在python中使用readlines？第一次
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Using readlines in python? First time
提问by user1762768
I have a text file with columns of data and I need to turn these columns into individual lists or arrays. This is what I have so far
我有一个包含数据列的文本文件，我需要将这些列转换为单独的列表或数组。这是我到目前为止
f = open('data.txt', 'r')
temp = []
for row in f.readlines():
Data = row.split()
temp.append(float(Data[0]))
When I run this I get IndexError: list index out of range.
当我运行这个时，我得到IndexError: list index out of range.
Snippet of the data below:
以下数据片段：
16 0.2000
17 0.3000
18 0.4000
20 0.5000
21 0.6000
22 0.7000
24 0.8000
25 0.9000
26 1.000
I need the first column, if possible to look like this: Data = [16, 17, 18, 20, 21, 22, 24, 25, 26]
我需要第一列，如果可能的话，看起来像这样：Data = [16, 17, 18, 20, 21, 22, 24, 25, 26]
采纳答案by root
You are getting an empty list Data=[]if you read an empty row. You try to get the first element from the list using Data[0],but because it's an empty list it doesn't have an element at position 0, so you get an IndexError.
Data=[]如果您读取一个空行，您将得到一个空列表。您尝试使用 获取列表中的第一个元素Data[0]，但由于它是一个空列表，因此在位置 0 处没有元素，因此您会得到IndexError.
Data=''.split()
Data[0]
---------------------------------------------------------------------------
IndexError Traceback (most recent call last)
<ipython-input-686-0792b03cbbdf> in <module>()
----> 1 Data[0]
IndexError: list index out of range
This will print out the Dataif IndexErroroccours - you can see yourself that it prints an empty list:
这将打印出Dataif IndexErroroccous - 您可以看到它打印了一个空列表：
f=open('file','r')
temp = []
for row in f.readlines():
Data = row.split()
try:
temp.append(float(Data[0]))
except IndexError:
print Data
You can use the withstatement to open the file, that automatically closes the file after being processed. Also you can loop over the file itself, without using readlines().
您可以使用该with语句打开文件，处理后自动关闭文件。您也可以遍历文件本身，而不使用readlines().
with open(file,'r') as f:
for row in f:
Data = row.split()
try:
print Data[0]
except IndexError:
print 'You have an empty row'
EDIT: You are better of using the csv module:
编辑：您最好使用 csv 模块：
import csv
with open('file.csv', 'rb') as f:
reader = csv.reader(f, delimiter=' ')
print [row[0] for row in reader if len(row)]
>>>
['16', '17', '18', '20', '21', '22', '24', '25', '26']
回答by Inbar Rose
use with for filehandlers.
用于文件处理程序。
with open('path/to/file', 'r') as f:
for line in f:
# code.
you index error comes from trying to access Dataat the [0]location.
which simply means your line was empty.
您的索引错误来自尝试访问Data该[0]位置。这只是意味着您的线路是空的。
you should run a quick check before parsing the line...
您应该在解析该行之前进行快速检查...
if len(Data):
#code
else:
#empty line?
回答by okan kilic
f = open('data.txt', 'r')
temp = []
for row in f.readlines():
items = row.split(',')
temp.append(unicode(items[0]))
I hope that it solves your problem.
我希望它能解决你的问题。
回答by user4730171
def cal(num_list):
x = 1;
z = 0;
while True:
list1 = list(str(x))
list2 = [int(a) for a in list1]
for i in range(len(list2)):
for j in range(10):
if(list2.count(j) > num_list[list2[i]]):
z = 1;
break;
if(z == 1):
save(x);
break;
x = x + 1;
回答by user4816019
#matrix A to B
def show():
global string_final,list_2,tot
index=matrix_1.index(num) # finding index of num
length=n
j=(index)%length # the column positon
i=index/length # the row position
list_1=[]
for a in range(length):
lis=[]
for b in range(length):
lis.append(matrix_1.pop(0)) #pop the first element and append the list
list_1.append(lis)
tot=0
list_2=[]
for a in range(i+1):
for b in range(j+1):
tot=tot+list_1[a][b] # add the numbers
list_2.append(list_1[a][b]) #append to list
if(b!=length):
list_2.append(" ") #append space
list_2.append("\n")
string_final="".join([str(a) for a in list_2]) #list to string
print "matrix B\n",string_final,"\nx: ",str(num),"\nn: ",str(n)+"\ntotal: "+str(tot) # print the result
回答by user4816019
#matrix add zero
def get():
global b_no
num_list=[];
file=open("matrix.txt","r");
for i in file:
b_no=0
if(len(i.split())==1): #check length is 1 or not
n=int(i)#string to int
else:
temp=i.split();
if(len(temp)!=n):
b_no+=1
break
temp=[0]+[int(a) for a in temp]+[0] #add zero at first and last
num_list.append(temp);
zero_list=[]
for i in range(n+2):
zero_list.append(0) #append zero
num_list.insert(0,zero_list)
num_list.insert(n+1,zero_list)
return num_list,n;
回答by kevin
I would avoid using Data[0] or row[0], instead, I would use ''.join(Data) or ''.join(row) to avoid empty list (list index out of range error).
我会避免使用 Data[0] 或 row[0]，相反，我会使用 ''.join(Data) 或 ''.join(row) 来避免空列表（列表索引超出范围错误）。
