How to copy a column from a file to another empty file?-CodePudding

I am trying to copy a whole specifit column from a csv file to an empty csv file. My code is as follows.

import pandas as pd
#path_1.csv is the original csv file having the contents I want to copy
src_wb = pd.read_csv(r"path_1.csv")
#path_2.csv is an empty csv file
dest_wb = pd.read_csv(r'path_2.csv')

#Getting the column named "Desc" from the original file
src_sheet = material_library_read["Desc"]
#Getting the first column in the empty file
dest_sheet = dest_wb.iloc[:, 0]

#Inserting the column named "Desc" in path_1.csv into the first column in path_2.csv
dest_wb.insert(0, src_sheet)

#Saving path_2.csv after the copy complete.
dest_sheet.save

However, it keeps showing the error of "No columns to parse from file (which means path_2.csv)". The path_2.csv is an empty file. Why does it have such an error? Please help me finding the bug.

CodePudding user response：

If your csv is empty, then evidently it has no columns, which is why you get the error message. You seem to expect a quasi-empty DataFrame to be generated from dest_wb = pd.read_csv(r'path_2.csv'), but an empty df of course wouldn't have a first column either (dest_sheet = dest_wb.iloc[:, 0]).

In general, the key words used for the variables are rather confusing here. E.g. src_wb = pd.read_csv(r"path_1.csv"), why wb, when we're dealing with a csv read into a df? Similarly, dest_sheet = dest_wb.iloc[:, 0]; why sheet if you want to capture a column?

I'm not sure how this line is supposed to execute: src_sheet = material_library_read["Desc"].

Here's a bit of generic python code to open a src_csv, select 1 column and save it to another csv:

import pandas as pd

file_source = "source.csv"
file_dest = "dest.csv"

df = pd.read_csv(file_source)

#'column1' being the name of your column 
series_col = df.loc[:,'test1'] 

# series to csv as column (without index) and saves csv
series_col.to_csv(file_dest, index=False)