python - 如何比较两个csv文件？

Question

我有一个csv file1，就像

FLAGSTAFF   AZ  50244.67    5.02    KA1_Podium_Garage_S
FLAGSTAFF   AZ  33752.13    3.38    KA1_Podium_Garage_S
FLAGSTAFF   AZ  11965.5      1.2    KA1_Podium_Garage_S
FLAGSTAFF   AZ  3966.48      0.4    KA1_Podium_Garage_S
SEATTLE     WA  12646.9      1.26   KA1_Podium_Garage_S
SEATTLE     WA  225053.92   22.51   KA1_Podium_Garage_S
SEATTLE     WA  23974.3      2.4    KA1_Podium_Garage_S
SEATTLE     WA  7036.4       0.7    KA1_Podium_Garage_S
SEATTLE     WA  3021.93      0.3    KA1_Podium_Garage_S

我有一个 csv 文件 2，就像 ,

Alabama     AL  1
Alaska      AK  2
Arizona     AZ  4
Arkansas    AR  5
California  CA  6
Colorado    CO  8
Connecticut CT  9
SEATTLE     WA  53

现在我必须将第三列值从 csv file2 附加到 csv file1，通过比较第二列

例如它应该看起来像，

AZ 代码为 4WA代码是53无论 AZ,WA 在我的 csv file1 中哪里，代码都应该附加到一列中

我的输出应该是这样的

FLAGSTAFF   AZ  50244.67    5.02    KA1_Podium_Garage_S 4
FLAGSTAFF   AZ  33752.13    3.38    KA1_Podium_Garage_S 4
FLAGSTAFF   AZ  11965.5      1.2    KA1_Podium_Garage_S 4
FLAGSTAFF   AZ  3966.48      0.4    KA1_Podium_Garage_S 4
SEATTLE     WA  12646.9      1.26   KA1_Podium_Garage_S 53
SEATTLE     WA  225053.92   22.51   KA1_Podium_Garage_S 53
SEATTLE     WA  23974.3      2.4    KA1_Podium_Garage_S 53
SEATTLE     WA  7036.4       0.7    KA1_Podium_Garage_S 53
SEATTLE     WA  3021.93      0.3    KA1_Podium_Garage_S 53

这是我试过的代码，

with open("/home/sumit/Desktop/CSV_FILE1.csv", "r") as f:
    first = {rows[1]: rows[0:] for rows in list(csv.reader(f))}

# compare second csv and append Code
with open("CSVFILE2.csv", "r") as f1:
    for row in csv.reader(f1):
        if row[1] in first:
            first[row[1]].append(row[2])

# 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 f1:
    csv.writer(f1).writerows(merged)

输出越来越像，

AZ  FLAGSTAFF   AZ  44230.4 4.42    KA1_Podium_Garage_S 4
WA  SEATTLE     WA  45329.3 4.53    KA1_Podium_Garage_S 53

Answer 1

此行根据您的第一个文件创建一个基于州缩写的字典。这看起来是错误的，因为字典只能有每个键一次，例如，您有多个带有“AZ”的行。

first = { rows[1]: rows[0:] for rows in list(csv.reader(f)) }

相反，您应该根据第二个文件制作字典:

with open("CSVFILE2.csv", "r") as f1:
    code = { row[1]: row[2] for row in csv.reader(f1) }

然后，遍历您的第一个文件，并将适当的代码附加到每一行。

with open("/home/sumit/Desktop/CSV_FILE1.csv", "r") as f:
    merged = [ row + [code[row[1]]] for row in csv.reader(f) ]

并将合并后的数据写入新文件。

---

row + [code[row[1]]]的解释:

如果行是 ["FLAGSTAFF", "AZ", 50244.67, 5.02, "KA1_Podium_Garage_S"]，则

• row[1] 是 "AZ",
• code[row[1]] 是 code["AZ"] 即 4,
• [code[row[1]]] 是列表 [4]
• 和 row + [code[row[1]] 是列表连接，产生所需的新行值:["FLAGSTAFF", "AZ", 50244.67, 5.02, "KA1_Podium_Garage_S ", 4]