title: ValueError: could not convert string to float, Python
body: <p>I have a dataframe on which i'm trying to implement feature selection. 
  There are 45 columns of types, integer, float and object. </p>
  
  <p>But I'm unable to fit any feature selection model since its throwing vale Error. Please help me out </p>
  
  <p>Dataframe :</p>
  
  <pre><code>member_id   loan_amnt   funded_amnt funded_amnt_inv term        batch_enrolled   int_rate   grade
  58189336    14350       14350       14350           36 months                    19.19      E
  70011223    4800        4800        4800            36 months   BAT1586599       10.99      B
  
   sub_grade  emp_title   emp_length  home_ownership  annual_inc  verification_status pymnt_plan  desc                purpose title      zip_code addr_state   dti
   E3         clerk       9 years     OWN             28700       Source Verified     n           debt_consolidation  Debt consolidation 349xx    FL        33.88
   B4         HR          &lt; 1 year    MORTGAGE        65000       Source Verified     n           home_improvement    Home improvement    209xx   MD      3.64
  
   last_week_pay  loan_status
   44th week          0
   9th week           1
  </code></pre>
  
  <p>Code:</p>
  
  <pre><code> import numpy
   from pandas import read_csv
   from sklearn.decomposition import PCA
   # load data
   df = pd.read_csv("C:/Users/anagha/Documents/Python  Scripts/train_indessa.csv")
   array = df.values
   X = array[:,0:44]
   Y = array[:,44]
   # feature extraction
   pca = PCA(n_components=3)
   fit = pca.fit(X)
  </code></pre>
  
  <p>Error:</p>
  
  <pre><code> Traceback (most recent call last):
  
   File "&lt;ipython-input-8-20f3863fd66e&gt;", line 2, in &lt;module&gt;
   fit = pca.fit(X)
  
   File "C:\Users\anagha\Anaconda3\lib\site-  packages\sklearn\decomposition\pca.py", line 301, in fit
  self._fit(X)
  
  File "C:\Users\anagha\Anaconda3\lib\site-packages\sklearn\decomposition\pca.py", line 333, in _fit
  copy=self.copy)
  
  File "C:\Users\anagha\Anaconda3\lib\site-packages\sklearn\utils\validation.py", line 382, in check_array
  array = np.array(array, dtype=dtype, order=order, copy=copy)
  
  ValueError: could not convert string to float: '44th week'
  </code></pre>