I have a DataFrame like this:
a b
A 1 0
B 0 1
and I have an array ["A","B","C"].
From these, I want to create a new DataFrame like this:
a b
A 1 0
B 0 1
C NaN NaN
How can I do this?
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2 Answers
Assuming I understand what you're after (setting aside weird duplicated-index cases), one way is to use loc to index into your frame:
>>> df = pd.DataFrame({'a': {'A': 1, 'B': 0}, 'b': {'A': 0, 'B': 1}})
>>> arr = ["A", "B", "C"]
>>> df
a b
A 1 0
B 0 1
>>> df.loc[arr]
a b
A 1 0
B 0 1
C NaN NaN
Comments
Create an DataFrame with only index=['C'] and concat:
df = pd.DataFrame({'a': {'A': 1, 'B': 0}, 'b': {'A': 0, 'B': 1}}
df = pd.concat([df, pd.DataFrame(index=['C'])])
