title: Sklearn can't convert string to float
body: <p>I'm using Sklearn as a machine learning tool, but every time I run my code, it gives this error:</p>
  <pre><code>Traceback (most recent call last):
    File &quot;C:\Users\FakeUserMadeUp\Desktop\Python\Machine Learning\MachineLearning.py&quot;, line 12, in &lt;module&gt;
      model.fit(X_train, Y_train)
    File &quot;C:\Users\FakeUserMadeUp\AppData\Roaming\Python\Python37\site-packages\sklearn\tree\_classes.py&quot;, line 942, in fit
      X_idx_sorted=X_idx_sorted,
    File &quot;C:\Users\FakeUserMadeUp\AppData\Roaming\Python\Python37\site-packages\sklearn\tree\_classes.py&quot;, line 166, in fit
      X, y, validate_separately=(check_X_params, check_y_params)
    File &quot;C:\Users\FakeUserMadeUp\AppData\Roaming\Python\Python37\site-packages\sklearn\base.py&quot;, line 578, in _validate_data
      X = check_array(X, **check_X_params)
    File &quot;C:\Users\FakeUserMadeUp\AppData\Roaming\Python\Python37\site-packages\sklearn\utils\validation.py&quot;, line 746, in check_array
      array = np.asarray(array, order=order, dtype=dtype)
    File &quot;C:\Users\FakeUserMadeUp\AppData\Roaming\Python\Python37\site-packages\pandas\core\generic.py&quot;, line 1993, in __ array __
      return np.asarray(self._values, dtype=dtype)
  ValueError: could not convert string to float: 'Paris'
  </code></pre>
  <p>Here is the code, and down below there's my dataset:</p>
  <p>(I've tried multiple different datasets, also, this dataset is a txt because I made it myself and am to dumb to convert it to csv.)</p>
  <pre><code>    import pandas as pd
      from sklearn.tree import DecisionTreeClassifier as dtc
      from sklearn.model_selection import train_test_split as tts
  
      city_data = pd.read_csv('TimeZoneTable.txt')
      X = city_data.drop(columns=['Country'])
      Y = city_data['Country']
  
      X_train, X_test, Y_train, Y_test = tts(X, Y, test_size = 0.2)
  
      model = dtc()
      model.fit(X_train, Y_train)
      predictions = model.predict(X_test)
  
      print(Y_test)
      print(predictions)
  </code></pre>
  <p>Dataset:</p>
  <pre><code>CityName,Country,Latitude,Longitude,TimeZone
  
  Moscow,Russia,55.45'N,37.37'E,3
  
  Vienna,Austria,48.13'N,16.22'E,2
  
  Barcelona,Spain,41.23'N,2.11'E,2
  
  Madrid,Spain,40.25'N,3.42'W,2
  
  Lisbon,Portugal,38.44'N,9.09'W,1
  
  London,UK,51.30'N,0.08'W,1
  
  Cardiff,UK,51.29'N,3.11'W,1
  
  Edinburgh,UK,55.57'N,3.11'W,1
  
  Dublin,Ireland,53.21'N,6.16'W,1
  
  Paris,France,48.51'N,2.21'E,2
  </code></pre>