{"kind":"task","effective_mode":"full","benchmark":{"kind":"benchmark","effective_mode":"full","slug":"ds-1000","formal_name":"DS-1000","introduction":"DS-1000 builds 1,000 data-science problems from real StackOverflow questions across seven libraries including NumPy, Pandas and Matplotlib. The problems are perturbed so that recalling the original answer does not solve them.","introduction_ja":"","introduction_en":"","category":"Category not supplied","task_count":null,"acquisition_status":"Acquisition status not supplied","official_url":"https://ds1000-code-gen.github.io/","indexing_mode":"index","profile":{"resources":[],"task_format":"","scoring":"","metric":"","size":"","answer_access":"","license":"","citation":"","maintainer":"","released":"","why_hard":"","related":[],"history":"","construction":"","limitations":"","saturation":"","scores":[]}},"task_id":"9247fd19-e34f-5f45-85b4-6c9abb2dcb80","task_key":"default--test--398","task_revision_id":"1","upstream_id":"398","short_description":"I have a time-series A holding several values. I need to obtain a series B that…","config":"default","split":"test","body":"{\"library\":\"Numpy\",\"prompt\":\"Problem:\\nI have a time-series A holding several values. I need to obtain a series B that is defined algebraically as follows:\\nB[0] = a*A[0]\\nB[t] = a * A[t] + b * B[t-1]\\nwhere we can assume a and b are real numbers.\\nIs there any way to do this type of recursive computation in Pandas or numpy?\\nAs an example of input:\\n> A = pd.Series(np.random.randn(10,))\\n0   -0.310354\\n1   -0.739515\\n2   -0.065390\\n3    0.214966\\n4   -0.605490\\n5    1.293448\\n6   -3.068725\\n7   -0.208818\\n8    0.930881\\n9    1.669210\\nA:\\n<code>\\nimport numpy as np\\nimport pandas as pd\\nA = pd.Series(np.random.randn(10,))\\na = 2\\nb = 3\\n</code>\\nB = ... # put solution in this variable\\nBEGIN SOLUTION\\n<code>\\n\"}","display_format":"code","language":"","answer_status":"published","assets":[],"source_url":"https://ds1000-code-gen.github.io/","history":"initial import","indexing_mode":"index","subproblems":[],"grids":[]}