Update readme

README.md

@@ -9,23 +9,45 @@ Parser for the [GLADE+ galaxy catalog](https://glade.elte.hu/).
 To read the catalog into a `pandas.DataFrame`:
 
 ```python
-from gladeparser import to_df
+from gladeparser import to_pandas_df
 
 filename = "path/to/catalog"
-df = to_df(filename)
+df = to_pandas_df(filename)
+```
+
+The preferred way of reading the catalog is using a `polars` backend, especially if you want to filter out the data:
+
+```python
+from gladeparser import to_polars_df
+import polars as pl
+
+# Grab objects from 2MASS catalog with redshifts corrected for peculiar velocity
+filters = (
+    pl.col("2MASS name").is_not_null(),
+    pl.col("z_cmb").is_not_null(),
+    pl.col("z_cmb") > 0,
+    pl.col("z flag") == 1,
+    pl.col("dist flag").is_in([1, 3])
+)
+
+# Selected columns
+cols = ["ra", "dec", "z_cmb"]
+
+filename = "path/to/catalog"
+df = to_polars_df(filename, cols=cols, **filters)
 ```
 
 ### Parsing a subset of columns
 
 ```python
-from gladeparser import to_df, get_columns
+from gladeparser import to_pandas_df, get_columns
 
 # Select the columns you want and return their names
 # See more options in get_columns docstring
 cols = get_columns('Localization', 'Distance', names=True)
 
 filename = "path/to/catalog"
-df = to_df(filename, cols=cols)
+df = to_pandas_df(filename, cols=cols)
 ```
 
 ## Installation