数组中的 lambda 找不到变量值

Question

i started in python a little while ago i need your help again, i have a csv file with cached data, and i use a for to go through the data filters and save the filtered data in an array as the example

filters = ['LMS', 'atx', 'arx-dsd']
search_result = []
cached_file = open("teste.csv", "r")

search_result.append(cached_file.readline())
for words in filters:
   print(words)
   if_find = [x for x in cached_file if words in x]
   print(if_find)
   if if_find:
   search_result.extend(if_find)

output:

LMS
[us-east-1a,windows,running,x86_64,IBM,LMS]
ATX
[]
arx-dsd
[]

doesn't find the rest of the results, just the first one in the array, if you do a separate search it finds all the results

i believe my lambda is incorrect so the wrong result

Answer 1

@stovfl already provided the answer for you issue: you can't read multiple times from a file object ,

to fix this you can store your file lines in a variable:

with open("teste.csv", "r") as f:
    cached_file = f.readlines()

Answer 2

First the if_find declaration is not a lambda function but rather a list comprehension try the code below if it suits your needs.

 filters = ['LMS','atx','arx-dsd']
 search_result =[]

 # replace search_result.append(cached_file.readline()) with the following..
 # open csv file and create a list of strings using split
 with open('test.csv','r') as f:
    data = f.readline().strip().split(',')

 #loop through the data which is list of strings
 for i in data:
     print(i)
     if i in filters:    #check if string match in filters
         search_result.append(i)

 print(search_result)

Output:

['LMS']