Comparing Data

After getting bokeh to graph data I started trying to compare years/months against each other eg June 2019 vs 2018 but this did not quite go to plan especially as i had forgotten that despite dragelec running for almost 5yrs the SQL recording only started in Aug 2018…

There is another issue; the way the data is recorded; i store values everytime a signal is output from one of the sensors this means when interrogating the data i can have a different number of values per day so a straight forward export of data does not work.

For example the following SQL select statement

for row in curs.execute("SELECT * FROM home_mon WHERE DATE>(?) and DATE<(?)", ('2018-12-01', '2018-12-25')):

counts 6547 rows for December 2018 whilst the same for 2019 only counts 6516 this discrepancy is larger for some other months. So to compare periods i wrote the following to get one value per hour

for row in curs.execute("SELECT * FROM home_mon WHERE DATE>(?)", (yr18,)):
    dat = dt.datetime.fromtimestamp(int(float(row[1]))).strftime('%Y-%m-%d %H:%M:%S')
    hr =  dt.datetime.fromtimestamp(int(float(row[1]))).strftime('%H:')
    if dat > "2018-12-01" and dat < "2018-12-25":
        if hr != pasthr18:
            pasthr18 = hr
            data_18.append(row[4])
    if dat > "2019-12-01" and dat < "2019-12-25":
        if hr != pasthr19:
            pasthr19 = hr
            data_19.append(row[4])

    cnt = cnt + 1
    x.append(cnt)

The result of this is for the periods 01-12 > 25-12 I get 576 values for both years meaning a real comparison can now be done.

So using bokeh to graph the period we get;

and the same in excel but tweaked to show date axis;

a bit of further exploration gives;

Finally the average temperatures for the period 01st-25th December 2018 vs 2019

This year would appear to provide a warm start for the next with an almost 12degC rise from the 17th to 19th of December and as i’m writing this [2019-12-30 Mon 14:57] the grass is green, the sun is shining, it’s 7.4degC outside but if i ignore the lack of leaves on the trees it looks like a late summers evening.