How to code the exception for a column in excel using pandas?

Sample data:

|   | Status                  | Failed | In Progress | Passed | Untested |
|---|-------------------------|--------|-------------|--------|----------|
| 2 | P0 Dry Run - 13/02/18   | 2.0    |             | 143.0  | 5.0      |
| 3 | P1 Test Plan - 06/02/18 | 4.0    |             | 247.0  | 367.0    |
| 4 | P2 Test plan - 03/01/18 | 22.0   | 2.0         | 496.0  | 54.0     |

Code:

msft = pd.read_csv("C:\\Users\\gomathis\\Downloads\\week_071.csv") 
msft = msft[['Passed', 'Failed', 'Blocked', 'In Progress', 'Not_Implemented', 'Not Applicable', 'Clarification Opened', 'Untested']]
msft.to_csv("C:\\Users\\gomathis\\Downloads\\week_072.csv")

Error:

KeyError: "['Blocked'] not in index"

Expected result:

I need an exception for a column which may not be available now but in future it may come. So help me accordingly to solve this.

Use the csv.DictReader.fieldnames attribute, figure out what columns are present in your CSV, and then find the intersection of those.

First, specify the columns you want.

columns = ['Passed', 
           'Failed', 
           'Blocked', 
           'In Progress', 
           'Not_Implemented', 
           'Not Applicable', 
           'Clarification Opened', 
           'Untested']

path = "C:\\Users\\gomathis\\Downloads\\week_071.csv"   # we'll use this later

Next, use the csv.DictReader to read the CSV's headers (this does NOT read the entire file!).

import csv
with open(path, 'r') as f:
    reader = csv.DictReader(f)
    df_columns = reader.fieldnames

Now, find the set intersection, and pass it to usecols in pd.read_csv:

df = pd.read_csv(path, usecols=set(columns).intersection(df_columns))

Finally, to fill in missing columns, take the set difference and call df.assign:

df = df.assign(**dict.fromkeys(set(columns).difference(df_columns), np.nan))