|
| 1 | +# Processing Signals with Pipelines |
| 2 | + |
| 3 | +Now that we have identified and/or generated several primitives for our signal feature generation, we would like to define a reusable *pipeline* for doing so. |
| 4 | + |
| 5 | +First, let's import the required libraries and functions. |
| 6 | + |
| 7 | + |
| 8 | + |
| 9 | +```python |
| 10 | +import sigpro |
| 11 | +import numpy as np |
| 12 | +import pandas as pd |
| 13 | +from matplotlib import pyplot as plt |
| 14 | +from sigpro.demo import _load_demo as get_demo |
| 15 | +``` |
| 16 | + |
| 17 | + |
| 18 | +## Defining Primitives |
| 19 | + |
| 20 | +Recall that we can obtain the list of available primitives with the `get_primitives` method: |
| 21 | + |
| 22 | + |
| 23 | + |
| 24 | +```python |
| 25 | +from sigpro import get_primitives |
| 26 | + |
| 27 | +get_primitives() |
| 28 | +``` |
| 29 | + |
| 30 | + |
| 31 | + |
| 32 | + |
| 33 | + ['sigpro.SigPro', |
| 34 | + 'sigpro.aggregations.amplitude.statistical.crest_factor', |
| 35 | + 'sigpro.aggregations.amplitude.statistical.kurtosis', |
| 36 | + 'sigpro.aggregations.amplitude.statistical.mean', |
| 37 | + 'sigpro.aggregations.amplitude.statistical.rms', |
| 38 | + 'sigpro.aggregations.amplitude.statistical.skew', |
| 39 | + 'sigpro.aggregations.amplitude.statistical.std', |
| 40 | + 'sigpro.aggregations.amplitude.statistical.var', |
| 41 | + 'sigpro.aggregations.frequency.band.band_mean', |
| 42 | + 'sigpro.transformations.amplitude.identity.identity', |
| 43 | + 'sigpro.transformations.amplitude.spectrum.power_spectrum', |
| 44 | + 'sigpro.transformations.frequency.band.frequency_band', |
| 45 | + 'sigpro.transformations.frequency.fft.fft', |
| 46 | + 'sigpro.transformations.frequency.fft.fft_real', |
| 47 | + 'sigpro.transformations.frequency_time.stft.stft', |
| 48 | + 'sigpro.transformations.frequency_time.stft.stft_real'] |
| 49 | + |
| 50 | + |
| 51 | + |
| 52 | +In addition, we can also define our own custom primitives. |
| 53 | + |
| 54 | +## Building a Pipeline |
| 55 | + |
| 56 | +Let’s go ahead and define a feature processing pipeline that sequentially applies the `identity`and `fft` transformations before applying the `std` aggregation. To pass these primitives into the signal processor, we must write each primitive as a dictionary with the following fields: |
| 57 | + |
| 58 | +- `name`: Name of the transformation / aggregation. |
| 59 | +- `primitive`: Name of the primitive to apply. |
| 60 | +- `init_params`: Dictionary containing the initializing parameters for the primitive. * |
| 61 | + |
| 62 | +Since we choose not to specify any initial parameters, we do not set `init_params` in these dictionaries. |
| 63 | + |
| 64 | + |
| 65 | +```python |
| 66 | +identity_transform = {'name': 'identity1', |
| 67 | + 'primitive': 'sigpro.transformations.amplitude.identity.identity'} |
| 68 | + |
| 69 | +fft_transform = {'name': 'fft1', |
| 70 | + 'primitive': 'sigpro.transformations.frequency.fft.fft'} |
| 71 | + |
| 72 | +std_agg = {'name': 'std1', |
| 73 | + 'primitive': "sigpro.aggregations.amplitude.statistical.std"} |
| 74 | +``` |
| 75 | + |
| 76 | + |
| 77 | +We now define a new pipeline containing the primitives we would like to apply. At minimum, we will need to pass in a list of transformations and a list of aggregations; the full list of available arguments is given below. |
| 78 | + |
| 79 | +- Inputs: |
| 80 | + - `transformations (list)` : List of dictionaries containing the transformation primitives. |
| 81 | + - `aggregations (list)`: List of dictionaries containing the aggregation primitives. |
| 82 | + - `values_column_name (str)`(optional):The name of the column that contains the signal values. Defaults to `'values'`. |
| 83 | + - `keep_columns (Union[bool, list])` (optional): Whether to keep non-feature columns in the output DataFrame or not. If a list of column names are passed, those columns are kept. Defaults to `False`. |
| 84 | + - `input_is_dataframe (bool)` (optional): Whether the input is a pandas Dataframe. Defaults to `True`. |
| 85 | + |
| 86 | +Returning to the example: |
| 87 | + |
| 88 | + |
| 89 | +```python |
| 90 | +transformations = [identity_transform, fft_transform] |
| 91 | + |
| 92 | +aggregations = [std_agg] |
| 93 | + |
| 94 | +mypipeline = sigpro.SigPro(transformations, aggregations, values_column_name = 'yvalues', keep_columns = True) |
| 95 | +``` |
| 96 | + |
| 97 | + |
| 98 | +SigPro will proceed to build an `MLPipeline` that can be reused to build features. |
| 99 | + |
| 100 | +To check that `mypipeline` was defined correctly, we can check the input and output arguments with the `get_input_args` and `get_output_args` methods. |
| 101 | + |
| 102 | + |
| 103 | +```python |
| 104 | +input_args = mypipeline.get_input_args() |
| 105 | +output_args = mypipeline.get_output_args() |
| 106 | + |
| 107 | +print(input_args) |
| 108 | +print(output_args) |
| 109 | +``` |
| 110 | + |
| 111 | + [{'name': 'readings', 'keyword': 'data', 'type': 'pandas.DataFrame'}, {'name': 'feature_columns', 'default': None, 'type': 'list'}] |
| 112 | + [{'name': 'readings', 'type': 'pandas.DataFrame'}, {'name': 'feature_columns', 'type': 'list'}] |
| 113 | + |
| 114 | + |
| 115 | +## Applying a Pipeline with `process_signal` |
| 116 | + |
| 117 | +Once our pipeline is correctly defined, we apply the `process_signal` method to a demo dataset. Recall that `process_signal` is defined as follows: |
| 118 | + |
| 119 | + |
| 120 | +```python |
| 121 | +def process_signal(self, data=None, window=None, time_index=None, groupby_index=None, |
| 122 | + feature_columns=None, **kwargs): |
| 123 | + |
| 124 | + ... |
| 125 | + return data, feature_columns |
| 126 | +``` |
| 127 | + |
| 128 | +`process_signal` accepts as input the following arguments: |
| 129 | + |
| 130 | +- `data (pd.Dataframe)` : Dataframe with a column containing signal values. |
| 131 | +- `window (str)`: Duration of window size, e.g. ('1h'). |
| 132 | +- `time_index (str)`: Name of column in `data` that represents the time index. |
| 133 | +- `groupby_index (str or list[str])`: List of column names to group together and take the window over. |
| 134 | +- `feature_columns (list)`: List of columns from the input data that should be considered as features (and not dropped). |
| 135 | + |
| 136 | +`process_signal` outputs the following: |
| 137 | + |
| 138 | +- `data (pd.Dataframe)`: Dataframe containing output feature values as constructed from the signal |
| 139 | +- `feature_columns (list)`: list of (generated) feature names. |
| 140 | + |
| 141 | +We now apply our pipeline to a toy dataset. We define our toy dataset as follows: |
| 142 | + |
| 143 | + |
| 144 | +```python |
| 145 | +demo_dataset = get_demo() |
| 146 | +demo_dataset.columns = ['turbine_id', 'signal_id', 'xvalues', 'yvalues', 'sampling_frequency'] |
| 147 | +demo_dataset.head() |
| 148 | +``` |
| 149 | + |
| 150 | + |
| 151 | + |
| 152 | + |
| 153 | +<div> |
| 154 | + |
| 155 | +<table border="1" class="dataframe"> |
| 156 | + <thead> |
| 157 | + <tr style="text-align: right;"> |
| 158 | + <th></th> |
| 159 | + <th>turbine_id</th> |
| 160 | + <th>signal_id</th> |
| 161 | + <th>xvalues</th> |
| 162 | + <th>yvalues</th> |
| 163 | + <th>sampling_frequency</th> |
| 164 | + </tr> |
| 165 | + </thead> |
| 166 | + <tbody> |
| 167 | + <tr> |
| 168 | + <th>0</th> |
| 169 | + <td>T001</td> |
| 170 | + <td>Sensor1_signal1</td> |
| 171 | + <td>2020-01-01 00:00:00</td> |
| 172 | + <td>[0.43616983763682876, -0.17662312586241055, 0....</td> |
| 173 | + <td>1000</td> |
| 174 | + </tr> |
| 175 | + <tr> |
| 176 | + <th>1</th> |
| 177 | + <td>T001</td> |
| 178 | + <td>Sensor1_signal1</td> |
| 179 | + <td>2020-01-01 01:00:00</td> |
| 180 | + <td>[0.8023828754411122, -0.14122063493312714, -0....</td> |
| 181 | + <td>1000</td> |
| 182 | + </tr> |
| 183 | + <tr> |
| 184 | + <th>2</th> |
| 185 | + <td>T001</td> |
| 186 | + <td>Sensor1_signal1</td> |
| 187 | + <td>2020-01-01 02:00:00</td> |
| 188 | + <td>[-1.3143142430046044, -1.1055740033788437, -0....</td> |
| 189 | + <td>1000</td> |
| 190 | + </tr> |
| 191 | + <tr> |
| 192 | + <th>3</th> |
| 193 | + <td>T001</td> |
| 194 | + <td>Sensor1_signal1</td> |
| 195 | + <td>2020-01-01 03:00:00</td> |
| 196 | + <td>[-0.45981995520032104, -0.3255426061995603, -0...</td> |
| 197 | + <td>1000</td> |
| 198 | + </tr> |
| 199 | + <tr> |
| 200 | + <th>4</th> |
| 201 | + <td>T001</td> |
| 202 | + <td>Sensor1_signal1</td> |
| 203 | + <td>2020-01-01 04:00:00</td> |
| 204 | + <td>[-0.6380405111460377, -0.11924167777027689, 0....</td> |
| 205 | + <td>1000</td> |
| 206 | + </tr> |
| 207 | + </tbody> |
| 208 | +</table> |
| 209 | +</div> |
| 210 | + |
| 211 | + |
| 212 | + |
| 213 | +Finally, we apply the `process_signal` method of our previously defined pipeline: |
| 214 | + |
| 215 | + |
| 216 | +```python |
| 217 | +processed_data, feature_columns = mypipeline.process_signal(demo_dataset, time_index = 'xvalues') |
| 218 | + |
| 219 | +processed_data.head() |
| 220 | + |
| 221 | +``` |
| 222 | + |
| 223 | + |
| 224 | + |
| 225 | + |
| 226 | +<div> |
| 227 | + |
| 228 | +<table border="1" class="dataframe"> |
| 229 | + <thead> |
| 230 | + <tr style="text-align: right;"> |
| 231 | + <th></th> |
| 232 | + <th>turbine_id</th> |
| 233 | + <th>signal_id</th> |
| 234 | + <th>xvalues</th> |
| 235 | + <th>yvalues</th> |
| 236 | + <th>sampling_frequency</th> |
| 237 | + <th>identity1.fft1.std1.std_value</th> |
| 238 | + </tr> |
| 239 | + </thead> |
| 240 | + <tbody> |
| 241 | + <tr> |
| 242 | + <th>0</th> |
| 243 | + <td>T001</td> |
| 244 | + <td>Sensor1_signal1</td> |
| 245 | + <td>2020-01-01 00:00:00</td> |
| 246 | + <td>[0.43616983763682876, -0.17662312586241055, 0....</td> |
| 247 | + <td>1000</td> |
| 248 | + <td>14.444991</td> |
| 249 | + </tr> |
| 250 | + <tr> |
| 251 | + <th>1</th> |
| 252 | + <td>T001</td> |
| 253 | + <td>Sensor1_signal1</td> |
| 254 | + <td>2020-01-01 01:00:00</td> |
| 255 | + <td>[0.8023828754411122, -0.14122063493312714, -0....</td> |
| 256 | + <td>1000</td> |
| 257 | + <td>12.326223</td> |
| 258 | + </tr> |
| 259 | + <tr> |
| 260 | + <th>2</th> |
| 261 | + <td>T001</td> |
| 262 | + <td>Sensor1_signal1</td> |
| 263 | + <td>2020-01-01 02:00:00</td> |
| 264 | + <td>[-1.3143142430046044, -1.1055740033788437, -0....</td> |
| 265 | + <td>1000</td> |
| 266 | + <td>12.051415</td> |
| 267 | + </tr> |
| 268 | + <tr> |
| 269 | + <th>3</th> |
| 270 | + <td>T001</td> |
| 271 | + <td>Sensor1_signal1</td> |
| 272 | + <td>2020-01-01 03:00:00</td> |
| 273 | + <td>[-0.45981995520032104, -0.3255426061995603, -0...</td> |
| 274 | + <td>1000</td> |
| 275 | + <td>10.657243</td> |
| 276 | + </tr> |
| 277 | + <tr> |
| 278 | + <th>4</th> |
| 279 | + <td>T001</td> |
| 280 | + <td>Sensor1_signal1</td> |
| 281 | + <td>2020-01-01 04:00:00</td> |
| 282 | + <td>[-0.6380405111460377, -0.11924167777027689, 0....</td> |
| 283 | + <td>1000</td> |
| 284 | + <td>12.640728</td> |
| 285 | + </tr> |
| 286 | + </tbody> |
| 287 | +</table> |
| 288 | +</div> |
| 289 | + |
| 290 | + |
| 291 | + |
| 292 | + |
| 293 | +Success! We have managed to apply the primitives to generate features on the input dataset. |
| 294 | + |
| 295 | + |
| 296 | + |
| 297 | +```python |
| 298 | + |
| 299 | +``` |
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