Skip concatenating the first value-CodePudding

My question is fairly straight forward.

I am trying to concatenate a string with a returned value in a loop. I don't want to add the text to the first occurrence, but to the rest.

Here is the sample code:

list_of_tables = {'k1': 'v1:v2',
'k2':'v3:v4',
'k3':'v5:v6',
'k4':'v7:v8',
'k5':None }

def gen_stmt(val1_name, val2_name):
    
    return 'some text '  val1_name   ': '  val2_name

stmt = ''
for k,v in list_of_tables.items():
    if v:
        pair_val = v.split(':') 
        fin_value  = 'text I need to concat'   gen_stmt(*pair_val)
    return fin_value

What I need 'text I need to concat' for all the values of k2,k3,k4 and I need to run gen_stmt function for all the keys k1 ...k5

How can I concatenate all the values except the first value?

What I want the output to be

some text v1 : v2 text I need to concat some text v3 : v4 text I need to concat some text v5 : v6 text I need to concat some text v7 : v8

CodePudding user response：

I would break this out a bit more.

Make a loop that can transform each item into a string and add it to a list.

Then join the final list using whatever delimiter you need.

Try something like this:

string_values = []
for value in list_of_tables.values():
    if value:
        val1, val2 = value.split(':')
        string_value = gen_stmt(val1, val2)
        string_values.append(string_value)


print(' text I need to concat '.join(string_values))

To skip the first value, you can turn the values object into a list, and then slice off the first value:

And a one liner just for kicks:

print(' text I need to concat '.join(
    gen_stmt(*value.split(':'))
    for value in list_of_tables.values()
    if value
))

CodePudding user response：

You can also pass a if-else statement which will filter first value from other elements of list. my suggested code is like this.

list_of_tables = {'k1': 'v1:v2',
'k2':'v3:v4',
'k3':'v5:v6',
'k4':'v7:v8',
'k5':None }
def gen_stmt(val1_name, val2_name):
    
    return 'some text '  val1_name   ':'  val2_name

fin_value = ''
i = 0
for k,v in list_of_tables.items():
    if i == 0:
        pair_val = v.split(':')
        fin_value = gen_stmt(*pair_val)   " "          
    elif v:
        pair_val = v.split(':')
        fin_value  = 'text I need to concat'   gen_stmt(*pair_val)
    i  =1

print(fin_value)

I think this very simple method but yes some extra line here added which make your code little bit long.