statsmodels.tsa.tsatools.add_lag¶
-
statsmodels.tsa.tsatools.
add_lag
(x, col=None, lags=1, drop=False, insert=True)[source]¶ Returns an array with lags included given an array.
- Parameters
- xarray_like
An array or NumPy ndarray subclass. Can be either a 1d or 2d array with observations in columns.
- col‘string’,
int
,or
None
If data is a structured array or a recarray, col can be a string that is the name of the column containing the variable. Or col can be an int of the zero-based column index. If it’s a 1d array col can be None.
- lags
int
The number of lags desired.
- dropbool
Whether to keep the contemporaneous variable for the data.
- insertbool or
int
If True, inserts the lagged values after col. If False, appends the data. If int inserts the lags at int.
- Returns
- array
ndarray
Array with lags
- array
Notes
Trims the array both forward and backward, so that the array returned so that the length of the returned array is len(X) - lags. The lags are returned in increasing order, ie., t-1,t-2,…,t-lags
Examples
>>> import statsmodels.api as sm >>> data = sm.datasets.macrodata.load(as_pandas=False) >>> data = data.data[['year','quarter','realgdp','cpi']] >>> data = sm.tsa.add_lag(data, 'realgdp', lags=2)