horatio1701d - 4 months ago 76

Python Question

How can one modify the format for the output from a groupby operation in pandas that produces scientific notation for very large numbers. I know how to do string formatting in pythong but I'm at a loss when it comes to applying it here.

`df1.groupby('dept')['data1'].sum()`

dept

value1 1.192433e+08

value2 1.293066e+08

value3 1.077142e+08

This suppresses the scientific notation if I convert to string but now I'm just wondering how to string format and add decimals.

`sum_sales_dept.astype(str)`

Answer

Granted, the answer I linked in the comments is not very helpful. You can specify your own string converter like so.

```
In [25]: pd.set_option('display.float_format', lambda x: '%.3f' % x)
In [28]: Series(np.random.randn(3))*1000000000
Out[28]:
0 -757322420.605
1 -1436160588.997
2 -1235116117.064
dtype: float64
```

I'm not sure if that's the preferred way to do this, but it works.

Converting numbers to strings purely for aesthetic purposes seems like a bad idea, but if you have a good reason, this is one way:

```
In [6]: Series(np.random.randn(3)).apply(lambda x: '%.3f' % x)
Out[6]:
0 0.026
1 -0.482
2 -0.694
dtype: object
```