those packages and makes importing and analyzing data much easier. Pandas dataframe.rolling () function provides the feature of rolling window calculations. The concept of rolling window calculation is most primarily used in signal processing and time series data.

It seems that what you want is rolling with **a specific step size**.
However, according to the documentation of pandas, step size is currently **not supported** in `rolling`

.

If the data size is not too large, just perform rolling on all data and select the results using indexing.

Here's a sample dataset. For simplicity, the time column is represented using integers.

data = pd.DataFrame(np.random.rand(500, 1) * 10, columns=['a'])

a 0 8.714074 1 0.985467 2 9.101299 3 4.598044 4 4.193559 .. ... 495 9.736984 496 2.447377 497 5.209420 498 2.698441 499 3.438271

Then, roll and calculate slopes,

def calc_slope(x): slope = np.polyfit(range(len(x)), x, 1)[0] return slope # set min_periods=2 to allow subsets less than 60. # use [4::5] to select the results you need. result = data.rolling(60, min_periods=2).apply(calc_slope)[4::5]

The result will be,

a 4 -0.542845 9 0.084953 14 0.155297 19 -0.048813 24 -0.011947 .. ... 479 -0.004792 484 -0.003714 489 0.022448 494 0.037301 499 0.027189

Or, you can refer to this post. The first answer provides a numpy way to achieve this: step size in pandas.DataFrame.rolling

**Python,** rolling() function provides the feature of rolling window calculations. The concept of rolling window calculation is most primarily used in signal� pandas.DataFrame.rolling¶ DataFrame.rolling (window, min_periods = None, center = False, win_type = None, on = None, axis = 0, closed = None) [source] ¶ Provide rolling window calculations. Parameters window int, offset, or BaseIndexer subclass. Size of the moving window. This is the number of observations used for calculating the statistic.

You could use pandas Resample. Note that to use this , you need an index with time value

df.index = pd.to_datetime(df.Time) print df result = df.resample('5Min').bfill() print result Time A N Time 2016-01-01 00:00:00 2016-01-01 00:00 1.2 4.2 2016-01-01 00:01:00 2016-01-01 00:01 1.2 4.0 2016-01-01 00:02:00 2016-01-01 00:02 1.2 4.5 2016-01-01 00:03:00 2016-01-01 00:03 1.5 4.2 2016-01-01 00:04:00 2016-01-01 00:04 1.1 4.6 2016-01-01 00:05:00 2016-01-01 00:05 1.6 4.1 2016-01-01 00:06:00 2016-01-01 00:06 1.7 4.3 2016-01-01 00:07:00 2016-01-01 00:07 1.8 4.5 2016-01-01 00:08:00 2016-01-01 00:08 1.1 4.1 2016-01-01 00:09:00 2016-01-01 00:09 1.5 4.1 2016-01-01 00:10:00 2016-01-01 00:10 1.6 4.1 2016-01-01 00:15:00 2016-01-01 00:15 1.6 4.1 Time A N

Output

Time 2016-01-01 00:00:00 2016-01-01 00:00 1.2 4.2 2016-01-01 00:05:00 2016-01-01 00:05 1.6 4.1 2016-01-01 00:10:00 2016-01-01 00:10 1.6 4.1 2016-01-01 00:15:00 2016-01-01 00:15 1.6 4.1

**Calculating rolling regression coefficients of a DataFrame,** I'm not sure if Quantopian supports pandas rolling regression? I have no idea what this error means. Any insight would be appreciated! pandas.core.window.rolling.Rolling.std¶ Rolling.std (ddof = 1, * args, ** kwargs) [source] ¶ Calculate rolling standard deviation. Normalized by N-1 by default. This can be changed using the ddof argument.

hi sorry to pull this old question up. but I cannot follow the results :S

def calc_slope(x): slope = np.polyfit(range(len(x)), x, 1)[0] return slope # set min_periods=2 to allow subsets less than 60. # use [4::5] to select the results you need. data['slope'] = data.rolling(3, min_periods=3).apply(calc_slope) print(data.to_string())

with a result of:

a slope 0 6.902663 NaN 1 2.257267 NaN 2 0.172393 -3.365135 3 9.642700 3.692717 4 1.221879 0.524743 5 1.634674 -4.004013 6 8.274599 3.526360 7 9.800035 4.082681 8 4.577713 -1.848443 9 1.368656 -4.215690 10 9.377983 2.400135 11 9.795934 4.213639 12 3.045406 -3.166288 13 6.063934 -1.866000 14 8.202430 2.578512

any ideas?

thx

**How to get slope from timeseries data in pandas?,** Pandas rolling slope, I'm trying to rolling apply a custom function to a pandas dataframe. Windows identify sub periods of your time series ○ Calculate metrics for� For a sanity check, let's also use the pandas in-built rolling function and see if it matches with our custom python based simple moving average. df['pandas_SMA_3'] = df.iloc[:,1].rolling(window=3).mean() df.head()

I would like to calculate the slope using scipy.stats.linregress for each entity a and b in the above example. I tried using groupby on the first column, following the split-apply-combine advice , but it seems problematic since it's expecting one Series of values ( a and b ), whereas I need to operate on the two columns on the right.

calculating slope for a series trendline in Pandas. Ask Question Asked 4 years, 1 month ago. Pandas conditional creation of a series/dataframe column.

pandas.DataFrame.pct_change¶ DataFrame.pct_change (periods = 1, fill_method = 'pad', limit = None, freq = None, ** kwargs) [source] ¶ Percentage change between the current and a prior element.

##### Comments

- Thanks, but what I want for output is the slope value of last five records. Time stamp starts with 00:00, so 00:04 is the first row of the output. (1-> 00:00, 2-> 00:01, 3-> 00:02, 4-> 00:03, 5-> 00:04)