You want sed –in-place ‘s/[[:space:]]\+$//’ file That will delete all POSIX standard defined whitespace characters, including vertical tab and form feed. Also, it will only do a replacement if the trailing whitespace actually exists, unlike the other answers that use the zero or more matcher (*). –in-place is simply the long form of -i. I … Read more
Use table.put(key, val); to add a new key/value pair or overwrite an existing key’s value. From the Javadocs: V put(K key, V value): Associates the specified value with the specified key in this map (optional operation). If the map previously contained a mapping for the key, the old value is replaced by the specified value. … Read more
lista = list.sort(lista) This should be lista.sort() The .sort() method is in-place, and returns None. If you want something not in-place, which returns a value, you could use sorted_list = sorted(lista) Aside #1: please don’t call your lists list. That clobbers the builtin list type. Aside #2: I’m not sure what this line is meant … Read more
Note: using in-place operations on NumPy arrays that share memory in no longer a problem in version 1.13.0 onward (see details here). The two operation will produce the same result. This answer only applies to earlier versions of NumPy. Mutating arrays while they’re being used in computations can lead to unexpected results! In the example … Read more
From the dropna docstring: Drop the columns where all elements are NaN: df.dropna(axis=1, how=’all’) A B D 0 NaN 2.0 0 1 3.0 4.0 1 2 NaN NaN 5
This post addresses the question about the absence of the equivalent of sed’s “-i” option, and in particular the situation described: I have a bunch of files and writing each one to a separate file wouldn’t be easy. There are several options, at least if you are working in a Mac or Linux or similar … Read more
When inplace=True is passed, the data is renamed in place (it returns nothing), so you’d use: df.an_operation(inplace=True) When inplace=False is passed (this is the default value, so isn’t necessary), performs the operation and returns a copy of the object, so you’d use: df = df.an_operation(inplace=False)
Well, here’s a simple implementation of an MSD radix sort for DNA. It’s written in D because that’s the language that I use most and therefore am least likely to make silly mistakes in, but it could easily be translated to some other language. It’s in-place but requires 2 * seq.length passes through the array. … Read more
You can use the -i flag correctly by providing it with a suffix to add to the backed-up file. Extending your example: sed -i.bu ‘s/oldword/newword/’ file1.txt Will give you two files: one with the name file1.txt that contains the substitution, and one with the name file1.txt.bu that has the original content. Mildly dangerous If you … Read more
sorted() returns a new sorted list, leaving the original list unaffected. list.sort() sorts the list in-place, mutating the list indices, and returns None (like all in-place operations). sorted() works on any iterable, not just lists. Strings, tuples, dictionaries (you’ll get the keys), generators, etc., returning a list containing all elements, sorted. Use list.sort() when you … Read more