How to printing numpy array with 3 decimal places? [duplicate]

Question

How can I print numpy array with 3 decimal places? I tried array.round(3) but it keeps printing like this 6.000e-01. Is there an option to make it print like this: 6.000?

I got one solution as print ("%0.3f" % arr), but I want a global solution i.e. not doing that every time I want to check the array contents.

Answer 1

 np.set_printoptions(formatter={'float': lambda x: "{0:0.3f}".format(x)}) 

This will set numpy to use this lambda function for formatting every float it prints out.

other types you can define formatting for (from the docstring of the function)

    - 'bool'     - 'int'     - 'timedelta' : a `numpy.timedelta64`     - 'datetime' : a `numpy.datetime64`     - 'float'     - 'longfloat' : 128-bit floats     - 'complexfloat'     - 'longcomplexfloat' : composed of two 128-bit floats     - 'numpy_str' : types `numpy.string_` and `numpy.unicode_`     - 'str' : all other strings  Other keys that can be used to set a group of types at once are::      - 'all' : sets all types     - 'int_kind' : sets 'int'     - 'float_kind' : sets 'float' and 'longfloat'     - 'complex_kind' : sets 'complexfloat' and 'longcomplexfloat'     - 'str_kind' : sets 'str' and 'numpystr' 

Answer 2

Actually what you need is np.set_printoptions(precision=3). There are a lot of helpful other parameters there.

For example:

np.random.seed(seed=0) a = np.random.rand(3, 2) print a np.set_printoptions(precision=3) print a 

will show you the following:

[[ 0.5488135   0.71518937]  [ 0.60276338  0.54488318]  [ 0.4236548   0.64589411]] [[ 0.549  0.715]  [ 0.603  0.545]  [ 0.424  0.646]]