Question

我一直坚持这个问题，我希望有人可以提供帮助。我试图遍历一个名为transcripts_test.csv的csv文件中的列[1]，并且对于[1]中的每个字符串，我在另一个名为coors_test.csv的csv文件中创建的名为OCR_dict的字典中匹配相同的字符串。

transcripts_test.csv包含：

ENST00000347869,chr3,50126341,50156454,1    
ENST00000452166,chr14,21679063,21737583,2  
ENST00000452166,chr14,21679063,21737583,2

coors_test.csv包含：

chr3,141030221,141031065,Valid_10009,1000,+  
chr6,141030221,141031065,Valid_10005,1000,+  
chr14,141047080,141047610,Valid_10006,1000,+

这是我的代码：

import csv

with open('coors_test.csv', mode='r') as coors_infile:
    coors_reader = csv.reader(coors_infile)
    for row in coors_reader:
            chromo = row[0]
            start = row[1]
            end = row[2]
            coordinates_list = [chromo,start,end]   
            OCR_dict = {row[3]:coordinates_list}
            for keys,values in OCR_dict.items():
                OCR_chromosome = values[0]
    with open('transcripts_test.csv', mode='r') as transcripts_infile:
        transcripts_reader = csv.reader(transcripts_infile)
        for row in transcripts_reader:
            transcript_chromosome = row[1]
            if transcript_chromosome == OCR_chromosome:
                print(transcript_chromosome, keys, OCR_chromosome)

当我执行上面的代码时，我得到的输出是：

chr14 Valid_10006 chr14  
chr14 Valid_10006 chr14

我正在寻找的输出是：

chr3 Valid_10009 chr3  
chr14 Valid_10006 chr14  
chr14 Valid_10006 chr14

为什么我的代码不匹配并打印chr3 Valid_10009 chr3？任何帮助将不胜感激。谢谢！

Answer 1

这不是你想要的：

        coordinates_list = [chromo,start,end]   
        OCR_dict = {row[3]:coordinates_list}
        for keys,values in OCR_dict.items():
            OCR_chromosome = values[0]

它在每次迭代中创建一个 new dict，并且dict只有一个键。然后循环遍历那一项并更改局部变量...

你想要的可能更像是这样：

from collections import defaultdict
OCR_dict = defaultdict(list)

with open('coors_test.csv', mode='r') as coors_infile:
    coors_reader = csv.reader(coors_infile)
    for row in coors_reader:
        chromo = row[0]
        start = row[1]
        end = row[2] 
        # OCR_dict is a mapping `chromo -> [(start,end), (start,end), ...]`
        OCR_dict[chromo].append((start,end))

with open('transcripts_test.csv', mode='r') as transcripts_infile:
    transcripts_reader = csv.reader(transcripts_infile)
    for row in transcripts_reader:
        transcript_chromosome = row[1]
        # look that chromosome up in the dict and print it if it exists
        if transcript_chromosome in OCR_dict:
            print(transcript_chromosome, OCR_dict[transcript_chromosome])

Answer 2

OCR_chromosome设置为遇到的chromo的最后一个值。换句话说，OCR_chromosome将是coors_test.csv最后一行中的第一个值。 chr14将是唯一可以匹配的值。我不确定你到底想要什么，但这应该产生你正在寻找的chromo值：

import csv

chromos = set()
with open('coors_test.csv', mode='r') as coors_infile:
    for row in csv.reader(coors_infile):
            chromo = row[0]
            chromos.add(chromo)
    with open('transcripts_test.csv', mode='r') as transcripts_infile:
        for row in csv.reader(transcripts_infile):
            transcript_chromosome = row[1]
            if transcript_chromosome in chromos:
                print transcript_chromosome

令人费解的字典匹配问题

2 个答案: