python subset code example

Example 1: dataframe slice by list of values

In [1]: df = pd.DataFrame({'A': [5,6,3,4], 'B': [1,2,3,5]})

In [2]: df
Out[2]:
   A  B
0  5  1
1  6  2
2  3  3
3  4  5

In [3]: df[df['A'].isin([3, 6])]
Out[3]:
   A  B
1  6  2
2  3  3

Example 2: python subset

# Creating sets
A = {1, 2, 3}
B = {1, 2, 3, 4, 5}

# Checking if A is subset of B (vice versa)
# Returns True
# A is subset of B
print(A.issubset(B))

# Returns False
# B is not subset of A
print(B.issubset(A))

Example 3: python - row slice dataframe by number of rows

df.iloc[[1, 5]]                                               # Get rows 1 and 5
df.iloc[1:6]                                                  # Get rows 1 to 5 inclusive
df.iloc[[1, 5], df.columns.get_loc('Shop')]                   # Get only specific column
df.iloc[[1, 5], df.columns.get_indexer(['Shop', 'Category'])] # Get multiple columns

Example 4: select columns to include in new dataframe in python

new = old.filter(['A','B','D'], axis=1)

Example 5: how to check if a list is a subset of another list

if(all(x in test_list for x in sub_list)): 
  flag = True