file-io

问题 I need to read a big file by reading at most N lines at a time, until EOF. What is the most effective way of doing it in Python? Something like: with open(filename, 'r') as infile: while not EOF: lines = [get next N lines] process(lines) 回答1: One solution would be a list comprehension and the slice operator: with open(filename, 'r') as infile: lines = [line for line in infile][:N] After this lines is tuple of lines. However, this would load the complete file into memory. If you don't want

问题 I need to read a big file by reading at most N lines at a time, until EOF. What is the most effective way of doing it in Python? Something like: with open(filename, 'r') as infile: while not EOF: lines = [get next N lines] process(lines) 回答1: One solution would be a list comprehension and the slice operator: with open(filename, 'r') as infile: lines = [line for line in infile][:N] After this lines is tuple of lines. However, this would load the complete file into memory. If you don't want

问题 I'm working with MATLAB for few days and I'm having difficulties to import a CSV-file to a matrix. My problem is that my CSV-file contains almost only Strings and some integer values, so that csvread() doesn't work. csvread() only gets along with integer values. How can I store my strings in some kind of a 2-dimensional array to have free access to each element? Here's a sample CSV for my needs: 04;abc;def;ghj;klm;;;;; ;;;;;Test;text;0xFF;; ;;;;;asdfhsdf;dsafdsag;0x0F0F;; The main thing are

问题 I'm working with MATLAB for few days and I'm having difficulties to import a CSV-file to a matrix. My problem is that my CSV-file contains almost only Strings and some integer values, so that csvread() doesn't work. csvread() only gets along with integer values. How can I store my strings in some kind of a 2-dimensional array to have free access to each element? Here's a sample CSV for my needs: 04;abc;def;ghj;klm;;;;; ;;;;;Test;text;0xFF;; ;;;;;asdfhsdf;dsafdsag;0x0F0F;; The main thing are

问题 Hi I am trying to take the data from a json file and insert and id then perform POST REST. my file data.json has: { 'name':'myname' } and I would like to add an id so that the json data looks like: { 'id': 134, 'name': 'myname' } So I tried: import json f = open("data.json","r") data = f.read() jsonObj = json.loads(data) I can't get to load the json format file. What should I do so that I can convert the json file into json object and add another id value. 回答1: Set item using data['id'] = ...

问题 How do I get Perl to read the contents of a given directory into an array? Backticks can do it, but is there some method using 'scandir' or a similar term? 回答1: opendir(D, "/path/to/directory") || die "Can't open directory: $!\n"; while (my $f = readdir(D)) { print "\$f = $f\n"; } closedir(D); EDIT: Oh, sorry, missed the "into an array" part: my $d = shift; opendir(D, "$d") || die "Can't open directory $d: $!\n"; my @list = readdir(D); closedir(D); foreach my $f (@list) { print "\$f = $f\n";

问题 In Java web application, Suppose if I want to get the InputStream of an XML file, which is placed in the CLASSPATH (i.e. inside the sources folder), how do I do it? 回答1: ClassLoader.getResourceAsStream(). As stated in the comment below, if you are in a multi- ClassLoader environment (such as unit testing, webapps, etc.) you may need to use Thread.currentThread().getContextClassLoader() . See http://stackoverflow.com/questions/2308188/getresourceasstream-vs-fileinputstream/2308388

问题 In Java web application, Suppose if I want to get the InputStream of an XML file, which is placed in the CLASSPATH (i.e. inside the sources folder), how do I do it? 回答1: ClassLoader.getResourceAsStream(). As stated in the comment below, if you are in a multi- ClassLoader environment (such as unit testing, webapps, etc.) you may need to use Thread.currentThread().getContextClassLoader() . See http://stackoverflow.com/questions/2308188/getresourceasstream-vs-fileinputstream/2308388

问题 What are the elegant and effective ways to count the frequency of each "english" word in a file? 回答1: First of all, I define letter_only std::locale so as to ignore punctuations coming from the stream, and to read only valid "english" letters from the input stream. That way, the stream will treat the words "ways" , "ways." and "ways!" as just the same word "ways" , because the stream will ignore punctuations like "." and "!" . struct letter_only: std::ctype<char> { letter_only(): std::ctype

问题 What are the elegant and effective ways to count the frequency of each "english" word in a file? 回答1: First of all, I define letter_only std::locale so as to ignore punctuations coming from the stream, and to read only valid "english" letters from the input stream. That way, the stream will treat the words "ways" , "ways." and "ways!" as just the same word "ways" , because the stream will ignore punctuations like "." and "!" . struct letter_only: std::ctype<char> { letter_only(): std::ctype