CODEWITHSUNDEEP
pythonstringpandasnumpydataframe
gabboshow
gabboshow

Reputation: 5559

modify strings in pandas dataframe column

I want to make all strings lower case and remove the whitespaces at the beginning and end of the strings.

df = pandas.DataFrame(data=[1,2,3,'A'],columns=['A'])
df['A'] = numpy.where(
    df['A'].apply(lambda x: isinstance(x, str)),
    df['A'].str.lower().str.strip(),
    df['A'],
)

The problem is that the code above fails if none of the rows is a string.

df = pandas.DataFrame(data=[1,2,3],columns=['A'])
AttributeError: Can only use .str accessor with string values, which use np.object_ dtype in pandas

Is there a better way to do this than

for index in df['A'].index:
    if isinstance(df['A'].iloc[index], str):
        df['A'].iloc[index] = df['A'].iloc[index].str.lower().str.strip()

Upvotes: 0

Views: 1414

Answers (1)

Tarifazo
Tarifazo

Reputation: 4343

Assuming you want to leave your non strings untouched, you can use:

df['A']=df['A'].apply(lambda x: x.lower().strip() if isinstance(x, str) else x)

Upvotes: 4

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