Sample random rows in dataframe?

I am struggling to find the appropriate function that would return a specified number of rows picked up randomly without replacement from a data frame in R language? Can anyone help me out?


Converting from a string to boolean in Python?

Does anyone know how to do convert from a string to a boolean in Python? I found this link. But it doesn't look like a proper way to do it. I.e. using a built in functionality, etc.The reason I... more


How to subtract a day from a date?

I have a Python datetime.datetime object. What is the best way to subtract one day?


How to remove the first Item from a list?

I have the list [0, 1, 2, 3, 4] I'd like to make it into [1, 2, 3, 4]. How do I go about this?


How do I check the file size in python?

I am writing a Python script in Windows. I want to do something based on the file size. For example, if the size is greater than 0, I will send an email to somebody, otherwise continue to other... more


How do you measure time elapsed in Python?

What I want is to start counting time somewhere in my code and then get the passed time, to measure the time it took to execute few function. I think I'm using the timeit module wrong, but the docs... more


Getting the length of an array in Python

In Python, is the following the only way to get the number of elements?arr.__len__()If so, why the strange syntax?


How do you add new keys to an existing Python dictionary?

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