[Tutor] Extract Field from List

[Peter Otten]

On 08/08/2021 15:48, Stephen P. Molnar wrote:
> I have hit a roadblock in a Python script I have been developing to 
> process a large number of text files of fixed format.
> 
> I have a list of names of chemicals, which I can read into a list.csv:
> 
> CaffeicAcid,Cannflavin-A,Cannflavin-B,Cannflavin-C,Diosmetin,Echinacoside,Hesperetin,L-CichoricAcid 
> 
> 
> My code is;
> 
> import csv
> 
> with open("Ligand.list_r.txt", newline='') as csvfile:
>      rows = csv.reader(csvfile, delimiter = ',')
>      data = []
>      for rows in rows:
>          data.append(rows)
> 
> print(data)
> 
> This results in:
> 
> [['CaffeicAcid\tCannflavin-A\tCannflavin-B\tCannflavin-C\tDiosmetin\tEchinacoside\tHesperetin\tL-CichoricAcid']] 
> 
> 
> when run.
> 
> What I need to do is iterate through the list and generate names of the 
> format of chemicalname+'.i.log'.
> 
> This is where I can seem to hit a show stopper. How do I extract fields 
> form the list generated by the script that works? What am I missing?


(1) Your CSV is tab-delimited
(2) There is only one row

Try

with open(...) as csvfile:
     rows = csv.reader(csvfile, delimiter='\t')
     [data] = rows

This ensures that there is only one row so that no data can be lost 
accidentally. Note that data will be a tuple; convert it if necessary.