Barnaby questions

• Location in a vector of a certain value, applying the mentioned location to extract the value from another vector
• Append individual vectors in a list to specific positions within another list
• Extract Consecutive Pairs of Elements from a Vector and Place in a Matrix
• Counting the frequency of an element in a data frame [duplicate]
• Add a series of elements in different locations within a vector
• Remove columns with zero values from a dataframe

Barnaby answers