pandas-filter-if-colunna--0-or-column-b-=-1

To filter a pandas dataframe based on column 'a' being greater than zero or column 'b' being equal to one, you can use the pipe operator '|' to combine two conditions into a single boolean mask.

Here's an example code snippet to filter a dataframe 'df' using this condition:

import pandas as pd

# create example dataframe
df = pd.DataFrame({'a': [-1, 0, 1, 2, 3], 'b': [0, 1, 0, 1, 0]})

# filter dataframe using boolean mask
mask = (df['a'] > 0) | (df['b'] == 1)
filtered_df = df[mask]

# print filtered dataframe
print(filtered_df)

This will output:

   a  b
1  0  1
2  1  0
3  2  1
4  3  0

Explanation:

• The boolean mask is created by combining two conditions using the '|' operator:
  • df['a'] > 0: this checks if each element in column 'a' is greater than zero
  • df['b'] == 1: this checks if each element in column 'b' is equal to one
• The resulting mask is a boolean array with the same length as the dataframe, where each element is True if the corresponding row satisfies either of the two conditions.
• The mask is passed to the dataframe indexing operator '[]' to select only the rows that satisfy the condition.
• The resulting filtered dataframe contains only the rows where either column 'a' is greater than zero, or column 'b' is equal to one.