concatenation | 易学教程

Perl - concatenating a undefined number of strings into one string

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问题 I need to concatenate an undefined number of strings with Perl to create one larger string. $concatenated_string = $string1 . $string2 . $string3 #..and so on for all strings provided in the file which was opened earlier in the program. I am just a beginner, but I could not find any question on here relating to it. Any help is much appreciated. 回答1: As I have mentioned elsewhere: When you find yourself adding an integer suffix to variable names, think " I should have used an array ". Then you

Preserving Column Order - Python Pandas and Column Concat

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So my google-fu doesn't seem to be doing me justice with what seems like should be a trivial procedure. In Pandas for Python I have 2 datasets, I want to merge them. This works fine using .concat. The issue is, .concat reorders my columns. From a data retrieval point of view, this is trivial. From a "I just want to open the file and quickly see the most important column" point of view, this is annoying. File1.csv Name Username Alias1 Tom Tomfoolery TJZ Meryl MsMeryl Mer Timmy Midsize Yoda File2.csv Name Username Alias 1 Alias 2 Bob Firedbob Fire Gingy Tom Tomfoolery TJZ Awww Result.csv Alias1

Excel 2010 VBA. Concatenate 2 columns from a Sheet and paste them in another

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问题 Using Excel 2010, I'm trying to create a script that concatenates two text columns (A and B) from Sheet1 and pastes the result in column A of Sheet2. The workbook uses an external datasource for loading both columns, so the number of rows is not fixed. I've tried the following code, but not working. variable lRow is not taking any value. Sub Concat() Sheets("Sheet1").Select Dim lRow As Long lRow = Range("A" & Rows.count).End(xlUp).Row For i = 2 To lRow ActiveWorkbook.Sheets("Sheet2").Cells(i,

How to concatenate videos in ffmpeg with different attributes?

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问题 I'm trying to merge some videos but I'm getting timestamp errors. I tried to make them all equal with the same dimensions, frame rate, sample rate and also by adding an audio track when there's none. lista = ['1.mp4', '2.mp4', '3.mp4'] path = '/Downloads/abc/' a = open('/Downloads/abc/list.txt', 'w+') i = 0 for f in lista: i += 1 places = path + str(i) + 'test.mp4' res = path + str(i) + 'fixtest.mp4' bb = check_output(shlex.split('ffprobe -i ' + f + ' -show_streams -select_streams a -loglevel

Fast concatenation of data.table columns into one string column

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Given an arbitrary list of column names in a data.table , I want to concatenate the contents of those columns into a single string stored in a new column. The columns I need to concatenate are not always the same, so I need to generate the expression to do so on the fly. I have a sneaking suspicion that way I'm using the eval(parse(...)) call could be replaced with something a bit more elegant, but the method below is the fastest I've been able to get it so far. With 10 million rows, this takes about 21.7 seconds on this sample data (base R paste0 takes slightly longer -- 23.6 seconds) . My

Select out of a combined view with concatenation not working? [duplicate]

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问题 This question already has answers here : What is the string concatenation operator in Oracle? (4 answers) Closed last year . I tried creating a view with two values in one column using + , and the view was created successfully, but when I try selecting all from it it gives me this error: select * * ERROR at line 1: ORA-01722: invalid number I tried researching this and the concatenation operator but to my dismay have found no help. Here is the code I used to create the view, and the select

String replace and concatenation

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问题 I have this structure <ROWS> <ROW> <TEXT> This is a @good@ @day@ </TEXT> <good>great</good> <day>month</day> </ROW> <ROW> <TEXT> This is a @good@ @day@ </TEXT> <good>Fun</good> <day>morning</day> </ROW> </ROWS> How do I change that to <statement> This is a great month, this is a Fun morning </statement> Using only XSLT 1.0? The original XML can change tag name. But not the structure! Any ideas? 回答1: This seems somewhat similar to creating form letters from a template. Assuming the example is

How can I concatenate a vector? [duplicate]

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This question already has an answer here: Concatenate a vector of strings/character 5 answers I'm trying to produce a single variable which is a concatenation of two chars e.g to go from "p30s4" "p28s4" to "p30s4 p28s4". I've tried cat and paste as shown below. Both return empty variables. What am I doing wrong? > blah = c("p30s4","p28s4") > blah [1] "p30s4" "p28s4" > foo = cat(blah) p30s4 p28s4 > foo NULL > foo = paste(cat(blah)) p30s4 p28s4 > foo character(0) Try using: > paste(blah, collapse = "") [1] "p30s4p28s4" or if you want the space in between: > paste(blah, collapse = " ") [1] "p30s4

What's the difference between concat and uglify and minify?

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What's the difference between concat, uglify, and minify tasks in grunt? I set up an uglify task for all of my site's javascript tasks, and it seemed to both minify and concatenate them. Grunt's site has a great description for how to configure each task, but it doesn't seem to explain what each task actually does. diclophis Concatenation is just appending all of the static files into one large file . Minification is just removing unnecesary whitespace and redundant / optional tokens like curlys and semicolons, and can be reversed by using a linter. Uglification is the act of transforming the

CONCAT'ing NULL fields

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I have a table with three fields, FirstName, LastName and Email. Here's some dummy data: FirstName | LastName | Email Adam West adam@west.com Joe Schmoe NULL Now, if I do: SELECT CONCAT(FirstName, LastName, Email) as Vitals FROM MEMBERS Vitals for Joe is null, as there is a single null field. How do you overcome this behaviour? Also, is this the default behaviour in MS SQL Server? Stefan Mai Try ISNULL(FirstName, '<BlankValue>') -- In SQL Server IFNULL(Firstname, '<BlankValue>') -- In MySQL So, CONCAT(ISNULL(FirstName,''),ISNULL(LastName,''),ISNULL(Email,'')) -- In SQL Server CONCAT(IFNULL