diff --git a/Makefile b/Makefile
index 99d9b0f..a6d1dab 100644
--- a/Makefile
+++ b/Makefile
@@ -1,4 +1,4 @@
-.PHONY: clean clean-test clean-pyc clean-build docs help
+.PHONY: clean clean-test clean-pyc clean-build docs help prepareenv
 .DEFAULT_GOAL := help
 
 define BROWSER_PYSCRIPT
@@ -82,13 +82,16 @@ tox:  ## run fully isolated tests with tox
 install:  ## install updated project.toml with flint
 	flit install --pth-file
 
-devenv: ## setup development environment
+prepareenv: ## setup a virtualenv and install basic reuqired packages
 	python3 -m venv --prompt sensospot_tools .venv
 	.venv/bin/pip3 install --upgrade pip
 	.venv/bin/pip3 install "flit>3.2"
 	.venv/bin/flit install --pth-file
 
-repo: devenv ## complete project setup with development environment and git repo
+devenv: prepareenv ## setup development environment including pre commit hooks
+	.venv/bin/pre-commit install --install-hooks
+
+repo: prepareenv ## complete project setup with development environment and git repo
 	git init .
 	git add .
 	git commit -m "import of project template"
diff --git a/README.md b/README.md
index 709a6a6..a92b42e 100644
--- a/README.md
+++ b/README.md
@@ -3,13 +3,65 @@ Sensospot Tools
 
 Some small tools for working with parsed Sensospot data.
 
-## Example:
+## Selecting and spliting a pandas data frame
 
+### sensospot_tools.select(data: DataFrame, column: str, value: Any) -> DataFrame
+
+Selects rows of a dataframe based on a value in a column
+
+Example:
+```python
+
+    from sensospot_tools import select
+
+    print(data)
+        category  value
+    0      dog      1
+    1      cat      2
+    2    horse      3
+    3      cat      4
+
+    print(select(data, "category", "cat"))
+          category  value
+        1      cat      2
+        3      cat      4
+```
+
+
+### sensospot_tools.split(data: DataFrame, column: str) -> Iterator[tuple[Any, DataFrame]]
+
+Splits a data frame on unique values in a column
+
+Returns an iterator where each result is key-value-pair. The key is the
+unique value used for the split, the value is a slice of the dataframe
+selected by the unique value contained in the column.
+
+Example:
 ```python
 
-    import sensospot_tools
+    from sensospot_tools import split
+
+    print(data)
+        category  value
+    0      dog      1
+    1      cat      2
+    2    horse      3
+    3      cat      4
+
+    result = dict( split(data, column="category") )
+
+    print(result["dog"])
+        category  value
+    0      dog      1
+
+    print(result["cat"])
+        category  value
+    1      cat      2
+    3      cat      4
 
-    sensospot_tools.run()
+    print(result["horse"])
+        category  value
+    2    horse      3
 ```
 
 
diff --git a/src/sensospot_tools/selection.py b/src/sensospot_tools/selection.py
index e9d708b..ebd26a2 100644
--- a/src/sensospot_tools/selection.py
+++ b/src/sensospot_tools/selection.py
@@ -6,7 +6,7 @@ import pandas
 def select(
     data: pandas.DataFrame, column: str, value: Any
 ) -> pandas.DataFrame:
-    """selects a portion of a dataframe based by a value in a column
+    """Selects rows of a dataframe based on a value in a column
 
     Example:
     >>> print(data)
@@ -34,7 +34,7 @@ def select(
 def split(
     data: pandas.DataFrame, column: str
 ) -> Iterator[tuple[Any, pandas.DataFrame]]:
-    """splits a data frame by unique values in a column
+    """Splits a data frame on unique values in a column
 
     returns an iterator where each result is key-value-pair. The key is the
     unique value used for the split, the value is a slice of the dataframe