df.insert(2, 's', ' ', 1)
df.insert(1, 's', ' ', 1)
return df.sum(1)

def pir2(df):
    df = df.copy()
return pd.MultiIndex.from_arrays(df.values.T).to_series().str.join(' '
    ).reset_index(drop=True)

def pir3(df):
    a = df.values[:, (0)].copy()
for j in range(1, df.shape[1]):
    a += ' ' + df.values[:, (j)]
return pd.Series(a)
Merging data frame columns of strings into one single column in Pandas