[英]How can I add a column to a CSV file?
我有以下CSV文件:
header 1, header 2, header 3
summin 1, summin 2, summin 3
summin 4, summin 5, summin 6
如何使用CSV類附加一列數據,因此結果如下所示:
header 1, header 2, header 3, header 4
summin 1, summin 2, summin 3, new value 1
summin 4, summin 5, summin 6, new value 2
當CSV文件包含標題時,您可以訪問和操作列:
require "csv"
table = CSV.read("test.csv", {headers: true, col_sep: ", "})
# change col 3 in one go, (or add a new one: table["header_4"] = ['summin 3','summin 6'] ):
table["header_3"] = ['summin 3','summin 6']
# Add another col, row by row:
table.each do |row|
row["header_4"] = rand(9)
end
# write to file
CSV.open("test2.csv", "w") do |f|
f << table.headers
table.each{|row| f << row}
end
我能想出的唯一使用CSV類的方法是讀取文件,然后用額外的列重寫數據。 讓我們生成您的CSV數據:
csv = CSV.generate do |csv|
csv << ['header 1', 'header 2', 'header 3']
csv << ['summin 1', 'summin 2', 'summin 3']
csv << ['summin 4', 'summin 5', 'summin 6']
end
我們可以使用CSV.parse
迭代CSV.parse
(盡管您可能希望使用CSV.foreach
如果您正在讀取文件),並在塊中創建新的CSV數據:
# Values for new column (including header)
new_values = ['header 4', 'new value 1', 'new value 2']
i = 0
CSV.parse(csv) do |row|
new_csv = CSV.generate do |new_csv|
new_csv << row + [new_values[i]]
i += 1
end
puts new_csv
end
以上結果是您的最終CSV:
header 1,header 2,header 3,header 4
summin 1,summin 2,summin 3,new value 1
summin 4,summin 5,summin 6,new value 2
請注意,在寫入文件時,您需要使用CSV.open
,而不是CSV.generate
。
require "csv"
column_to_add=["new value 1","new value 1"]
CSV.open(/Folder/new_file_name.csv, "wb") do |csv|
csv << ["header 1", "header 2", "header 3", "header 4"]
CSV.foreach(/Folder/OriginalFile.csv, headers: true) do |row,index|
csv << [row[1], row[2] , row[3] , column_to_add[index]]
end
end
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