Shulou(Shulou.com)06/02 Report--

This article mainly introduces the little-known Python functions, the article is very detailed, has a certain reference value, interested friends must read it!

Divmod

This is a very useful function. The function performs a modular division% operation on two numbers and then returns quotient and remainder. For example:

Divmod (5,2) [Out]: (2,1)

This is just finding the number of times we can fit 2 into 5, and we don't need to split this number to get a quotient of 2 and 1 as the remainder.

This is particularly useful for calculating the time it takes for the return process to run. It's like this:

Start = datetime.datetime.now ()... # process code end = datetime.datetime.now () # gets the total elapsed time (seconds) runtime = (end-start). How many hours are there in these seconds if seconds # is 30000 # and what are the remaining seconds? Hours, remainder = divmod (runtime, 3600) # how much time is left now? Mins, secs = divmod (remainder, 60) print ("{: 02d}: {: 02d}: {: 02d}" .format (hours, mins, secs)) [Out]: "08:00:08"

* args, * * kwargs

Sometimes you may notice that the function definition contains these two parameters, such as def func (x _ args,** kwargs).

They are actually very simple functions. Both allow us to pass multiple values to a function and then package it into a generator.

The result is similar to whether to pass the list / generator to the standard parameter:

Def func (values): for x in values: print (x, end= "") func ([1,2,3]) [Out]:'1 2 3'

Now let's use * args- we should pass each value as a new parameter instead of including them all in the list.

Def func (* values): for x in values: print (x, end= "") func (1, 2, 3) [Out]: 1 2 3

Note that we don't need to enter * args, just enter * values. Because of the single asterisk *, it is defined as * args, regardless of the variable name we use.

* args simply creates a tuple based on the parameters we pass to the function.

* * kwargs creates a dictionary. Therefore, we can use the name, keyword argument:

Def func (* * values): for x in values: print (f "{x}: {values [x]}") func [Out]: X: 1 y: 2 z: 3

Again, we can call variables at will, in which case we use * * values. Define it as * * kwargs by using double quotes.

List understanding

This is definitely one of the most useful features of Python, and understanding expressions is essential. The most common is list understanding, and I'm sure most of you have read the following:

Vals = [1, 2, 3, 4, 5] [for i in vals 2] [Out]: [1, 4, 9, 16, 25]

But we are not limited to these square brackets. We can define generator expressions with almost exactly the same syntax:

(iTune2 for i in vals) [Out]:

Of course, each element in the generator is output only when it is called, and we can use list () to do this:

List ((iTune2 for i in vals)) [Out]: [1, 4, 9, 16, 25]

With only a small change to the syntax, we can even use dictionary understanding to build a dictionary:

{I: iTunes 2 for i in vals} [Out]: {1: 1, 2: 4, 3: 9, 4: 16, 5: 25}

Casefold

This is a particularly interesting string method, and its function is similar to reduction. However, casefold tries to standardize a wider range of characters more aggressively.

In most cases, lowercase and uppercase collapse behave the same, but sometimes they are not the same:

Casefold () # and σ are both Greek letters sigma [Out]: "σ"

In contrast, the use is lower:

Lower () # but the lower thinks they are different [Out]: "Out" [Out]: False

In this case, both sigma are already lowercase. Depending on usage, it may work as expected.

However, if we are going to compare two equivalent Greek words, one uses sigma and the other uses Greek. Although the same, only casefold allows us to compare them accurately:

[Out]: False "ρ μ η σ". Lower () = = "ρ μ η σ" .lower () [Out]: False "ρ μ η σ" .casefold () = = "ρ μ η η σ" .casefold (): True is all the contents of the article "what are the little-known functions of Python". Thank you for reading! Hope to share the content to help you, more related knowledge, welcome to follow the industry information channel!

Welcome to subscribe "Shulou Technology Information " to get latest news, interesting things and hot topics in the IT industry, and controls the hottest and latest Internet news, technology news and IT industry trends.