Replace list of sub-lists in single quotes (seperated with comma)

Question

Using Python3.x, I have a piece of code which generates X with list of sub-lists in single quotes separated by commas...need to print lines Y with replaced values from X.

X = ['sequence, A, 1, 2, 3', 
     'sequence, B, 10, 20, 30', 
     'sequence, C, 100, 200, 300']

Y = ['VEQ','1','map','2','cap',]

Expected output

'VEQ','1','A','2','1'
'VEQ','1','B','2','10'
'VEQ','1','C','2','100'

Y[field3-map] replaced with X[field2], Y[field5-cap] replaced with X[field3], other fields of Y will remain same.

I have already tried to modify below reference code according to my requirement, but it didn't work.

# helper function to find elements  
def find_sub_idx(test_list, repl_list, start = 0): 
    length = len(repl_list) 
    for idx in range(start, len(test_list)): 
        if test_list[idx : idx + length] == repl_list: 
            return idx, idx + length 

# helper function to perform final task 
def replace_sub(test_list, repl_list, new_list): 
    length = len(new_list) 
    idx = 0
    for start, end in iter(lambda: find_sub_idx(test_list, repl_list, idx), None): 
        test_list[start : end] = new_list 
        idx = start + length

what does mean *append of Y:*? post an explicit expected result — RomanPerekhrest, Oct 29 '19 at 07:41

score 1 · Answer 1 · answered Oct 29 '19 at 08:17

Here's something simple and memory efficient (due to lazy evaluation of map), I'm printing the results, hence only one copy of Y is needed and can be overwritten:

X = ['sequence, A, 1, 2, 3', 
     'sequence, B, 10, 20, 30', 
     'sequence, C, 100, 200, 300']

Y = ['VEQ','1','map','2','cap',]
retval = Y[:]

for x in map(lambda x: str.split(x, ','), X):
    retval[2] = x[1]
    retval[4] = x[2]
    print(retval)

If you want to store the values somewhere, you'll need to have a separate copy of Y each time:

X = ['sequence, A, 1, 2, 3', 
     'sequence, B, 10, 20, 30', 
     'sequence, C, 100, 200, 300']

Y = ['VEQ','1','map','2','cap',]

my_list = []

for x in map(lambda x: str.split(x, ','), X):
    retval = Y[:]
    retval[2] = x[1]
    retval[4] = x[2]
    my_list.append(retval)

score 0 · Accepted Answer · answered Oct 29 '19 at 08:02

Not sure if this is what you want but here goes:

X = ['sequence, A, 1, 2, 3', 
     'sequence, B, 10, 20, 30', 
     'sequence, C, 100, 200, 300']

Y = ['VEQ','1','map','2','cap',]

def replace(X,Y,position_list):
    result = []
    for x in X:
        x = x.split(',')
        x = [t.strip() for t in x]
        temp = Y.copy()
        for pos in position_list:
            temp[pos[0] - 1] = x[pos[1] - 1]
        result.append(temp)
    return result

replace(X,Y,[(3,2),(5,3)])

Output:

[['VEQ', '1', 'A', '2', '1'],
 ['VEQ', '1', 'B', '2', '10'],
 ['VEQ', '1', 'C', '2', '100']]

Here position_list is a list of tuple of (Y_pos,X_pos) you want to replace, for example (3,2) means replacing third values of Y with second values of X

thanks. really awesome.. it works.. may i know how to split those lists into lines,, i tried P = replace(X,Y,[(3,2),(5,3)]) P = P.split(',') print(P) but fails as P (list) has no split member — Maria628, Oct 29 '19 at 08:16
Do you want to convert those lists back to string like `'VEQ, 1, A, 2, 1'`? If so, you can try: `P = [', '.join(item) for item in P]` — ExplodingGayFish, Oct 29 '19 at 08:21

Replace list of sub-lists in single quotes (seperated with comma)

2 Answers2