NHSDigital
diff --git a/‎codonPython/check_null.py‎
Lines changed: 16 additions & 10 deletions b/‎codonPython/check_null.py‎
Lines changed: 16 additions & 10 deletions
@@ -1,29 +1,35 @@
 import numpy
 import pandas as pd
 
-def check_null(dataframe: pd.DataFrame) -> bool:
+def check_null(dataframe: pd.DataFrame, columns_to_be_checked: list) -> bool:
     """
     Checks a pandas dataframe for null values
 
-    This function takes a pandas dataframe supplied as an argument and returns a boolean value representing any null values contained
+    This function takes a pandas dataframe supplied as an argument and returns a integer value representing any null values found within the columns to check
 
     Parameters
     ----------
     data : pandas.DataFrame
-        Dataframe to be checked for null values
+        Dataframe to read
+    columns_to_be_checked: list
+        Given dataframe columns to be checked for null values
 
     Returns
     -------
-    out : bool
-        A True or False response based on if a dataframe contains null values
+    out : int
+        The number of null values found in the given columns
 
     Examples
     --------
-    >>> check_null(dataframe = pd.DataFrame({'col1': [1,2], 'col2': [3,4]}))
-    False
-    >>> check_null(dataframe = pd.DataFrame({'col1': [1,numpy.nan], 'col2': [3,4]}))
-    True
+    >>> check_null(dataframe = pd.DataFrame({'col1': [1,2], 'col2': [3,4]}), columns_to_check = ['col1'])
+    0
+    >>> check_null(dataframe = pd.DataFrame({'col1': [1,numpy.nan], 'col2': [3,4]}), columns_to_check = ['col1'])
+    1
     """
-    null_count = dataframe.isnull().values.any()
+
+    null_count = 0
+    for eachColumn in columns_to_be_checked:
+        prev_null_count = null_count
+        null_count = prev_null_count + (len(dataframe) - dataframe[eachColumn].count())
 
     return null_count