added warning to align function when n_features exceeds n_samples

hypertools/tools/align.py

@@ -25,6 +25,7 @@
 from .procrustes import procrustes
 import numpy as np
 from .._shared.helpers import format_data
+from warnings import warn
 
 ##MAIN FUNCTION##
 def align(data, method='hyper'):
@@ -63,6 +64,11 @@ def align(data, method='hyper'):
 
     data = format_data(data)
 
+    if data[0].shape[1]>=data[0].shape[0]:
+        warn('The number of features exceeds number of samples. This can lead \
+             to overfitting.  We recommend reducing the dimensionality to be \
+             less than the number of samples prior to hyperalignment.')
+
     if method=='hyper':
 
         ##STEP 0: STANDARDIZE SIZE AND SHAPE##