[英]writing a file to a list of tuples
我正在尝试读取文件并将其内容写入元组列表。 每个元组的长度是2,列表的长度是可变的,具体取决于我们从哪个文件中读取。 每个元组应表示x,y平面中的一个点,第一个值为x坐标,第二个为y。 我遇到的问题是,我相信for循环是执行此操作的最佳方法,但是文件的第一行是一个单个值,表示文件中有多少个点,根本不应该将其包括在最终列表中。
def readDataPts(filename):
"""Reads data from an input file and returns a list of tuples
[(x0,y0), (x1, y1), ...]
"""
file = open(filename, 'r')
lines = file.readlines()
listPts = []
for line in lines:
for ptx, pty in line:
x = (ptx, pty)
listPts.append(x)
return listPts
输入的示例是:
10
96571
45734
174416
357259
88 97
188495
348443
301503
719177
182237
输出应为:
[(96, 571), (45, 734), (174, 416), (357, 259), (88, 97).....]
有没有办法从第二行开始for循环? 还是有更简单的方法来解决这个问题?
谢谢
您可以在文件对象上调用next来跳过第一行并从第二行开始,然后拆分每一行并调用元组,或者让csv.reader解析每一行并映射到元组:
分裂:
with open("in.txt") as f:
next(f) # skip first line
arr = [tuple(line.split()) for line in f]
print(arr)
csv库:
import csv
with open("in.txt") as f:
next(f) # skip first line
arr = list(map(tuple, csv.reader(f,delimiter=" ")))
print(arr)
两者都将返回:
[('96', '571'), ('45', '734'), ('174', '416'), ('357', '259'), ('88', '97'), ('188', '495'), ('348', '443'), ('301', '503'), ('719', '177'), ('182', '237')]
如果您想要整数:
with open("in.txt") as f:
next(f) # skip first line
arr = [tuple(map(int, line.split())) for line in f]
print(arr)
和csv.reader:
import csv
with open("in.txt") as f:
next(f) # skip first line
arr = [tuple(map(int,row) for row in csv.reader(f,delimiter=" "))]
print(arr)
这会给你:
[(96, 571), (45, 734), (174, 416), (357, 259), (88, 97), (188, 495), (348, 443), (301, 503), (719, 177), (182, 237
您可以使用.split()
从每行中创建元组并检查长度:
def readDataPts(filename):
listPts = []
with open(filename, 'r') as f:
for line in f:
numbers = line.split()
if len(numbers) == 2:
listPts.append(map(int, numbers))
return listPts
您可以使用tell循环仅对lines [1:]进行迭代,这将跳过第一行并使用其余所有行。
def readDataPts(filename):
"""Reads data from an input file and returns a list of tuples
[(x0,y0), (x1, y1), ...]
"""
file = open(filename, 'r')
lines = file.readlines()
listPts = []
for line in lines[1:]:
for ptx, pty in line:
x = (ptx, pty)
listPts.append(x)
return listPts
只是另一个想法。
with open('in.txt') as f:
nums = map(int, f.read().split())
print zip(nums[1::2], nums[2::2])
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