CODEWITHSUNDEEP
pythonpandas
Alexis G
Alexis G

Reputation: 1339

Extract a column from a DataFrame

Just a basic question but which block me a lot. How can we extract a column from a DataFrame and have a DataFrame as output ?

Suppose that we have :

>>> dfM
<class 'pandas.core.frame.DataFrame'>
DatetimeIndex: 17544 entries, 2015-01-01 00:00:00 to 2016-12-31 23:00:00
Data columns (total 23 columns):
T1       17544  non-null values
T2       17544  non-null values

>>> df = dfM['T1']

Here df is not a DataFrame. I found a subterfuge by copy the DataFrame and del all columns but it's very time consumming.

Alexis

Upvotes: 0

Views: 3948

Answers (2)

David Robinson
David Robinson

Reputation: 78590

You can use [[]] instead of []:

df = dfM[['T1']]

For example:

from pandas import DataFrame
df = DataFrame(dict(a=range(10), b=range(10)))

type(df['b'])
# <class 'pandas.core.series.Series'>
type(df[['b']])
# <class 'pandas.core.frame.DataFrame'>

This works because it is passing a list of 1 (['b']) to the column subset operator.

Upvotes: 1

aha
aha

Reputation: 4604

One solution is to create a DataFrame with the column you want and the original index:

df = pandas.DataFrame(dfM.T1, index = dfM.index)

Upvotes: 0

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