[英]How to format floating-point number to x significant digits
I am looking to print a floating-point number to a number of significant digits, where I consider digits in front of the decimal separator as significant.我希望将浮点数打印为多个有效数字,我认为小数点分隔符前面的数字是有效的。 So with 3 significant digits, I would like the following:因此,使用 3 位有效数字,我想要以下内容:
1234.56 --> 1234
123.456 --> 123
12.3456 --> 12.3
1.23456 --> 1.23
.123456 --> 0.123
.012345 --> 0.0123
.0012345 --> 0.00123
Basically, I want to suppress the decimal fraction if it is not required, but I do not want to round the integer part.基本上,如果不需要,我想抑制小数部分,但我不想舍入 integer 部分。 (And I would like to avoid scientific notation.) (而且我想避免使用科学记数法。)
How can I achieve that?我怎样才能做到这一点? I tried a number of ways, but none really do what I want.我尝试了很多方法,但没有一个能真正做到我想要的。
This is close, but uses scientific notation:这很接近,但使用科学记数法:
for x in [1234.56, 123.456, 12.3456, 1.23456, .123456, .012345, .0012345]:
print(x, " --> ", f"{x:.3g}")
1234.56 --> 1.23e+03 # wrong!
123.456 --> 123
12.3456 --> 12.3
1.23456 --> 1.23
0.123456 --> 0.123
0.012345 --> 0.0123
0.0012345 --> 0.00123
In such conditions you can try like this在这种情况下,您可以尝试这样
for f in [1234.56, 123.456, 12.3456, 1.23456, .123456, .012345, .0012345]:
dp= str(f)[::-1].find('.')
#print(dp)
if dp <=3:
fs= int(f)
print(f, "-->",fs)
else:
print(f, " --> ", f"{f:.3g}")
output: output:
1234.56 --> 1234
123.456 --> 123
12.3456 --> 12.3
1.23456 --> 1.23
0.123456 --> 0.123
0.012345 --> 0.0123
0.0012345 --> 0.00123
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