# How do I calculate percentiles with python/numpy?

You might be interested in the SciPy Stats package. It has the percentile function you're after and many other statistical goodies.

`percentile()`

is available in `numpy`

too.

`import numpy as npa = np.array([1,2,3,4,5])p = np.percentile(a, 50) # return 50th percentile, e.g median.print p3.0`

~~This ticket leads me to believe they won't be integrating ~~`percentile()`

into numpy anytime soon.

By the way, there is a pure-Python implementation of percentile function, in case one doesn't want to depend on scipy. The function is copied below:

`## {{{ http://code.activestate.com/recipes/511478/ (r1)import mathimport functoolsdef percentile(N, percent, key=lambda x:x): """ Find the percentile of a list of values. @parameter N - is a list of values. Note N MUST BE already sorted. @parameter percent - a float value from 0.0 to 1.0. @parameter key - optional key function to compute value from each element of N. @return - the percentile of the values """ if not N: return None k = (len(N)-1) * percent f = math.floor(k) c = math.ceil(k) if f == c: return key(N[int(k)]) d0 = key(N[int(f)]) * (c-k) d1 = key(N[int(c)]) * (k-f) return d0+d1# median is 50th percentile.median = functools.partial(percentile, percent=0.5)## end of http://code.activestate.com/recipes/511478/ }}}`

`import numpy as npa = [154, 400, 1124, 82, 94, 108]print np.percentile(a,95) # gives the 95th percentile`