float to string with different precision

[zunbeltz]

Hi,

I have to print float numbers to a file. Each float should be 5
characters in width (4 numbers and the decimal point).
My problem is that I do not now how to specify float to have different
numbers of decimals. For example

5.32 -5.320
10.356634 -10.357
289.234 -289.2

In the string formating operations only fixed number of decimal digits
is allow.

Thanks in advance for the help,

Zunbeltz

[Peter Otten]

zu******@gmail.com wrote:

I have to print float numbers to a file. Each float should be 5
characters in width (4 numbers and the decimal point).
My problem is that I do not now how to specify float to have different
numbers of decimals. For example

5.32 -5.320
10.356634 -10.357
289.234 -289.2

In the string formating operations only fixed number of decimal digits
is allow.

>>["%#.4g" % f for f in [5.32, 10.356634, 289.234, 123456789.]]

['5.320', '10.36', '289.2', '1.235e+08']

Found by playing around with format strings, so no guarantees.

Peter

[Zentrader]

On Aug 10, 1:12 am, Peter Otten <[e-mail]:

[e-mail] wrote:

I have to print float numbers to a file. Each float should be 5
characters in width (4 numbers and the decimal point).
My problem is that I do not now how to specify float to have different
numbers of decimals. For example

5.32 -5.320
10.356634 -10.357
289.234 -289.2

In the string formating operations only fixed number of decimal digits
is allow.

>["%#.4g" % f for f in [5.32, 10.356634, 289.234, 123456789.]]

['5.320', '10.36', '289.2', '1.235e+08']

Found by playing around with format strings, so no guarantees.

Peter

If the above does not work
[/code]test_list = [ 5.32, 10.35634, 289.234 ]
for num in test_list :
str_num = "%11.5f" % (num) ## expand to at least 5
print str_num, "-->", str_num.strip()[:5][/code]

[Roger Miller]

On Aug 10, 8:37 am, Zentrader <[e-mail]:

>
If the above does not work
[/code]test_list = [ 5.32, 10.35634, 289.234 ]
for num in test_list :
str_num = "%11.5f" % (num) ## expand to at least 5
print str_num, "-->", str_num.strip()[:5][/code]

This has the disadvantage that it doesn't round the last digit. For
example 10.356634 yields 10.356 instead of 10.357.

You can use '*' in format strings to take a numeric field value from a
variable. For example

ndecimals = 2
print "%5.*f" % (ndecimals, x)

formats x with 2 digits following the decimal point. Or you can
simply
cobble up a format string at run time:

format = "%%5.%df" % ndecimals
print format % x