Mike Jones - 8 months ago 40

Python Question

My current code looks for this type of data:

`AHR2,231,123,5,12,51`

GPS,12,312,512,35,12

AHR2,13,125,125123,152,12

CMD,123,123,5,123,51,12

PRAM,1231,CM,12

PRAM,12345,DM,14

AND SO ON

Here is how I am doing it right now:

`import csv`

import matplotlib.pyplot as plt

AHR2 = []

CM = []

with open('data2.csv', 'r') as csvfile:

content = csv.reader(csvfile, delimiter=',')

for row in content:

if 'AHR2' == row[0]:

AHR2.append([row[0]] + list(map(float, row[1:])))

AHR2 = list(zip(*AHR2))

ax.plot(AHR2[1], AHR2[5], label='AHR2 Alt', color = 'red')

This is working fine, except when I am trying to parse the PRAM data part. As you can see there is more than 1 PRAM with different values (CM,DM) I am only interested in the ones that have CM. I have tried this but it gave me an index error.

`if 'CM' == row[2]:`

CM.append([row[0]] + list(map(float, row[1:])))

Is there a way for me to look between the rows and pull the entire row like I am doing above?

Answer

I would really suggest using pandas for this type of work, it will save you a lot of headaches. Your data is a bit messy since it doesn't have a constant number of columns per row, one way to deal with this is discussed here.

Something like this should work

```
import pandas as pd
MAX_COLS_PER_ROW = 7
my_cols = range(0, MAX_COLS_PER_ROW)
df = pd.read_csv('test.csv', names=my_cols)
df
Out[1]:
0 1 2 3 4 5 6
0 AHR2 231 123 5 12.0 51.0 NaN
1 GPS 12 312 512 35.0 12.0 NaN
2 AHR2 13 125 125123 152.0 12.0 NaN
3 CMD 123 123 5 123.0 51.0 12.0
4 PRAM 1231 CM 12 NaN NaN NaN
5 PRAM 12345 DM 14 NaN NaN NaN
```

Then filtering can easily be done with something like

```
(df.loc[:,0] == "PRAM") & (df.loc[:,2] == "CM")
Out[2]:
0 False
1 False
2 False
3 False
4 True
5 False
dtype: bool
df.loc[(df.loc[:,0] == "PRAM") & (df.loc[:,2] == "CM"), :]
Out[3]:
0 1 2 3 4 5 6
4 PRAM 1231 CM 12 NaN NaN NaN
```

I'll leave the plotting to you since the question seems more to do with filtering the data and I am slightly confused on the exact end goal.

Source (Stackoverflow)