如何在没有科学计数法且具有给定精度的情况下漂亮地打印numpy.array? [英] How to pretty-print a numpy.array without scientific notation and with given precision?

问题描述

我很好奇，是否有任何方式可以打印格式化的numpy.arrays，例如，类似于以下方式:

I'm curious, whether there is any way to print formatted numpy.arrays, e.g., in a way similar to this:

x = 1.23456
print '%.3f' % x

如果我想打印浮点数的numpy.array，它会以科学"格式打印几位小数，即使对于低维数组也很难阅读.但是，显然numpy.array必须打印为字符串，即使用%s.有解决方案吗?

If I want to print the numpy.array of floats, it prints several decimals, often in 'scientific' format, which is rather hard to read even for low-dimensional arrays. However, numpy.array apparently has to be printed as a string, i.e., with %s. Is there a solution for this?

推荐答案

您可以使用set_printoptions设置输出的精度:

You can use set_printoptions to set the precision of the output:

import numpy as np
x=np.random.random(10)
print(x)
# [ 0.07837821  0.48002108  0.41274116  0.82993414  0.77610352  0.1023732
#   0.51303098  0.4617183   0.33487207  0.71162095]

np.set_printoptions(precision=3)
print(x)
# [ 0.078  0.48   0.413  0.83   0.776  0.102  0.513  0.462  0.335  0.712]

suppress禁止对小数使用科学计数法:

And suppress suppresses the use of scientific notation for small numbers:

y=np.array([1.5e-10,1.5,1500])
print(y)
# [  1.500e-10   1.500e+00   1.500e+03]
np.set_printoptions(suppress=True)
print(y)
# [    0.      1.5  1500. ]

有关其他选项，请参见文档以获取set_printoptions

See the docs for set_printoptions for other options.

要使用NumPy 1.15.0或更高版本在本地应用打印选项，您可以使用

To apply print options locally, using NumPy 1.15.0 or later, you could use the numpy.printoptions context manager. For example, inside the with-suite precision=3 and suppress=True are set:

x = np.random.random(10)
with np.printoptions(precision=3, suppress=True):
    print(x)
    # [ 0.073  0.461  0.689  0.754  0.624  0.901  0.049  0.582  0.557  0.348]

但是在with-suite之外，打印选项又恢复为默认设置:

But outside the with-suite the print options are back to default settings:

print(x)    
# [ 0.07334334  0.46132615  0.68935231  0.75379645  0.62424021  0.90115836
#   0.04879837  0.58207504  0.55694118  0.34768638]

如果您使用的是NumPy的早期版本，则可以创建上下文管理器 你自己.例如，

If you are using an earlier version of NumPy, you can create the context manager yourself. For example,

import numpy as np
import contextlib

@contextlib.contextmanager
def printoptions(*args, **kwargs):
    original = np.get_printoptions()
    np.set_printoptions(*args, **kwargs)
    try:
        yield
    finally: 
        np.set_printoptions(**original)

x = np.random.random(10)
with printoptions(precision=3, suppress=True):
    print(x)
    # [ 0.073  0.461  0.689  0.754  0.624  0.901  0.049  0.582  0.557  0.348]

---

为防止浮点数结尾处的零被清除:

np.set_printoptions现在具有一个formatter参数，该参数使您可以为每种类型指定格式功能.

np.set_printoptions now has a formatter parameter which allows you to specify a format function for each type.

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

可打印

[ 0.078  0.480  0.413  0.830  0.776  0.102  0.513  0.462  0.335  0.712]

代替

[ 0.078  0.48   0.413  0.83   0.776  0.102  0.513  0.462  0.335  0.712]

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