I'm having a dataset of 15 million rows with single column. It looks like,

```
x_raw
A1
A2
A3
A4
B1
B2
B3
B4
C1
C2

I want to convert it to

A1 A2 A3 A4
B1 B2 B3 B4
C1 C2 C3 C4

```

I was trying with 'for' loop, that will transpose every 4 rows, and add them to a 'final' dataframe, but as the dataset is too large, it'll iterate almost 2.7 million times which is not working that efficiently. Is there any other method or anything that I can use to do it efficiently?