检查列表中的截断的元组值？

Question

我有一个元组列表

In [142]: mylist=[(0.0, 0.0), (0.0, 0.769883), (-0.01435677, 1.7573411), (-0.3796871, -0.40361387), (-0.27704585, -1.7006601), (-0.26976547, -2.6480746), (-0.27020714, -3.0438666), (-0.2759932, -3.638946), (-0.28580084, -4.182567), (-0.29590216, -4.5594716), (-0.31486654, -5.1321993), (-0.3386181, -5.701327), (-0.37045696, -6.34038), (-0.40544215, -6.94697), (-0.45580167, -7.711907), (-0.48936173, -8.165736), (-0.52177864, -8.558438), (-0.5721365, -9.112968), (-0.6326114, -9.723627), (-0.6764244, -10.130929), (-0.7162372, -10.471702), (-0.73864824, -11.2733345), (-0.6795322, -11.688038), (-0.6065086, -12.021755), (-0.52627456, -12.4043045), (-0.42850703, -13.172687), (-0.2827803, -15.462493), (-0.25139827, -16.006815), (-0.21802832, -16.84582)]

我要检查这个元组是否(-0.405442, -6.94697)是mylist与否。

(-0.40544215, -6.94697)在下面的列表中：

In [143]: mylist[13]
Out[143]: (-0.40544215, -6.94697)

但是我的查询元组已被截断为(-0.405442, -6.94697) 。

如何让Python告诉我(-0.405442, -6.94697)在mylist （忽略截断）？

Answer 1

(-0.405442, -6.94697)不在您的列表中。 (-0.40544215, -6.94697)是

如果要检查元组是否以6位小数位数的精度在列表中，请尝试执行此操作

(-0.405442, -6.94697) in [(round(i[0], 6), round(i[1], 6)) for i in mylist]

如果要多次检查，最好还是创建一个新列表：

mynewlist = [(round(i[0], 6), round(i[1], 6)) for i in mylist]
(-0.405442, -6.94697) in mynewlist

Answer 2

因为（ -0.405442 ，-6.94697）与（ -0.40544215 ，-6.94697）不同

>>> mylist=[(0.0, 0.0), (0.0, 0.769883), (-0.01435677, 1.7573411), (-0.3796871, -0.40361387), (-0.27704585, -1.7006601), (-0.26976547, -2.6480746), (-0.27020714, -3.0438666), (-0.2759932, -3.638946), (-0.28580084, -4.182567), (-0.29590216, -4.5594716), (-0.31486654, -5.1321993), (-0.3386181, -5.701327), (-0.37045696, -6.34038), (-0.40544215, -6.94697), (-0.45580167, -7.711907), (-0.48936173, -8.165736), (-0.52177864, -8.558438), (-0.5721365, -9.112968), (-0.6326114, -9.723627), (-0.6764244, -10.130929), (-0.7162372, -10.471702), (-0.73864824, -11.2733345), (-0.6795322, -11.688038), (-0.6065086, -12.021755), (-0.52627456, -12.4043045), (-0.42850703, -13.172687), (-0.2827803, -15.462493), (-0.25139827, -16.006815), (-0.21802832, -16.84582)]
>>> (-0.40544215, -6.94697) in mylist
True

*除非有错字。

Answer 3

如果要使用理解力查找近似匹配项，则可以通过检查所需数字减去所找到数字的绝对值是否小于某个极限来检查该数字是否“足够接近”所需值。

>>> [(x,y) for (x,y) in mylist if abs(-0.405442-x)<0.001 and abs(-6.94697-y)<0.001]

[(-0.40544215, -6.94697)]

...将找到在您期望值的0.001以内的值。