Using the csv-parser to get all the values of a specific column

[CleanHit]

Is there a way to iterate over the values of a specific column using a column name (string)? I've searched the documentation but didn't find a clear answer or an example to my question.

[vincentlaucsb]

Here's an example for printing the values of a specific column. I agree the documentation is a work in progress.

CSVReader reader("my_file.csv");

for (auto& row: reader) {
    std::cout << row["column_name"].get<>() << std::endl;
}

The documentation for the CSVRow object (auto& row) here (https://vincentlaucsb.github.io/csv-parser/classcsv_1_1CSVRow.html) describes the indexing and value retrieval methods.

[CleanHit]

Thanks for the fast reply, I actually saw that yesterday in the documentation and did try it like you wrote, but my IDE gave me some syntax error. Today it worked without any errors, maybe I just needed to restart my IDE....

This brings me to another question. Is this there a more package native way to iterate over each item of some column and being able to change their values? Rather than using this:

vector<double_t> pickupLongitude;
for (csv::CSVRow &row: reader) {
    
    pickupLongitude.push_back(row["Pickup_longitude"].get<double_t>());
}

for (auto &item : pickupLongitude){
    
    \\ Do something with item
}

If I understood it correctly I can iterate over the items with csv::SCVField, but I can't change their value with it. Am I wrong?

[vincentlaucsb]

The CSVReader was designed/optimized for reading values. If you want to modify the values, I would just have some custom logic populate another std::vector like you are doing right now.

However it is still possible to copy a CSVRow to a std::vector<std::string> by typing

std::vector<std::string>(row)

which you might find helpful.

The reason why you can't modify values is because CSVFields are just thin wrappers over string_views. Of course I could implement some feature to modify the original string, but that'd be very inefficient. It's probably a lot cheaper to just copy what you need and modify that. Previous versions of the CSVReader spit out rows as std::vector<std::string>, but those implementations were 30% slower.

[CleanHit]

Thanks and good to know.