How to check if a certain df['column'] contains a word from a list Python?-CodePudding

Any tips on how to see if a certain word is inside pandas column?

# initialise data of lists.
data = {'Colour':['Blue andtext', 'Greys', 'Potato', 'Yellow','Tree'],
        'Values':[20, 21, 19, 18,44]}
 
df2 = pd.DataFrame(data)

Let's say:

colours = ['Blue','Grey','Yellow']

How do I check if df2['Colour'] is actually a colour and represent it in a new column?

Output should be

Colour           Value   Actualcolour
Blue andtext     20      Blue
Greys            21      Grey
Potato           19      NaN
Yellow           18      Yellow
Tree             44      Nan

CodePudding user response：

How about this?

df2['ActualColour'] = [x if x in colours else np.NaN for x in df2.Colour]

You could also convert colours into a df and left join them

CodePudding user response：

Use pd.Series.where and isin:

df2["Actualcolour"] = df2["Colour"].where(df2["Colour"].isin(colours))

print (df2)

   Colour  Values Actualcolour
0    Blue      20         Blue
1    Grey      21         Grey
2  Potato      19          NaN
3  Yellow      18       Yellow
4    Tree      44          NaN

Or use pd.Series.extract and add word boundary or ignore case if required:

df2["ActualColor"] = df2["Colour"].str.extract(f"({'|'.join(colours)})")

print (df2)

         Colour  Values ActualColor
0  Blue andtext      20        Blue
1         Greys      21        Grey
2        Potato      19         NaN
3        Yellow      18      Yellow
4          Tree      44         NaN

CodePudding user response：

Another possible answer is to apply a function to the column in question using .apply:

df2["ActualColour"] = df2["Colour"].apply(lambda x: x if x in colours else np.nan)