Selecting multiple rows from a dataframe using a column

Question

So, I have a dataframe with a lot of rows and I'm trying to select just a column of some of those rows using a column of data. is there a command that asks for a column with certain values and returns the rows that contain that column? Oh, and I want to select just a column of the rows that are returned.

Answer 1

You are looking for df.loc

For example:

df.loc[df['col1']==3]

Returns all rows where col1 == 3

Or:

df.loc[df['col1']==3, ['col2', 'col1']]

Returns a dataframe like the one above but it only has col1 and col2

Answer 2

The documentation has a quick guide to this.

For selecting rows that meet a particular condition, you can use brackets.

df[(condtion)]
# ex.
df[df['A'] > 3]

That returns a subsetted dataframe, so you can select columns like you usually would.

df[df['A'] > 3][['A', 'B']]