Increase Sampling rate on time-series data with Pandas











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I have accelerometer data with variable sampling rate. I am trying to increase it a constant sampling rate 50hz through interpolation.The problem with the timestamps is, it doesn't have milliseconds.
enter image description here



How do i do it without losing the data i already have?










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    I have accelerometer data with variable sampling rate. I am trying to increase it a constant sampling rate 50hz through interpolation.The problem with the timestamps is, it doesn't have milliseconds.
    enter image description here



    How do i do it without losing the data i already have?










    share|improve this question
























      up vote
      0
      down vote

      favorite









      up vote
      0
      down vote

      favorite











      I have accelerometer data with variable sampling rate. I am trying to increase it a constant sampling rate 50hz through interpolation.The problem with the timestamps is, it doesn't have milliseconds.
      enter image description here



      How do i do it without losing the data i already have?










      share|improve this question













      I have accelerometer data with variable sampling rate. I am trying to increase it a constant sampling rate 50hz through interpolation.The problem with the timestamps is, it doesn't have milliseconds.
      enter image description here



      How do i do it without losing the data i already have?







      python pandas






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      share|improve this question










      asked Nov 19 at 16:01









      subhash

      76110




      76110
























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          You can first set the index as your datetime column using df.set_index('timestamp') and use df.resample(). The directive you want to pass into the resample function is L for milliseconds, but you can read more here. The resample function also lets you choose a number of interpolation modes.






          share|improve this answer





















          • I tried this df.resample('20ms', on='timestamp'). This only take first occurence's value and increases the sampling rate but all the rest of data for that particular second is lost. Its just populated as nan.
            – subhash
            Nov 19 at 16:10






          • 1




            I see. That's tricky because to pandas, it just sees a bunch of values with the same timestamp and doesn't know what to do with it. Moreover, it doesn't even seem that there are always the same number of repeated timestamps. It seems you may have roll something manually; basically go second by second, assume all values for a given second are spaced out evenly for a second, and interpolate using the mean of neighbors or something.
            – rvd
            Nov 19 at 16:14










          • Another possible way is to go through second by second and change the timestamps so that they are spaced evenly by for how many times a second value repeats, and then use resample to fill everything else. This way pandas will still do most of the work.
            – rvd
            Nov 19 at 16:15











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          up vote
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          down vote













          You can first set the index as your datetime column using df.set_index('timestamp') and use df.resample(). The directive you want to pass into the resample function is L for milliseconds, but you can read more here. The resample function also lets you choose a number of interpolation modes.






          share|improve this answer





















          • I tried this df.resample('20ms', on='timestamp'). This only take first occurence's value and increases the sampling rate but all the rest of data for that particular second is lost. Its just populated as nan.
            – subhash
            Nov 19 at 16:10






          • 1




            I see. That's tricky because to pandas, it just sees a bunch of values with the same timestamp and doesn't know what to do with it. Moreover, it doesn't even seem that there are always the same number of repeated timestamps. It seems you may have roll something manually; basically go second by second, assume all values for a given second are spaced out evenly for a second, and interpolate using the mean of neighbors or something.
            – rvd
            Nov 19 at 16:14










          • Another possible way is to go through second by second and change the timestamps so that they are spaced evenly by for how many times a second value repeats, and then use resample to fill everything else. This way pandas will still do most of the work.
            – rvd
            Nov 19 at 16:15















          up vote
          0
          down vote













          You can first set the index as your datetime column using df.set_index('timestamp') and use df.resample(). The directive you want to pass into the resample function is L for milliseconds, but you can read more here. The resample function also lets you choose a number of interpolation modes.






          share|improve this answer





















          • I tried this df.resample('20ms', on='timestamp'). This only take first occurence's value and increases the sampling rate but all the rest of data for that particular second is lost. Its just populated as nan.
            – subhash
            Nov 19 at 16:10






          • 1




            I see. That's tricky because to pandas, it just sees a bunch of values with the same timestamp and doesn't know what to do with it. Moreover, it doesn't even seem that there are always the same number of repeated timestamps. It seems you may have roll something manually; basically go second by second, assume all values for a given second are spaced out evenly for a second, and interpolate using the mean of neighbors or something.
            – rvd
            Nov 19 at 16:14










          • Another possible way is to go through second by second and change the timestamps so that they are spaced evenly by for how many times a second value repeats, and then use resample to fill everything else. This way pandas will still do most of the work.
            – rvd
            Nov 19 at 16:15













          up vote
          0
          down vote










          up vote
          0
          down vote









          You can first set the index as your datetime column using df.set_index('timestamp') and use df.resample(). The directive you want to pass into the resample function is L for milliseconds, but you can read more here. The resample function also lets you choose a number of interpolation modes.






          share|improve this answer












          You can first set the index as your datetime column using df.set_index('timestamp') and use df.resample(). The directive you want to pass into the resample function is L for milliseconds, but you can read more here. The resample function also lets you choose a number of interpolation modes.







          share|improve this answer












          share|improve this answer



          share|improve this answer










          answered Nov 19 at 16:07









          rvd

          43117




          43117












          • I tried this df.resample('20ms', on='timestamp'). This only take first occurence's value and increases the sampling rate but all the rest of data for that particular second is lost. Its just populated as nan.
            – subhash
            Nov 19 at 16:10






          • 1




            I see. That's tricky because to pandas, it just sees a bunch of values with the same timestamp and doesn't know what to do with it. Moreover, it doesn't even seem that there are always the same number of repeated timestamps. It seems you may have roll something manually; basically go second by second, assume all values for a given second are spaced out evenly for a second, and interpolate using the mean of neighbors or something.
            – rvd
            Nov 19 at 16:14










          • Another possible way is to go through second by second and change the timestamps so that they are spaced evenly by for how many times a second value repeats, and then use resample to fill everything else. This way pandas will still do most of the work.
            – rvd
            Nov 19 at 16:15


















          • I tried this df.resample('20ms', on='timestamp'). This only take first occurence's value and increases the sampling rate but all the rest of data for that particular second is lost. Its just populated as nan.
            – subhash
            Nov 19 at 16:10






          • 1




            I see. That's tricky because to pandas, it just sees a bunch of values with the same timestamp and doesn't know what to do with it. Moreover, it doesn't even seem that there are always the same number of repeated timestamps. It seems you may have roll something manually; basically go second by second, assume all values for a given second are spaced out evenly for a second, and interpolate using the mean of neighbors or something.
            – rvd
            Nov 19 at 16:14










          • Another possible way is to go through second by second and change the timestamps so that they are spaced evenly by for how many times a second value repeats, and then use resample to fill everything else. This way pandas will still do most of the work.
            – rvd
            Nov 19 at 16:15
















          I tried this df.resample('20ms', on='timestamp'). This only take first occurence's value and increases the sampling rate but all the rest of data for that particular second is lost. Its just populated as nan.
          – subhash
          Nov 19 at 16:10




          I tried this df.resample('20ms', on='timestamp'). This only take first occurence's value and increases the sampling rate but all the rest of data for that particular second is lost. Its just populated as nan.
          – subhash
          Nov 19 at 16:10




          1




          1




          I see. That's tricky because to pandas, it just sees a bunch of values with the same timestamp and doesn't know what to do with it. Moreover, it doesn't even seem that there are always the same number of repeated timestamps. It seems you may have roll something manually; basically go second by second, assume all values for a given second are spaced out evenly for a second, and interpolate using the mean of neighbors or something.
          – rvd
          Nov 19 at 16:14




          I see. That's tricky because to pandas, it just sees a bunch of values with the same timestamp and doesn't know what to do with it. Moreover, it doesn't even seem that there are always the same number of repeated timestamps. It seems you may have roll something manually; basically go second by second, assume all values for a given second are spaced out evenly for a second, and interpolate using the mean of neighbors or something.
          – rvd
          Nov 19 at 16:14












          Another possible way is to go through second by second and change the timestamps so that they are spaced evenly by for how many times a second value repeats, and then use resample to fill everything else. This way pandas will still do most of the work.
          – rvd
          Nov 19 at 16:15




          Another possible way is to go through second by second and change the timestamps so that they are spaced evenly by for how many times a second value repeats, and then use resample to fill everything else. This way pandas will still do most of the work.
          – rvd
          Nov 19 at 16:15


















           

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