How to open a file using the open with statement

Python allows putting multiple open() statements in a single with. You comma-separate them. Your code would then be: And no, you don’t gain anything by putting an explicit return at the end of your function. You can use return to exit early, but you had it at the end, and the function will exit without it. (Of course with functions that return … Read more

Understanding slice notation

It’s pretty simple really: There is also the step value, which can be used with any of the above: The key point to remember is that the :stop value represents the first value that is not in the selected slice. So, the difference between stop and start is the number of elements selected (if step is 1, the default). The other feature is that start or stop may be a negative number, which … Read more

Understanding the main method of python [duplicate]

The Python approach to “main” is almost unique to the language(*). The semantics are a bit subtle. The __name__ identifier is bound to the name of any module as it’s being imported. However, when a file is being executed then __name__ is set to “__main__” (the literal string: __main__). This is almost always used to separate the portion of code which should … Read more

Why am I seeing “TypeError: string indices must be integers”?

item is most likely a string in your code; the string indices are the ones in the square brackets, e.g., gravatar_id. So I’d first check your data variable to see what you received there; I guess that data is a list of strings (or at least a list containing at least one string) while it should be a list of dictionaries.

how to sort pandas dataframe from one column

Use sort_values to sort the df by a specific column’s values: If you want to sort by two columns, pass a list of column labels to sort_values with the column labels ordered according to sort priority. If you use df.sort_values([‘2’, ‘0’]), the result would be sorted by column 2 then column 0. Granted, this does not really make sense for this example because … Read more

How to define a two-dimensional array?

You’re technically trying to index an uninitialized array. You have to first initialize the outer list with lists before adding items; Python calls this “list comprehension”. #You can now add items to the list: Note that the matrix is “y” address major, in other words, the “y index” comes before the “x index”. Although you … Read more

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