Capitalize a string column in pandas

Question

How to replace a multiple version in easiest way?

Here's my data:

No  Device
1   asus
2   Xiaomi
3   xiaomi
4   Asus
5   Samsung

I want to make it:

No  Device
1   Asus
2   Xiaomi
3   Xiaomi
4   Asus
5   Samsung

What I did is:

f = {'xiaomi':'Xiaomi', 'asus':'Asus'}
df['Device'] = df['Device'].map(f)

But the result is:

No  Device
1   Asus
2   NaN
3   Xiaomi
4   NaN
5   NaN

If `Asus BEST` then need `Asus best` (capitalize) or `Asus Best` (title)? — jezrael, May 28 '18 at 07:57

score 6 · Answer 1 · answered May 28 '18 at 07:43

6

Why not just go with str.title?

df['Device'] = df.Device.str.title()  
df

   No   Device
0   1     Asus
1   2   Xiaomi
2   3   Xiaomi
3   4     Asus
4   5  Samsung

There's no need for any mappings or dictionary this way.

answered May 28 '18 at 07:43

cs95

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704
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That was clever indeed haha – Bharath M Shetty May 28 '18 at 07:57

score 3 · Accepted Answer · answered May 28 '18 at 07:56

3

What you need is not mapping but replacing i.e

df['Device'] = df['Device'].replace(f)

0       Asus
1     Xiaomi
2     Xiaomi
3       Asus
4    Samsung
Name: Device, dtype: object

answered May 28 '18 at 07:56

Bharath M Shetty

30,075
6
57
108

1

Ya, to slow, rather not use. – jezrael May 28 '18 at 07:56
But its easy :) – Bharath M Shetty May 28 '18 at 07:56

jezrael · Answer 3 · 2018-05-28T07:49:15.040

Add fillna or combine_first if need dictionary and map:

df['Device'] = df['Device'].map(f).fillna(df['Device'])

Or:

df['Device'] = df['Device'].map(f).combine_first(df['Device'])

Or use only str.capitalize if need only first letter uppercase:

print (df)
   No     Device
0   1  asus best
1   2     Xiaomi
2   3     xiaomi
3   4       Asus
4   5    Samsung

df['Device'] = df['Device'].str.capitalize()
print (df)
   No     Device
0   1  Asus best
1   2     Xiaomi
2   3     Xiaomi
3   4       Asus
4   5    Samsung

Capitalize a string column in pandas

3 Answers3