Converting seconds in date form Numpy Python

Question

The delta_s function calculates the difference of time between 2 dates in the dates with seconds. Then the average median and max values for the differences is calculated. I am trying to convert the times in seconds for average median and max values but it does not work. i want to convert it in the form of x days x hours x minutes x seconds.

Code:

import numpy as np

dates= np.array(['2017-09-15 07:11:00' ,'2017-09-15 11:25:30', '2017-09-15 12:11:10', '2021-04-07 22:43:12', '2021-04-08 00:49:18'], 
                dtype="datetime64[ns]")

delta_s = np.diff(dates) // 1e9 # nanoseconds to seconds
delta_s = delta_s.astype(np.float64)

delta_avg = np.average(delta_s)
delta_median= np.median(delta_s)
delta_max = np.max(delta_s)
delta_max_index= np.argmax(delta_s)

what specifically "does not work"?

FObersteiner
– FObersteiner

2021-05-29 08:44:41 +00:00
Commented May 29, 2021 at 8:44 — FObersteiner
– FObersteiner, Commented May 29, 2021 at 8:44

Akshay · Accepted Answer · 2021-05-29 03:26:00Z

1

The line delta_s = np.diff(dates) // 1e9 does not actually convert nanoseconds to seconds. It simply divides 1e9 to the timedelta object but the time unit is preserved timedelta64[ns].

>>> np.diff(dates)
array([    15270000000000,      2740000000000, 112357922000000000,
            7566000000000], dtype='timedelta64[ns]')
>>> np.diff(dates) // 1e9
array([    15270,      2740, 112357922,      7566],
      dtype='timedelta64[ns]')

This may mess up with any calculations you're doing.

Use

delta_s = np.array([np.timedelta64(td, 's') for td in np.diff(dates) ])

Currently there are no inbuilt functions to format timedelta to strings. However you can use something of this sort.

# Function to convert seconds to Human readable Timedelta string
def seconds_to_tdstring(total_seconds):
    days, remainder = divmod(total_seconds, 60 * 60 * 24)
    hours, remainder = divmod(remainder, 60 * 60)
    minutes, seconds = divmod(remainder, 60)
    return '{:02} Days {:02} Hours {:02} Minutes {:02} Seconds'.format(int(days), int(hours), int(minutes), int(seconds))

print(seconds_to_tdstring(delta_avg))  

Output:
325 Days 04 Hours 24 Minutes 34 Seconds

I have modified the answer from a similar question .

answered May 29, 2021 at 3:26

Akshay

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1 Comment

FObersteiner Over a year ago

the list comprehension is not needed; you can simply do delta_s = np.diff(dates).astype('timedelta64[s]')

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