Vitto - 1 year ago 149

Python Question

I am looking at the numpy.savetxt, and am stuck at the fmt option.

I tried looking at here and also the reference in the link below all the letters that can be used for the fmt option sort give me a general sense of what is going on.

What I do not understand is if the "%" symbol is required and in an example given here how should I interpret the 10.5 number ?

If "f" is about setting the floating point, then how come is it 10.5 (then again, I might not know how floating points are set...).

Thanks!

Answer Source

You can use the `fmt`

parameter in many ways, here are some examples to give you some insight.

```
import numpy as np
a = np.array([[11,12,13,14],
[21,22,23,24]])
```

1) `np.savetxt('tmp.txt',a, fmt='%1.3f')`

```
11.000 12.000 13.000 14.000
21.000 22.000 23.000 24.000
```

2) `np.savetxt('tmp.txt',a, fmt='%04d')`

```
0011 0012 0013 0014
0021 0022 0023 0024
```

You can also use to write expressions, like (note that the number of entries in the expression is the same as the number of columns in the array:

3) `np.savetxt('tmp.txt',a, fmt='%1.1f + %1.1f / (%1.1f * %1.1f)')`

```
11.0 + 12.0 / (13.0 * 14.0)
21.0 + 22.0 / (23.0 * 24.0)
```