Giulia Marcoux wrote:
> Hello,
>
> I am a student learning python, and i am running into some difficulties. I
> am tryign to read a csv file that has different delimiters for different
> rows: Example:
>
> Format:V1.1
> Model: R
> Step Size: 10mm
> Distance: 10cm
> Gain: 1000
>
> X,Y
> 1,3
> 2,5
> 6,5
> 5,7
>
> For the X,Y data, I have no problem getting it into the right cells,
> however I cannot separate the values after the colon for the first few
> rows. Its either one or the other. I am using pandas to read my CSV file.
> So far I have:
>
> d=pd.read_csv('read.csv',delimiter=',',skiprows=0)
>
> When I replace the delimiter for ':', it no longer works, and if i put
> sep=',|:' it does not work either. In the end I need to plot the x,y
> values and i will need some of the info in the rows above like the gain to
> manipulate the y data. If you have any tips for me I would be very
> grateful!
Rather than forcing both blocks into the same data structure I would read
the header with the "key: value" lines into a separate object.
If the header and the X,Y pairs are separated by an empty line read until
that and then feed the file object to pandas.read_csv() to read those pairs:
import itertools
import pandas as pd
def header(f):
"""Pass on lines from f; stop at the first whitespace-only line.
"""
return itertools.takewhile(str.strip, f)
def pairs(lines, sep=":"):
"""Split lines into (key, value) pairs.
Remove leading/trailing whitespace from value.
"""
for line in lines:
key, value = line.split(sep, 1)
yield key, value.strip()
with open("data.txt") as f:
metadata = dict(pairs(header(f)))
df = pd.read_csv(f)
print(metadata)
print(df)
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