Use: np.concatenate([a, b]) The arrays you want to concatenate need to be passed in as a sequence, not as separate arguments. From the NumPy documentation: numpy.concatenate((a1, a2, …), axis=0) Join a sequence of arrays together. It was trying to interpret your b as the axis parameter, which is why it complained it couldn’t convert it … Read more
NOTE: The method used in this answer (backticks) is deprecated in later versions of Python 2, and removed in Python 3. Use the str() function instead. You can use: string = ‘string’ for i in range(11): string +=`i` print string It will print string012345678910. To get string0, string1 ….. string10 you can use this as … Read more
Legacy. List was originally defined to be functional-languages-looking: 1 :: 2 :: Nil // a list list1 ::: list2 // concatenation of two lists list match { case head :: tail => “non-empty” case Nil => “empty” } Of course, Scala evolved other collections, in an ad-hoc manner. When 2.8 came out, the collections were … Read more
In C, “strings” are just plain char arrays. Therefore, you can’t directly concatenate them with other “strings”. You can use the strcat function, which appends the string pointed to by src to the end of the string pointed to by dest: char *strcat(char *dest, const char *src); Here is an example from cplusplus.com: char str[80]; … Read more
The + operator is not defined for arrays. What happens is that Javascript converts arrays into strings and concatenates those. Update Since this question and consequently my answer is getting a lot of attention I felt it would be useful and relevant to have an overview about how the + operator behaves in general … Read more
The best way of appending a string to a string variable is to use + or +=. This is because it’s readable and fast. They are also just as fast, which one you choose is a matter of taste, the latter one is the most common. Here are timings with the timeit module: a = … Read more
SELECT id, GROUP_CONCAT(name SEPARATOR ‘ ‘) FROM table GROUP BY id; https://dev.mysql.com/doc/refman/8.0/en/aggregate-functions.html#function_group-concat From the link above, GROUP_CONCAT: This function returns a string result with the concatenated non-NULL values from a group. It returns NULL if there are no non-NULL values.
Was looking for the same thing, and found this to suggest: tail -n +1 file1.txt file2.txt file3.txt Output: ==> file1.txt <== <contents of file1.txt> ==> file2.txt <== <contents of file2.txt> ==> file3.txt <== <contents of file3.txt> If there is only a single file then the header will not be printed. If using GNU utils, you … Read more
No, not quite. Firstly, there’s a slight difference in semantics. If a is null, then a.concat(b) throws a NullPointerException but a+=b will treat the original value of a as if it were null. Furthermore, the concat() method only accepts String values while the + operator will silently convert the argument to a String (using the … Read more
Use str.join: >>> words = [‘this’, ‘is’, ‘a’, ‘sentence’] >>> ‘-‘.join(words) ‘this-is-a-sentence’ >>> ‘ ‘.join(words) ‘this is a sentence’