python: check type and ifno of a data frame

df.shape
df.info()
df.dtypes
des = df.describe()                        # Summary
des_num = df.describe(include=[np.number]) # Include only numerical columns
des_obj = df.describe(include=[np.object]) # Include only string columns
des_obj.transpose()

# Show list of variable / columns in DF
df.columns

# Count number of variables / columns in DF
len(df.columns)

# Count variable
df["myvar"].value_counts()