如何使用python 3.7.5查找其他CSV文件中不存在的行

Question

我有一个文件ua.csv，它有2行，还有一个文件pr.csv，它有4行。我想知道pr.csv和ua.csv中没有的行是什么，需要在输出中有pr.csv中的额外行数。

ua.csv

Name|Address|City|Country|Pincode
Jim Smith|123 Any Street|Boston|US|02134 
Jane Lee|248 Another St.|Boston|US|02130 

pr.csv

Name|Address|City|Country|Pincode
Jim Smith|123 Any Street|Boston|US|02134 
Smoet|coffee shop|finland|Europe|3453335
Jane Lee|248 Another St.|Boston|US|02130 
Jack|long street|malasiya|Asia|585858

预期产出如下：

pr.csv has 2 rows extra

Name|Address|City|Country|Pincode
Smoet|coffee shop|finland|Europe|3453335
Jack|long street|malasiya|Asia|585858

Answer 1

我想您可以使用set数据结构：

ua_set = set()
pr_set = set()

# Code to populate the sets reading the csv files (use the `add` method of sets)
...

# Find the difference
diff = pr_set.difference(ua_set)

print(f"pr.csv has {len(diff)} rows extra")

# It would be better to not hardcode the name of the columns in the output 
# but getting the info depends on the package you use to read csv files
print("Name|Address|City|Country|Pincode")  

for row in diff:
    print(row)

使用pandas模块的更好解决方案：

import pandas as pd

df_ua = pd.read_csv("ua.scv") # Must modify path to ua.csv
df_pr = pd.read_csv("pr.csv") # Must modify path to pr.csv

df_diff = df_pr.merge(df_ua, how="outer", indicator=True).loc[lambda x: x["_merge"] == "left_only"].drop("_merge", axis=1)

print(f"pr.csv has {len(df_diff)} rows extra")

print(df_diff)

Answer 2

import csv
ua_dic={}
with open('ua.csv') as ua:
  data=csv.reader(ua,delimiter=',')

  for i in data:
    if str(i) not in ua_dic:
        ua_dic[str(i)]=1

output=[]
with open('pr.csv') as pr:
  data=csv.reader(pr,delimiter=',')

  for j in data:
    if str(j) not in ua_dic:
        output.append(j)

  print(output)