how to convert a txt file to a array python. "could not convert string to float"

Question

I need to import a array value of a txt file but when i print to see my values i get this error: "could not convert string to float: vector(0.1013, 0.2395, 1.1926), vector(0.1276, 0.2361, 1.1760), vector(0.13952644965926353, 0.23617897201269641, 1.1760001652770353), vector(0.16723382973344353, 0.23617897201269641, 1.176000165277035" showing only a few values of the array. Any idea as to what I am doing wrong and what would be the correct way to do it ?

def load_files(self):

    dlg = wx.FileDialog(None,message="Choose File",wildcard= 'Points (*.txt; *.csv)|*.txt;*.csv', defaultFile="",style=wx.FD_OPEN|wx.FD_FILE_MUST_EXIST|wx.FD_CHANGE_DIR)

    if dlg.ShowModal() == wx.ID_CANCEL:
            print ('buh cancelaste')

    else:


        filename=dlg.GetFilename()
        f = open(filename)
        data = f.read()
        data = np.array(data).astype(float)
        print(data)


files = wx.Button(pan, label='Load Coordinates', pos=(x1+158,570), size = (150,40))
files.Bind(wx.EVT_BUTTON, load_files)

txt file.

vector(0.1013, 0.2395, 1.1926), vector(0.1276, 0.2361, 1.1760), vector(0.13952644965926353, 0.23617897201269641, 1.1760001652770353), vector(0.16723382973344353, 0.23617897201269641, 1.1760001652770353), vector(0.18306661834726065, 0.23617897201269641, 1.1760001652770353), vector(0.21077399842144068, 0.23219954535704859, 1.1760001652770353), vector(0.22264858988180353, 0.22822011870140083, 1.1760001652770353), vector(0.23452318134216635, 0.22822011870140083, 1.1760001652770353)

vector(-3.22925576, 0.78085742, 8.2709313 ), vector(0.12270437, 0.29943441, 1.65709467), vector(0.1278586, 0.09019178, 1.24548948), vector(0.25600214, -0.04258577, 0.6109198)

vector(0.12795994, 0.30532043, 1.6896684 ), vector( 0.13624277, 0.09229906, 1.24548948), vector(0.29656594, -0.08827312, 0.69378916), vector (0.19870717, -0.09120946, 1.19266453)

Try using numpy.loadtxt (docs.scipy.org/doc/numpy/reference/generated/numpy.loadtxt.html) - will have to convert the imput file it only contains numbers and commas (if delimiter=','). — user4322779
– user4322779, Commented Aug 21, 2015 at 0:18

hpaulj · Accepted Answer · 2015-08-21 02:54:32Z

The error message indicates that data as passed to np.array is one or more strings of the form

vector(0.1013, 0.2395, 1.1926), vector(0.1276, 0.2361, 1.1760), vector(0.13952644965926353, 0.23617897201269641, 1.1760001652770353), vector(0.16723382973344353, 0.23617897201269641, 1.176000165277035

One long string. You did nothing to break it up on spaces, commas or even newlines.

With astype(float) you are trying to convert that string to a float, or sequence of floats. The Python float(astr) function works with strings like "0.1013", not long ones with many numbers. Even if you broke the data into substrings like

vector(0.1013, 0.2395, 1.1926)

it would have problems, because vector means nothing.

You need to do more parsing of those file lines. You need to split them into lines (e.g. readline()), strip off \n, split them up into blocks like vector(), and further split that into strings with one number each. In other words, a list of strings like this will work:

In [848]: np.array(['0.1013', '0.2395', '1.1926'])
Out[848]: 
array(['0.1013', '0.2395', '1.1926'], 
      dtype='<U6')

In [849]: np.array(['0.1013', '0.2395', '1.1926']).astype(float)
Out[849]: array([ 0.1013,  0.2395,  1.1926])

Observe what happens when data is that 'vector()' string:

In [852]: np.array('vector(0.1013, 0.2395, 1.1926)')
Out[852]: 
array('vector(0.1013, 0.2395, 1.1926)', 
      dtype='<U30')

In [853]: np.array('vector(0.1013, 0.2395, 1.1926)').astype(float)
---------------------------------------------------------------------------
ValueError                                Traceback (most recent call last)
<ipython-input-853-413e30b24430> in <module>()
----> 1 np.array('vector(0.1013, 0.2395, 1.1926)').astype(float)

ValueError: could not convert string to float: 'vector(0.1013, 0.2395, 1.1926)'

astype(float) does not search the string(s) for substrings that look like numbers. Try float('123 45') and variations. float() needs something that looks exactly like a float or integer.

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