如何检查列表中的数字是否大于它之前的数字-python

Question

I have 3 sets of data zipped together (date,somenumber,price). I want to iterated through the table and whenever somenumber is less than somenumber before it in the list I want to pull the date,somenumber,price for when that happens. Currently I just have:

for a,b,c in zip(date,somenumber,price):
    print(a,b,c)

and it prints something like:

2018-01-30 18:42:00 859235 6.95
2018-02-01 09:08:00 323405 7.43
2018-02-02 15:16:00 528963 6.4
2018-02-05 18:48:00 808739 7.91
2018-02-07 14:42:00 462541 7.33
2018-02-10 18:48:00 598001 6.21
2018-02-11 03:32:00 650558 7.31
2018-02-11 11:28:00 670392 6.21

When somenumber went from 808739 to 462541 I want to return the data for that lower number: 2018-02-07 14:42:00 462541 7.33

Thanks!

Answer 1

This will compare somenumber+1 to somenumber, and if somenumber + 1 (the next number in the sequence is less than the current) it will print all data for that row. If it is not less it will not print anything.

for a,b,c,d in zip(date, somenumber, somenumber[1:], price):
    if c < b:
        print(a, b, c, d)

Answer 2

What I understood from the question is every time, the value of somenumber decreases in the next row, it should print the row. It's very easy to implement. Just store the previous value in another variable ( prev_number ). For the first row, though, we need to initialize prev_number to the minimum number possible. Following is the solution:

import sys
prev_number = -sys.maxint - 1    #initialize prev_number to lowest possible number in python
for a,b,c in zip(date,somenumber,price):
    if b < prev_number:
        print(a,b,c)
    prev_number = d

Let me know if it works for you.