entityMap|blocks|key|5b029|text|您必须使用以下命令将字符串拆分为一个值列表split()|type|unstyled|depth|inlineStyleRanges|offset|length|style|CODE|entityRanges|data|ff5re|所以，|eooce|lines+=+text_file.read().split(',')|code-block|syntax|js|22ssl|编辑:我没有意识到这会有这么大的吸引力。这里有一种更惯用的方法。|anmk1|import+csv
with+open('filename.csv',+'r')+as+fd:
++++reader+=+csv.reader(fd)
++++for+row+in+reader:
++++++++#+do+something|javascript^0|L|7|0|0|0|0^^$0|$]|1|@$2|3|4|5|6|7|8|S|9|@$A|T|B|U|C|D]]|E|@]|F|$]]|$2|G|4|H|6|7|8|V|9|@]|E|@]|F|$]]|$2|I|4|J|6|K|8|W|9|@]|E|@]|F|$L|M]]|$2|N|4|O|6|7|8|X|9|@]|E|@]|F|$]]|$2|P|4|Q|6|K|8|Y|9|@]|E|@]|F|$L|R]]]]

You will have to split your string into a list of values using <code>split()</code>
So,
<pre><code>lines = text_file.read().split(',')
</code></pre>
EDIT:
I didn't realise there would be so much traction to this. Here's a more idiomatic approach.
<pre class="lang-py prettyprint-override"><code>import csv
with open('filename.csv', 'r') as fd:
 reader = csv.reader(fd)
 for row in reader:
 # do something
</code></pre>

entityMap|blocks|key|4p53i|text|您还可以使用numpy+loadtxt，如下所示|type|unstyled|depth|inlineStyleRanges|entityRanges|data|7cp8o|from+numpy+import+loadtxt
lines+=+loadtxt("filename.dat",+comments="#",+delimiter=",",+unpack=False)|code-block|syntax|javascript^0|0^^$0|$]|1|@$2|3|4|5|6|7|8|H|9|@]|A|@]|B|$]]|$2|C|4|D|6|E|8|I|9|@]|A|@]|B|$F|G]]]]

You can also use numpy loadtxt like

<pre><code>from numpy import loadtxt
lines = loadtxt("filename.dat", comments="#", delimiter=",", unpack=False)
</code></pre>

entityMap|blocks|key|7n9j0|text|所以你想创建一个列表列表...我们需要从一个空列表开始|type|unstyled|depth|inlineStyleRanges|entityRanges|data|2fque|list_of_lists+=+[]|code-block|syntax|js|5e6dc|接下来，我们逐行读取文件内容|fcofb|with+open('data')+as+f:
++++for+line+in+f:
++++++++inner_list+=+[elt.strip()+for+elt+in+line.split(',')]
++++++++#+in+alternative,+if+you+need+to+use+the+file+content+as+numbers
++++++++#+inner_list+=+[int(elt.strip())+for+elt+in+line.split(',')]
++++++++list_of_lists.append(inner_list)|javascript|9t5i7|一种常见的用例是列数据，但是我们的存储单元是文件的行，我们已经逐个读取了这些行，因此您可能希望转置你的列表。这可以通过下面的习惯用法来实现|crn3h|by_cols+=+zip(*list_of_lists)|3ab1m|另一种常见用法是为每列指定一个名称|6stma|col_names+=+('apples+sold',+'pears+sold',+'apples+revenue',+'pears+revenue')
by_names+=+{}
for+i,+col_name+in+enumerate(col_names):
++++by_names[col_name]+=+by_cols[i]|8hjqo|这样您就可以对同构数据项进行操作|4ed0d|mean_apple_prices+=+[money/fruits+for+money,+fruits+in
+++++++++++++++++++++zip(by_names['apples+revenue'],+by_names['apples_sold'])]|ah6e7|我所写的大部分内容都可以使用csv模块，来自标准库。另一个第三方模块是pandas，这使您可以自动化典型数据分析的大多数方面(但有许多依赖项)。|offset|length|style|CODE|aip4c|更新在Python+2中zip(*list_of_lists)返回一个不同的(转置的)列表列表，在Python+3中，情况已经改变zip(*list_of_lists)返回zip对象这是不可订阅的。|ahm36|如果你需求可以使用的索引访问|d41r0|by_cols+=+list(zip(*list_of_lists))|535dv|这为您提供了两个版本的Python中的列表。|3vro9|另一方面，如果你不需要索引访问，您想要的只是构建一个按列名索引的字典，一个zip对象就可以了……|426jf|file+=+open('some_data.csv')
names+=+get_names(next(file))
columns+=+zip(*((x.strip()+for+x+in+line.split(','))+for+line+in+file)))
d+=+{}
for+name,+column+in+zip(names,+columns):+d[name]+=+column^0|0|0|0|0|0|0|0|0|0|0|E|3|Z|6|0|C|J|1T|J|0|0|0|0|0^^$0|$]|1|@$2|3|4|5|6|7|8|1G|9|@]|A|@]|B|$]]|$2|C|4|D|6|E|8|1H|9|@]|A|@]|B|$F|G]]|$2|H|4|I|6|7|8|1I|9|@]|A|@]|B|$]]|$2|J|4|K|6|E|8|1J|9|@]|A|@]|B|$F|L]]|$2|M|4|N|6|7|8|1K|9|@]|A|@]|B|$]]|$2|O|4|P|6|E|8|1L|9|@]|A|@]|B|$F|G]]|$2|Q|4|R|6|7|8|1M|9|@]|A|@]|B|$]]|$2|S|4|T|6|E|8|1N|9|@]|A|@]|B|$F|L]]|$2|U|4|V|6|7|8|1O|9|@]|A|@]|B|$]]|$2|W|4|X|6|E|8|1P|9|@]|A|@]|B|$F|L]]|$2|Y|4|Z|6|7|8|1Q|9|@$10|1R|11|1S|12|13]|$10|1T|11|1U|12|13]]|A|@]|B|$]]|$2|14|4|15|6|7|8|1V|9|@$10|1W|11|1X|12|13]|$10|1Y|11|1Z|12|13]]|A|@]|B|$]]|$2|16|4|17|6|7|8|20|9|@]|A|@]|B|$]]|$2|18|4|19|6|E|8|21|9|@]|A|@]|B|$F|G]]|$2|1A|4|1B|6|7|8|22|9|@]|A|@]|B|$]]|$2|1C|4|1D|6|7|8|23|9|@]|A|@]|B|$]]|$2|1E|4|1F|6|E|8|24|9|@]|A|@]|B|$F|L]]]]

So you want to create a list of lists... We need to start with an empty list

<pre><code>list_of_lists = []
</code></pre>

next, we read the file content, line by line

<pre><code>with open('data') as f:
 for line in f:
 inner_list = [elt.strip() for elt in line.split(',')]
 # in alternative, if you need to use the file content as numbers
 # inner_list = [int(elt.strip()) for elt in line.split(',')]
 list_of_lists.append(inner_list)
</code></pre>

A common use case is that of columnar data, but our units of storage are the
rows of the file, that we have read one by one, so you may want to transpose
your list of lists. This can be done with the following idiom

<pre><code>by_cols = zip(*list_of_lists)
</code></pre>

Another common use is to give a name to each column

<pre><code>col_names = ('apples sold', 'pears sold', 'apples revenue', 'pears revenue')
by_names = {}
for i, col_name in enumerate(col_names):
 by_names[col_name] = by_cols[i]
</code></pre>

so that you can operate on homogeneous data items

<pre><code> mean_apple_prices = [money/fruits for money, fruits in
 zip(by_names['apples revenue'], by_names['apples_sold'])]
</code></pre>

Most of what I've written can be speeded up using the <code>csv</code> module, from the standard library. Another third party module is <code>pandas</code>, that lets you automate most aspects of a typical data analysis (but has a number of dependencies).

<hr>

Update While in Python 2 <code>zip(*list_of_lists)</code> returns a different (transposed) list of lists, in Python 3 the situation has changed and <code>zip(*list_of_lists)</code> returns a zip object that is not subscriptable.

If you need indexed access you can use

<pre><code>by_cols = list(zip(*list_of_lists))
</code></pre>

that gives you a list of lists in both versions of Python.

On the other hand, if you don't need indexed access and what you want is just to build a dictionary indexed by column names, a zip object is just fine...

<pre><code>file = open('some_data.csv')
names = get_names(next(file))
columns = zip(*((x.strip() for x in line.split(',')) for line in file)))
d = {}
for name, column in zip(names, columns): d[name] = column
</code></pre>

entityMap|0|type|LINK|mutability|MUTABLE|data|url|https://docs.python.org/3.6/library/csv.html|blocks|key|4ngd0|text|这个问题是问如何将文件中的逗号分隔值内容读取到可迭代列表中：|unstyled|depth|inlineStyleRanges|entityRanges|4vm5s|0,0,200,0,53,1,0,255,...,0.|offset|length|style|CODE|6je6t|要做到这一点，最简单的方法是使用csv模块，如下所示：|1jgoq|import+csv
with+open('filename.dat',+newline='')+as+csvfile:
++++spamreader+=+csv.reader(csvfile,+delimiter=',')|code-block|syntax|javascript|fsjuv|现在，您可以轻松地遍历spamreader如下所示：|6dhqv|for+row+in+spamreader:
++++print(',+'.join(row))|4qeuj|请参见**documentation**获取更多示例。^0|0|0|R|0|G|3|0|0|B|A|0|0|3|H|0^^$0|$1|$2|3|4|5|6|$7|8]]]|9|@$A|B|C|D|2|E|F|11|G|@]|H|@]|6|$]]|$A|I|C|J|2|E|F|12|G|@$K|13|L|14|M|N]]|H|@]|6|$]]|$A|O|C|P|2|E|F|15|G|@$K|16|L|17|M|N]]|H|@]|6|$]]|$A|Q|C|R|2|S|F|18|G|@]|H|@]|6|$T|U]]|$A|V|C|W|2|E|F|19|G|@$K|1A|L|1B|M|N]]|H|@]|6|$]]|$A|X|C|Y|2|S|F|1C|G|@]|H|@]|6|$T|U]]|$A|Z|C|10|2|E|F|1D|G|@]|H|@$K|1E|L|1F|A|1G]]|6|$]]]]

This question is asking how to read the comma-separated value contents from a file into an iterable list: 

<code>0,0,200,0,53,1,0,255,...,0.</code>

The easiest way to do this is with the <code>csv</code> module as follows:

<pre><code>import csv
with open('filename.dat', newline='') as csvfile:
 spamreader = csv.reader(csvfile, delimiter=',')
</code></pre>

Now, you can easily iterate over <code>spamreader</code> like this:

<pre><code>for row in spamreader:
 print(', '.join(row))
</code></pre>

See <a href="https://docs.python.org/3.6/library/csv.html" rel="noreferrer">documentation</a> for more examples.

I am trying to read the lines of a text file into a list or array in python. I just need to be able to individually access any item in the list or array after it is created.

The text file is formatted as follows:

<pre><code>0,0,200,0,53,1,0,255,...,0.
</code></pre>

Where the <code>...</code> is above, there actual text file has hundreds or thousands more items.

I'm using the following code to try to read the file into a list:

<pre><code>text_file = open("filename.dat", "r")
lines = text_file.readlines()
print lines
print len(lines)
text_file.close()
</code></pre>

The output I get is:

<pre><code>['0,0,200,0,53,1,0,255,...,0.']
1
</code></pre>

Apparently it is reading the entire file into a list of just one item, rather than a list of individual items. What am I doing wrong?

How to read a text file into a list or an array with Python

数据分析

Python

 我正在尝试将文本文件的行读入python中的列表或数组。我只需要在列表或数组创建后能够单独访问它。 文本文件的格式如下： 0,0,200,0,53,1,0,255,...,0. 其中...如上所述，实际文本文件中有数百或数千个以上的项目。 我使用以下代码尝试将文件读取到列表中： text_file = open("f...

问如何使用Python将文本文件读入列表或数组
EN

社区

活动

资源

关于

腾讯云开发者

热门产品

热门推荐

更多推荐

问如何使用Python将文本文件读入列表或数组EN

社区

活动

资源

关于

腾讯云开发者

热门产品

热门推荐

更多推荐

问如何使用Python将文本文件读入列表或数组
EN