我使用for循环来读取文件,但我只想读取特定的行,比如第26行和第30行。是否有任何内置功能来实现这一点?
当前回答
def getitems(iterable, items):
items = list(items) # get a list from any iterable and make our own copy
# since we modify it
if items:
items.sort()
for n, v in enumerate(iterable):
if n == items[0]:
yield v
items.pop(0)
if not items:
break
print list(getitems(open("/usr/share/dict/words"), [25, 29]))
# ['Abelson\n', 'Abernathy\n']
# note that index 25 is the 26th item
其他回答
为了提供另一种解决方案:
import linecache
linecache.getline('Sample.txt', Number_of_Line)
我希望这是快速和简单的:)
您可以使用一种最简单的逻辑将字符串拆分为数组或List。
f = open('filepath')
r = f.read()
s = r.split("\n")
n = [linenumber1, linenumber2] # [26, 29] in your
#case
for x in n:
print(s[x-1])
f.close()
如果你想看第7行
line = open("file.txt", "r").readlines()[7]
从某一行读出:
n = 4 # for reading from 5th line
with open("write.txt",'r') as t:
for i,line in enumerate(t):
if i >= n: # i == n-1 for nth line
print(line)
不要使用阅读线!
我的解决方案是:
with open(filename) as f:
specify = [26, 30]
results = list(
map(lambda line: line[1],
filter(lambda line: line[0] in specify,
enumerate(f))
)
)
对6.5G文件进行如下测试:
import time
filename = 'a.txt'
start = time.time()
with open(filename, 'w') as f:
for i in range(10_000_000):
f.write(f'{str(i)*100}\n')
end1 = time.time()
with open(filename) as f:
specify = [26, 30]
results = list(
map(lambda line: line[1],
filter(lambda line: line[0] in specify,
enumerate(f))
)
)
end2 = time.time()
print(f'write time: {end1-start}')
print(f'read time: {end2-end1}')
# write time: 14.38945460319519
# read time: 8.380386352539062
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