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How to index into a dictionary?
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Dictionaries are unordered in Python versions up to and including Python 3.6. If you do not care about the order of the entries and want to access the keys or values by index anyway, you can use d.keys()[i] and d.values()[i] or d.items()[i]. (Note that these methods create a list of all keys, va...
Why should eval be avoided in Bash, and what should I use instead?
...# Arguments to printf:
# 1 -> "$1\n"
# 2 -> "$2"
# 3 -> "$3"
# 4 -> "$4"
# etc.
printf "$1\n" "${@:2}"
}
function error
{
# Send the first element as one argument, and the rest of the elements as a combined argument.
# Arguments to println:
...
get list from pandas dataframe column
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534
Pandas DataFrame columns are Pandas Series when you pull them out, which you can then call x.to...
Why do enum permissions often have 0, 1, 2, 4 values?
...are people always using enum values like 0, 1, 2, 4, 8 and not 0, 1, 2, 3, 4 ?
7 Answers
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Get: TypeError: 'dict_values' object does not support indexing when using python 3.2.3 [duplicate]
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3 Answers
3
Active
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How to select rows with one or more nulls from a pandas DataFrame without listing columns explicitly
I have a dataframe with ~300K rows and ~40 columns.
I want to find out if any rows contain null values - and put these 'null'-rows into a separate dataframe so that I could explore them easily.
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Replace all 0 values to NA
...me space for it. E.g.,
data.frame(x = c(1, NA, 2))
# x
# 1 1
# 2 NA
# 3 2
Also, the data frame structure requires all the columns to have the same number of elements so that there can be no "holes" (i.e., NULL values).
Now you could replace zeroes by NULL in a data frame in the sense of com...
What does the “yield” keyword do?
...ng its items one by one is called iteration:
>>> mylist = [1, 2, 3]
>>> for i in mylist:
... print(i)
1
2
3
mylist is an iterable. When you use a list comprehension, you create a list, and so an iterable:
>>> mylist = [x*x for x in range(3)]
>>> for i in my...
Element-wise addition of 2 lists?
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371
Use map with operator.add:
>>> from operator import add
>>> list( map(add, ...
Select multiple columns in data.table by their numeric indices
... all just work:
library(data.table)
dt <- data.table(a = 1, b = 2, c = 3)
# select single column by index
dt[, 2]
# b
# 1: 2
# select multiple columns by index
dt[, 2:3]
# b c
# 1: 2 3
# select single column by name
dt[, "a"]
# a
# 1: 1
# select multiple columns by name
dt[, c("a", ...