Update README.md

README.md

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-# eland
-Python elasticsearch client implementing a pandas-like DataFrame API
+## What is it?
+
+eland is a elasticsearch client Python package to analyse, explore and manipulate data that resides in elasticsearch. Where possible the package uses existing Python APIs and data structures to make it easy to switch between Numpy, Pandas, Scikit-learn to their elasticsearch powered equivalents. In general, the data resides in elasticsearch and not in memory, which allows eland to access large datasets stored in elasticsearch.
+
+For example, to explore data in a large elasticsearch index, simply create an eland DataFrame from an elasticsearch index pattern, and explore using an API that mirrors a subset of the pandas.DataFrame API: 
+
+```
+>>> import eland as ed
+
+>>> df = ed.read_es(url='http://localhost:9200', index='reviews') 
+
+>>> type(df)
+<class 'eland.core.frame.DataFrame'>
+
+>>> df.head()
+   reviewerId  vendorId  rating              date
+0           0         0       5  2006-04-07 17:08
+1           1         1       5  2006-05-04 12:16
+2           2         2       4  2006-04-21 12:26
+3           3         3       5  2006-04-18 15:48
+4           3         4       5  2006-04-18 15:49
+
+>>> df.describe()
+          reviewerId       vendorId         rating
+count  578805.000000  578805.000000  578805.000000
+mean   174124.098437      60.645267       4.679671
+std    116951.972209      54.488053       0.800891
+min         0.000000       0.000000       0.000000
+25%     70043.000000      20.000000       5.000000
+50%    161052.000000      44.000000       5.000000
+75%    272697.000000      83.000000       5.000000
+max    400140.000000     246.000000       5.000000
+```
+