Question

I have some data here in a text file which I have use regular expression to parse the data
from the file and store the number and index in two variables. I would like to rounded the numbers to same decimal place and write it into a new file (with it’s index A,B,C)

This set of data is all in 3 decimal place

A 11,000.233

B 4.000

C 14,798.241

Another set of data is in 2 decimal place

A 11,000.23

B 4.00

C 14,798.24

They are all in string format initially when I read them using readlines()

But when I convert the string in the first set of data to float and then round it from 3 decimal place to 2 decimal place by using str(round(float(number),2))

I have encountered two problems

1. It will give me an ValueError for A (11,000.233) and C (14,798.241)

   I understand it is caused by the , in 11,000.23. But I don’t know how to deal with it.Could anyone give me some suggestion on how to deal with it?

2. For B, when I try to convert the numbers with the same method, it give me 4.0 instead of 4.00. Is there anyway that can output 4.00 instead of 4.0?

Answer 1

split the string at "," and use "".join():

In [32]: strs="11,000.233"

In [33]: float("".join(strs.split(",")))
Out[33]: 11000.233

In [34]: strs="14,798.24"

In [35]: float("".join(strs.split(",")))
Out[35]: 14798.24

you can use string formatting to get 4.00:

In [36]: strs="4.00"

In [37]: float(strs)
Out[37]: 4.0

In [39]: format(float(strs),".2f")
Out[39]: '4.00'

In [40]: "{0:.2f}".format(float(strs))
Out[40]: '4.00'