How To Find Missing Values In A DataFrame?


How To Find Missing Values In A DataFrame?

Table Of Contents:

  1. Syntax ‘isna( )’ Method In Pandas.
  2. Examples ‘isna( )’ Method.

(1) Syntax:

DataFrame.isna()

Description:

  • Detect missing values.

  • Return a boolean same-sized object indicating if the values are NA. NA values, such as None or numpy.NaN, gets mapped to True values.

  • Everything else gets mapped to False values. Characters such as empty strings '' or numpy.inf are not considered NA values (unless you set pandas.options.mode.use_inf_as_na = True).

Returns:

  • DataFrame
    • Mask of bool values for each element in DataFrame that indicates whether an element is an NA value.

(2) Examples Of isna() Method:

Example-1:

df = pd.DataFrame(dict(age=[5, 6, np.NaN],
                   born=[pd.NaT, pd.Timestamp('1939-05-27'),
                         pd.Timestamp('1940-04-25')],
                   name=['Alfred', 'Batman', ''],
                   toy=[None, 'Batmobile', 'Joker']))
df

Output:

# Show which entries in a DataFrame are NA.

df.isna()

Output:

# Count Of Missing Values In Each Column

df.isna().sum()

Output:

age     1
born    1
name    0
toy     1
dtype: int64

# Percentage Of Missing Values In Each Column

(df.isna().sum()/len(df))*100

Output:

age     33.333333
born    33.333333
name     0.000000
toy     33.333333
dtype: float64

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