CODEWITHSUNDEEP
numpypython-3.xmatplotlib
Trico
Trico

Reputation: 41

TypeError when using Matplotlib's strpdate2num with Python 3.2

In my current project I want to read some experimental data from a text file into Python using the following code:

import numpy as np
from matplotlib.dates import strpdate2num

data = np.recfromtxt('example.txt',
                 comments='#',
                 delimiter=';',
                 names=('time', 't_ref', 't_s', 't_amb1', 't_amb2', 't_amb3')
                 ,converters={'time': strpdate2num('"%d.%m.%Y %H:%M:%S"')}
                 )

with example.txt looking like

"04.10.2012 08:15:27";14.4;16;12.78;12.65;12.52
"04.10.2012 08:15:37";14.4;16;12.78;12.65;12.5
"04.10.2012 08:15:47";14.4;16;12.78;12.62;12.5
"04.10.2012 08:15:57";14.4;15.9;12.78;12.65;12.52
...

In Python 2.7, all is well, but when I try to transfer the code in 3.2, I get a TypeError from strpdate2num() saying

TypeError: strptime() argument 0 must be str, not <class 'bytes'>

I am fairly new to Python, but my theory is that NumPy somehow stores the time-array internally as byte instead of string, which collides with the stricter handling of both since Python 3.

Long story short, do you have any idea what might be the cause how to fix that?

Upvotes: 4

Views: 9182

Answers (3)

JGras
JGras

Reputation: 109

The workaround of unutbu work perfectly fine. Meanwhile it seems that the issue has been addressed. Using bytespdate2num() instead of strpdate2num() works for me.

Upvotes: 6

MrRickle
MrRickle

Reputation: 11

I had to remove the quotes from the example text. (using python3.4)

ValueError: time data '"04.10.2012 08:15:27"' does not match format '%d.%m.%Y %H:%M:%S'

Upvotes: 0

unutbu
unutbu

Reputation: 880079

Here is a workaround:

import numpy as np
import matplotlib.dates as mdates

def bytedate2num(fmt):
    def converter(b):
        return mdates.strpdate2num(fmt)(b.decode('ascii'))
    return converter

date_converter = bytedate2num("%d.%m.%Y %H:%M:%S")

data = np.recfromtxt('example.txt',
                     comments='#',
                     delimiter=';',
                     names=('time', 't_ref', 't_s', 't_amb1', 't_amb2', 't_amb3'),
                     converters={'time': date_converter})

Upvotes: 6

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