CODEWITHSUNDEEP
pythonpython-3.xpandas
Javier Monsalve
Javier Monsalve

Reputation: 326

Filter rows in Pandas using a chained condition

I have an initial csv file that contains certian values that I am interested in, and I would like to read it and to filter it at the same time.

The file has the following structure:

A B
25 xx
NaN yy
32 zz
25 zz

What I normally do is read it first and then, apply the filter:

df = pd.read_csv(filename, sep=";")
df = df[df['A']==25]

I would like to know if it is possible to filter it in a chained way such as the following:

df = pd.read_csv(filename, sep=";")\
.where('A'==25)

Upvotes: 1

Views: 260

Answers (1)

jezrael
jezrael

Reputation: 863541

If need remove missing rows use DataFrame.query with trick for compare if A is same like A, because np.nan != np.nan:

df = pd.read_csv(filename, sep=";").query('A==A')

Or use selection by callable:

df = pd.read_csv(filename, sep=";").loc[lambda x: x.A.notna()]

If need test another values:

df = pd.read_csv(filename, sep=";").query('A==25')

Or:

df = pd.read_csv(filename, sep=";").loc[lambda x: x.A == 25]

Upvotes: 1

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