Python colon not a sequence of numbers?

Question

In r code, the sequence of integers from 1 to 4:

1:4

How can I replicate this in python 3? The use case is selecting from a pandas dataframe using iloc:

df.iloc[1:4]

I'm pretty sure your current syntax allows you to select rows 1 to 3 from the dataframe as well. See https://pandas.pydata.org/pandas-docs/stable/reference/api/pandas.DataFrame.iloc.html — absolutelydevastated, Sep 09 '19 at 17:29
Note that `df.iloc[1:4]` is essentially just syntactic sugar for `df.iloc[slice(1,4)]`; it's unrelated to the generation of an actual sequence of integers. It's up to the particular implementation of `__getitem__` that receives that `slice` object to decide how exactly to treat it. — chepner, Sep 09 '19 at 17:39

Hetal Thaker · Accepted Answer · 2019-09-09T17:43:05.550

1

You can use

mylist=list(range(1,5))
print(mylist)

list() converts given range object into list

edited Sep 09 '19 at 17:43

answered Sep 09 '19 at 17:35

Hetal Thaker

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There is no `range` object, because your code produces a syntax error. – chepner Sep 09 '19 at 17:41
Yeah i agree, there should be , instead of : – Hetal Thaker Sep 09 '19 at 17:42
Now you may check this please. – Hetal Thaker Sep 09 '19 at 17:46

lmiguelvargasf · Answer 2 · 2019-09-09T17:30:49.107

0

In Python, in order to generate a range of numbers use the function range.

range(1, 5)

This will generate numbers from 1 to 4. If you are in Python 2, range will give you a list, and if you are in Python 3, it will give you a range object.

If you are in Python 3, and you want a list, just use the list function to convert your range to a list

>>> list(range(1, 5)
[1, 2, 3, 4]

edited Sep 09 '19 at 17:30

answered Sep 09 '19 at 17:28

lmiguelvargasf

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Thank you. I'm used to python 2 range. What if I want a list of numbers and not range object? – DDDD Sep 09 '19 at 17:29

score 0 · Answer 3 · answered Sep 09 '19 at 17:29

0

Use range(1, 5) for giving you that set of integers from 1 to 4 (inclusive of both)

answered Sep 09 '19 at 17:29

Matthew Gaiser

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J-L · Answer 4 · 2019-09-09T23:16:58.783

To generate a range of number from 1 to 4 (inclusive), use: range(1, 5) or range(1, 4+1)

Just a few things to note:

The code range(x, y) generates a range from (and including) x up to (but not including) y. If you want to include y, add 1 to it (as I did above).
range(x, y) works a bit differently in Python 2 vs. Python 3. I won't go into the details here, but I recommend using Python 3 (which hopefully you're already using).
range(x) is will generate a range from (and including) zero up to (but not including) x. So range(x) is basically the same as range(0, x).
The range function will generate a range object; that is, it doesn't actually create a list of all the integers between x and y. If you do want a list of integers between x and y, use this code:
```
some_list = list(range(x, y))
```

However, if you're looking to pull out a slice of values out of a sequential container, this might work:

from itertools import islice
values = islice(df.iloc, 1, 5)  # returns an iterator
values = list(values)  # extracts the values from the iterator into a list

score 0 · Answer 5 · answered Sep 09 '19 at 17:56

Python's slicing syntax doesn't produce a range of integers; it produces one or more slice objects which are passed to the __getitem__ method of the appropriate type. That is,

df.iloc[1:4]

is equivalent to either

def.iloc[slice(1,4)]

or

df.iloc.__getitem__(slice(1,4))

Python colon not a sequence of numbers?

5 Answers5