BUG: display.precision option seems off-by-one · Issue #10451 · pandas-dev/pandas (original) (raw)

I may very well be wrong on this, given how common an option it seems, but I am surprised that the "display.precision" option seems to limit the digits after the decimal to one less than specified.

In [1]: x = pd.Series(np.random.randn(5))

In [2]: x Out[2]: 0 -0.163960 1 1.016273 2 0.861317 3 -0.521916 4 -0.069322 dtype: float64

In [3]: pd.set_option('display.precision', 3)

In [4]: x Out[4]: 0 -0.16 1 1.02 2 0.86 3 -0.52 4 -0.07 dtype: float64

I can't see where in the code this is happening. At first glance, this looks like what the code is doing:

In [13]: fmt_str = '%% .%dg' % 3

In [14]: fmt_str % x[0]
Out[14]: '-0.164'

but clearly something else is happening.

numpy's precision seems fine/meets my expectations:

In [10]: np.set_printoptions(precision=3)

In [11]: np.random.randn(5) Out[11]: array([ 0.569, -2.638, 0.707, 0.675, 1.191])

So is this a bug? (if so it's been around for a long time) Or are my expectations off?

This was tested on current pandas master (as of writing) with numpy 1.9.2 and python 3.4.