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<== Date ==> <== Thread ==>

Subject: EPICS data extraction with mysql and compressed data
From: Ghribi Adnan <adnan.ghribi@ganil.fr>
To: "tech-talk@aps.anl.gov" <tech-talk@aps.anl.gov>
Date: Tue, 9 Jan 2018 07:37:50 +0000
Dear all,

I have a question regarding recovering data archived by epics using mysql. I use a python code to automatically recover and analyse a set of data. Some of these data are constant and compressed by EPICS so when I extract them with respect to a given data stamp, it gives “nan”. The only way to get value is to have a variation. Looping the time stamps is not feasible as I can easily miss the right time stamp. Do you of of any way that could allow to directly extract constant compressed data ? 

Here is the code I use for the extraction :

def db_fetch1(variable, time1, time2):
    import pymysql
    import numpy as np
    conn = pymysql.connect(host='accmysqlslv', port=3306, user='archive', passwd='archive', db='archive2')
    cur = conn.cursor()
    command = "select float_val from sample s where s.channel_id = (select channel_id from channel where name = '" + variable + "') and smpl_time >= '" + time1 + "' and smpl_time < '"+ time2 + "'"
    cur.execute(command)
    output = []
    for row in cur:
        if np.isreal(row[0]) == True:
            output.append(row[0])
    cur.close()
    conn.close()
    output = np.array(output,dtype=float)
    return output

Thank you,

Best regards,
Adnan Ghribi

 

CNRS - GANIL PhD, Adnan GHRIBI

a: Bvd Henri Becquerel, 14000, Caen, France t: +33 2 31 45 46 80 f: +33 2 31 45 46 47

w: http://www.ganil-spiral2.eu/?set_language=en

 
                                                           

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Re: EPICS data extraction with mysql and compressed data Kasemir, Kay

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