Compare Values Under Multiple Conditions Of One Column In Python

I have the following data: data = { 'index': [1, 2, 3, 4, 5], 'name': ['A', 'A', 'B', 'B', 'B'], 'type': ['s1', 's2', 's1', 's2', 's3'], 'value': [20, 10, 18, 32, 2

Solution 1:

Try:

#Use pd.Categorical to ensure sorting if column is not lexicographical ordered.
df['type'] = pd.Categorical(df['type'], ordered=True, categories=['s1','s2','s3'])

df['result'] = df.sort_values('type').groupby('name')['value'].diff(-1)

df['result'] = df['result'].lt(0).mask(df['result'].isna(),'')

df

Output:

   index name type  value result
0      1    A   s1     20  False
1      2    A   s2     10       
2      3    B   s1     18   True
3      4    B   s2     32  False
4      5    B   s3     25