pythonnumpygenfromtxt

Loading a date in Numpy genfromtxt

I'm trying to import a simple CSV file with Numpy genfromtxt but can't manage to convert the data of first column to dates.

Here is my code:

import numpy as np
from datetime import datetime

str2date = lambda x: datetime.strptime(x, '%Y-%m-%d %H:%M:%S')

data = np.genfromtxt('C:\\\\data.csv',dtype=None,names=True, delimiter=',', converters = {0: str2date})

I get the following error in str2date:

TypeError: must be str, not bytes

The problem is there are many columns, so I'd prefer avoiding the specification of all the column types (which are basically numerical).

Solution

  • The problem is that the argument passed to str2date is of this form b'%Y-%m-%d %H:%M:%S'. These are bytes, which rightfully cannot be parsed to a datetime object. The solution to that problem is quite simple though, as you should decode your byte string to a UTF-8 string:

    str2date = lambda x: datetime.strptime(x.decode("utf-8"), '%Y-%m-%d %H:%M:%S')