Get first element of Series without knowing the index
122146
Pandas - Get first row value of a given column
18194
Return first digit of an integer
67150
Index with exercise numbers
149895
A more convenient Fourier series
36864
How should I iterate over a sparse array in index order?
19258
Get index of element as child relative to parent
112343
vectorized array creation from a list of start/end indices
29804
Summation with jump indices like 1,4,6,9?
113191
How to get the index of an element in an IEnumerable?
18338
Find the next element that is not immediate?
31062
Elegant way to remove items from sequence in Python?
137135
Providing an iterator for the first element of a container of pairs
67180
Manipulating infinite series
59380
Get first key in a (possibly) associative array?
101187
Fubini's theorem for series with dependent indices
57008
How can I fill a unitary knowing only its first column?
99354
Listing elements starting from 0