I have data that I want to print to file. For missing data, I wish to print the mean of the actual data. However, the mean is calculated to more than the required 4 decimal places. How can I write to the mean to file and format this mean at the same time?
I have tried the following, but keep getting errors:
outfile.write('{0:%.3f}'.format(str(mean))+"\n")
First, remove the % since it makes your format syntax invalid. See a demonstration below:
>>> '{:%.3f}'.format(1.2345)
Traceback (most recent call last):
File "<stdin>", line 1, in <module>
ValueError: Invalid conversion specification
>>> '{:.3f}'.format(1.2345)
'1.234'
>>>
Second, don't put mean in str since str.format is expecting a float (that's what the f in the format syntax represents). Below is a demonstration of this bug:
>>> '{:.3f}'.format('1.2345')
Traceback (most recent call last):
File "<stdin>", line 1, in <module>
ValueError: Unknown format code 'f' for object of type 'str'
>>> '{:.3f}'.format(1.2345)
'1.234'
>>>
Third, the +"\n" is unnecessary since you can put the "\n" in the string you used on str.format.
Finally, as shown in my demonstrations, you can remove the 0 since it is redundant.
In the end, the code should be like this:
outfile.write('{:.3f}\n'.format(mean))
You don't need to convert to string using str(). Also, the "%" is not required. Just use:
outfile.write('{0:.3f}'.format(mean)+"\n")
First of all, the formatting of your string has nothing to do with your write statement. You can reduce your problem to:
string = '{0:%.3f}'.format(str(mean))+"\n"
outfile.write(string)
Then, your string specification is incorrect and should be:
string = '{0:.3f}\n'.format(mean)
outfile.write('{.3f}\n'.format(mean))
