SettingWithCopyWarning and pd.cut 
When I run the code below, i get the SettingWithCopyWarning and I am unsure of what I am doing wrong. Is there a way to code without the warning?

```
for chrom, df in grouped:
    bins = np.arange(0, 2e6, 1e5)
    df.ix[:,'Bins'] = pd.cut(df.Pos, bins)
```

A value is trying to be set on a copy of a slice from a DataFrame.
Try using .loc[row_indexer,col_indexer] = value instead
