title: raise IOError("%s not found." % path)
body: <p>In the past week, I spent my time trying to solve a big problem when compiling my program.py. My program script is:</p>
  <pre><code>import numpy
  import matplotlib
  import matplotlib.pyplot as plt
  import scipy.interpolate
  from matplotlib.font_manager import FontProperties
  import matplotlib.cm as cm
  from mpl_toolkits.axes_grid1.axes_divider import make_axes_locatable
  import os
  #import pathlib
  #from pathlib import Path
  
  
  font = FontProperties()
  font.set_family('serif')
  font.set_name('Times New Roman')
  font.set_style('italic')
  marker_size = .5
  font_size = 20.
  
  font_size_labels = 50
  font_weight = 'bold'
  
  # Generate data:
  file_path = r'C:\Users\annyc\Desktop\gap.txt' #the 'r' preceding the string turns off the eight-character Unicode escape (for a raw string) which was failing.
  #file_name = os.path.basename(file_path)
  x, y, z, center = numpy.loadtxt(file_path, dtype='float64', delimiter='\t', unpack=True)
  
  # Set up a regular grid of interpolation points
  xi, yi = numpy.linspace(x.min(), x.max(), 500), numpy.linspace(y.min(), y.max(), 500)
  xi, yi = numpy.meshgrid(xi, yi)
  
  fig = plt.figure(figsize=(10,15))
  ax1 = fig.add_subplot()
  
  for axis in ['top','bottom','left','right']:
      ax1.spines[axis].set_linewidth(3)
  
  # Interpolate
  zi = scipy.interpolate.griddata((x, y), z, (xi, yi), method='linear')
  
  ax2 = fig.add_subplot()
  
  im = plt.imshow(zi, vmin=0., vmax=1, origin='lower', aspect = &quot;auto&quot;, cmap='hot',
             extent=[x.min(), x.max(), y.min(), y.max()])
  ax2_divider = make_axes_locatable(ax2)
  
  plt.xlabel('R', fontproperties=font, fontsize=font_size)
  plt.xticks(size=15)
  plt.tick_params(width=3, length=10)
  plt.ylabel(r'$\delta$', fontproperties=font, fontsize=font_size)
  plt.yticks(size=15)
  #plt.title('(a)', fontproperties=font, fontsize=font_size, pad=0.5)
  
  #plt.scatter(x, y, c=z)
  
  levels = [0.2, 0.3, 0.4, 0.5, 0.6, 0.7, 0.8]
  manual_locations = [(2.5, 10), (1, 10), (2, 60), (1.5, 70), (1, 70), (0.75, 80), (2.5, 40), (2, 60)]
  
  
  
  contour = plt.contour(xi, yi, zi, colors='green', linestyles='dashdot', linewidths = 2)
  plt.clabel(contour, colors = 'green', fmt = '%2.1f', fontsize=15, manual=manual_locations)
  
  #cbar = plt.colorbar(im, ticks=[0, 0.1, 0.2, 0.3, 0.4, 0.5, 0.6, 0.7], shrink=1., aspect=20.,
  #                    orientation='horizontal', pad = 0.25)
  
  cax2 = ax2_divider.append_axes(&quot;top&quot;, size=.3, pad=0.75)
  cbar2 = fig.colorbar(im, cax=cax2, ticks=[0, 0.1, 0.2, 0.3, 0.4, 0.5, 0.6, 0.7, 0.8, 0.9, 1],
                      orientation='horizontal')
  cbar2.set_label('Bandgap Width', fontproperties=font, fontsize=font_size)
  cbar2.ax.tick_params(labelsize=17, width=3, direction='in', length=10)
  cbar2.outline.set_edgecolor('black')
  cbar2.outline.set_linewidth(3)
  
  #plt.savefig('gap_r_delta.pdf')
  plt.savefig('gap_r_delta.png', dpi=600)
  plt.show()
  </code></pre>
  <p>and the error that insists on appearing when I compile this program is:</p>
  <pre><code>Traceback (most recent call last):
    File &quot;C: \ Users \ annyc \ Desktop \ data \ 3d_contour.py&quot;, line 24, in &lt;module&gt;
      x, y, z, center = numpy.loadtxt (file_path, dtype = 'float64', delimiter = '\ t', unpack = True)
    File &quot;C: \ Users \ annyc \ AppData \ Local \ Programs \ Python \ Python37 \ lib \ site-packages \ numpy \ lib \ npyio.py&quot;, line 961, in loadtxt
      fh = np.lib._datasource.open (fname, 'rt', encoding = encoding)
    File &quot;C: \ Users \ annyc \ AppData \ Local \ Programs \ Python \ Python37 \ lib \ site-packages \ numpy \ lib \ _datasource.py&quot;, line 195, in open
      return ds.open (path, mode, encoding = encoding, newline = newline)
    File &quot;C: \ Users \ annyc \ AppData \ Local \ Programs \ Python \ Python37 \ lib \ site-packages \ numpy \ lib \ _datasource.py&quot;, line 535, in open
      raise IOError (&quot;% s not found.&quot;% path)
  OSError: C: \ Users \ annyc \ Desktop \ gap.txt not found.
  </code></pre>
  <p>I don't know how to solve this problem since the gap.txt file is in the same folder as the program.py.</p>
  <p>Could someone tell me what I did wrong? Thanks!</p>