We all know how to get the first or last five rows of a dataset. But did you know you can also retrieve the middle rows? Below is a dataframe showing cereal brands:
shape: (77, 4)
| str |
str |
i64 |
i64 |
| "Nabisco" |
"Cold" |
70 |
4 |
| "Quaker Oats" |
"Cold" |
120 |
3 |
| "Kellogs" |
"Cold" |
70 |
4 |
| "Kellogs" |
"Cold" |
50 |
4 |
| "Ralston Purina" |
"Cold" |
110 |
2 |
| … |
… |
… |
… |
| "General Mills" |
"Cold" |
110 |
2 |
| "General Mills" |
"Cold" |
110 |
1 |
| "Ralston Purina" |
"Cold" |
100 |
3 |
| "General Mills" |
"Cold" |
100 |
3 |
| "General Mills" |
"Cold" |
110 |
2 |
Get middle rows
With the slice method, Polars allows you to retrieve middle rows from your dataframe. Let’s get 20 rows starting from the 10th row:
shape: (20, 4)
| str |
str |
i64 |
i64 |
| "Quaker Oats" |
"Cold" |
120 |
1 |
| "General Mills" |
"Cold" |
110 |
6 |
| "General Mills" |
"Cold" |
120 |
1 |
| "General Mills" |
"Cold" |
110 |
3 |
| "General Mills" |
"Cold" |
110 |
1 |
| … |
… |
… |
… |
| "Kellogs" |
"Cold" |
110 |
1 |
| "Kellogs" |
"Cold" |
100 |
3 |
| "Post" |
"Cold" |
120 |
3 |
| "Kellogs" |
"Cold" |
120 |
3 |
| "Post" |
"Cold" |
110 |
1 |
As you can see from the code above, slice takes two parameters. The first is the position (index) of the starting row, and the second is the number of rows to return. In this case, the resulting dataframe will have 20 rows.
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