mattia wrote:
Il Fri, 16 Oct 2009 21:04:08 +0000, mattia ha scritto:
Is there a way to print to an unbuffered output (like stdout)? I've seen
that something like sys.stdout.write("hello") works but it also prints
the number of characters!
Another question (always py3). How can I print only the first number
after the comma of a division?
e.g. print(8/3) --> 2.66666666667
I just want 2.6 (or 2.66)
Thanks, Mattia
Just as sys.stdout.write() is preferable to print() for your previous
question, understanding str.format() is important to having good control
over what your output looks like. It's certainly not the only way, but
the docs seem to say it's the preferred way in version 3.x It was
introduced in 2.6, so there are other approaches you might want if you
need to work in 2.5 or earlier.
x = 8/3
dummy0=dummy1=dummy2=42
s = "The answer is approx. {3:07.2f} after rounding".format(dummy0,
dummy1, dummy2, x)
print(s)
will print out the following:
The answer is approx. 0002.67 after rounding
A brief explanation of the format string {3:07.2f} is as follows:
3 selects argument 3 of the function, which is x
0 means to zero-fill the value after conversion
7 means 7 characters total width (this helps determine who many
zeroes are inserted)
2 means 2 digits after the decimal
f means fixed point format
You can generally leave out the parts you don't need, but this gives you
lots of control over what things should look like. There are lots of
other parts, but this is most of what you might need for controlled
printing of floats.
The only difference from what you asked is that this rounds, where you
seemed (!) to be asking for truncation of the extra columns. If you
really need to truncate, I'd recommend using str() to get a string, then
use index() to locate the decimal separator, and then slice it yourself.
DaveA
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