README.md: better downsampling code

master
Jörg Thalheim 6 years ago
parent 5bf6236fab
commit 7b93a93e5f
  1. 9
      README.md
  2. 2
      kshape.py

@ -32,9 +32,12 @@ import pandas as pd
# assuming the time series are stored in a tab seperated file, where `time` is
# the name of the column containing the timestamp
df = pd.read_csv(filename, sep="\t", index_col='time', parse_dates=True)
df = df.fillna(method="bfill", limit=1e9)
# drop rows with the same time stamp
df = df.groupby(level=0).first()
# use a meaningful sample size depending on how the frequency of your time series:
# Higher is more accurate, but if series gets too long, the calculation gets cpu and memory intensive.
# Keeping the length below 2000 values is usually a good idea.
df = df.resample("500ms").mean()
df.interpolate(method="time", limit_direction="both", inplace=True)
df.fillna(method="bfill", inplace=True)
```
- kshape also expect no time series with a constant observation value or 'n/a'

@ -7,8 +7,6 @@ from numpy.linalg import norm
from numpy.fft import fft, ifft
#from scipy.linalg import eigh
def zscore(a, axis=0, ddof=0):
a = np.asanyarray(a)
mns = a.mean(axis=axis)

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