concatenation

问题 I am working with Hadoop 0.20.2 and would like to concatenate two files into one using the -cat shell command if possible (source: http://hadoop.apache.org/common/docs/r0.19.2/hdfs_shell.html) Here is the command I'm submitting (names have been changed): **/path/path/path/hadoop-0.20.2> bin/hadoop fs -cat /user/username/folder/csv1.csv /user/username/folder/csv2.csv > /user/username/folder/outputdirectory/** It returns bash: /user/username/folder/outputdirectory/: No such file or directory I

问题 I am working with Hadoop 0.20.2 and would like to concatenate two files into one using the -cat shell command if possible (source: http://hadoop.apache.org/common/docs/r0.19.2/hdfs_shell.html) Here is the command I'm submitting (names have been changed): **/path/path/path/hadoop-0.20.2> bin/hadoop fs -cat /user/username/folder/csv1.csv /user/username/folder/csv2.csv > /user/username/folder/outputdirectory/** It returns bash: /user/username/folder/outputdirectory/: No such file or directory I

问题 I have a data.frame from this code: my_df = data.frame("read_time" = c("2010-02-15", "2010-02-15", "2010-02-16", "2010-02-16", "2010-02-16", "2010-02-17"), "OD" = c(0.1, 0.2, 0.1, 0.2, 0.4, 0.5) ) which produces this: > my_df read_time OD 1 2010-02-15 0.1 2 2010-02-15 0.2 3 2010-02-16 0.1 4 2010-02-16 0.2 5 2010-02-16 0.4 6 2010-02-17 0.5 I want to average the OD column over each distinct read_time (notice some are replicated others are not) and I also would like to calculate the standard

问题 (Assume that: application start-up time is absolutely critical; my application is started a lot; my application runs in an environment in which importing is slower than usual; many files need to be imported; and compilation to .pyc files is not available.) I would like to concatenate all the Python source files that define a collection of modules into a single new Python source file. I would like the result of importing the new file to be as if I imported one of the original files (which

问题 (Assume that: application start-up time is absolutely critical; my application is started a lot; my application runs in an environment in which importing is slower than usual; many files need to be imported; and compilation to .pyc files is not available.) I would like to concatenate all the Python source files that define a collection of modules into a single new Python source file. I would like the result of importing the new file to be as if I imported one of the original files (which

问题 For example I have two tables. The first table is student while the second table are the courses that the a student is taking. How can I use a select statement so that I can see two columns student and courses so that the courses are separated by commas. Thanks. 回答1: Assuming you're using SQL Server 2005: This should do what you're after - obviously replace fields as you need: For demo purposes, consider the following two table structures: Students( STU_PKEY Int Identity(1,1) Constraint PK

问题 I have the following code: struct simple { simple (int a1, int a2) : member1(a1), member2(a2) {} int member1; int member2; }; std::ofstream &operator << (std::ofstream &f, const simple &obj) { f<<obj.member1<<", "<<obj.member2; return f; } int main(int argc, const char *argv[]) { std::ofstream f("streamout.txt"); simple s(7,5); f << s; //#1 This works f << "label: " << s; //#2 This fails return 0; } I'm trying to understand why #1 works, while there are problems when trying to use the

问题 If I have the table SELECT (Firstname || '-' || Middlename || '-' || Surname) AS example_column FROM example_table This will display Firstname-Middlename-Surname e.g. John--Smith Jane-Anne-Smith The second one (Jane’s) displays correct, however since John doesn’t have a middlename, I want it to ignore the second dash. How could I put a sort of IF Middlename = NULL statement in so that it would just display John-Smith 回答1: Here would be my suggestions: PostgreSQL and other SQL databases where

问题 This is my first time using Grunt and I'd like to have it combine all my js modules, each of which is wrapped in an immediately executing function, containing a 'use strict' declaration and put them into one file, wrapped up in only one immediately executing function, with only one 'use strict' declaration. How is this normally done? I figured this would be a common use case? Perhaps I'm going about things the wrong way? Should I be using one of the module loading formats (i.e. commonjs, amd)

问题 how to specify a separator in this scenario: I'm concatenating my files with grunt-concat this way: concat: { options: { banner: '<%= banner %>', separator: "" }, dist: { files:{ '<%= distdir %>/public/scripts/ieditor.js': [ 'public/scripts/ieditor/vars.js', 'public/scripts/ieditor/controllers/*.js', 'public/scripts/ieditor/directives/*.js', 'public/scripts/ieditor/app.js', 'public/scripts/ieditor/services/*.js', 'public/scripts/ieditor/filters/*.js' ], '<%= distdir %>/public/scripts