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原创 factor(), tapply()
factor(), ordered()tapply()tapply(X, INDEX, FUN = NULL, …, default = NA, simplify = TRUE)
2019-10-09 15:20:17
182
原创 import data into R
read.tableread.csvopenxlsxinstall.packages(“openxlsx”)library(openxlsx)read.xlsx(file,header)
2019-10-09 15:00:47
288
原创 array, matrix, list, dataframe
arrayarray can be k dimensionalconstruct arrays by the array function:Z <- array(data_vector, dim_vector)For example, if the vector h contains 24 or fewer, numbers then the commandZ <-...
2019-10-09 14:32:05
214
原创 list, array, matrix(列表,数组,矩阵)
list是python中的普通列表对象,而array和matrix是python numpy库中封装的两个对象Listlist可以明显的与array,matrix区别开来。list通过[ ]申明,支持append和expend等方法,没有shape属性。使用如下:>>> data = []>>> data.append([1,2])>>...
2019-10-07 12:54:29
976
原创 if __name__ == '__main__'
# const.pyPI=3.14def train(): print("PI:",PI)train()# area.pyfrom const import PI def calc_round_area(radius): return PI * (radius ** 2) def calculate(): print("round area: ", ...
2019-10-07 12:54:20
100
原创 information hiding
Use naming conventions to make data attributes and methods invisible outside the classConvention: Begin name with __ but do not end with itclass InfoHiding(object): def __init__(self): ...
2019-09-26 15:56:33
259
原创 functions, modules
‘Build-in’len()max()range()open()Defining a functiondef function_name(list of parameters):body of functionCalling a functionfunction_name(arguements)When the Function is used, the para...
2019-09-26 11:31:07
107
原创 data type, arithemetic operators
Numeric Type: int, float, complexSequence Type: list, tuple, rangeText Type: strSet Type: set, frozensetMapping Type: dictStoring Matrix Data: list, array, matrix
2019-09-25 16:17:45
133
原创 variables, name of objects
Variables, Name of objectsIf you’re coming to Python from a language in the C/Java/etc. family, it may help you to stop thinking about a as a “variable”, and start thinking of it as a “name”.a, b, a...
2019-09-24 17:01:42
133
原创 slice
SliceNotationa[start:stop] # items start through stop-1a[start:] # items start through the rest of the arraya[:stop] # items from the beginning through stop-1a[:] # a copy o...
2019-09-24 16:47:07
96
原创 python practice
Decode a web page链接: practice1 practice2模块: requests, BeautifulSoup
2019-09-24 16:42:08
197
2018_FRM_Part_II_Quicksheet_公式表
2018-12-02
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