python - 匹配 CSV 中的两列；如果相等，则将值从一个 CSV 复制到另一个 CSV

Question

我有两个 CSV，其中包含基本相同的信息；不幸的是，一个 CSV 缺少多个值。

我的第一个 CSV 的格式为:

url,urlid,boilerplate,label

第二个是:

url, rank

我想将 URL 值相等的行上的排名值从第一个 CSV 复制到第二个 CSV 中。

我怎样才能做到这一点？

Answer 1

# create dict from first csv, with url as key
with open("first.csv", "r") as f:
    first = {rows[0]: rows[1:] for rows in list(csv.reader(f))}

# compare second csv and append rank
with open("second.csv", "r") as f:
    for row in csv.reader(f):
        if row[0] in first: # row[0] = url
            first[row[0]].append(row[1]) # row[1] = rank

# convert dict back to list
merged = [(k,) + tuple(v) for k, v in first.items()]

# write list to output csv
with open("output.csv", "w") as f:
    csv.writer(f).writerows(merged)