read_csv( 'large.csv', chunksize=chunksize, dtype=dtype_map ) # # 然后每个chunk进行一些压缩内存的操作,比如全都转成sparse类型 # string类型比如,学历,可以转化成sparse的category变量,可以省很多内存 sdf = pd.concat( chunk.to_sparse(fill_value=0.0) for chunk in chunks ) #很稀疏有可能可以装的下...
这是Python 关键字的完整列表: FalseawaitelseimportpassNonebreakexceptinraiseTrueclassfinallyisreturnandcontinueforlambdatryasdeffromnonlocalwhileassertdelglobalnotwithasyncelififoryield 你不需要记住这个列表。在大多数开发环境中,关键字会以不同的颜色显示;如果你尝试将其作为变量名使用,你会知道的。 2.4. 导入...
打开安装好的PyCharm。 创建一个Python文件。 ctrl+shift+f10运行代码。 二、基础语法 1、常量和表达式 形如1+2-1 称之为表达式,这个表达式的运算结果称之为表达式的返回值。1 2 3 这样的数字称之为字面值常量,+ - * / 称之为运算符/操作符。 print(1+2-1)print(1+2*3)print(1+2/3) 1. 2. 3...
# multiple.sequences.explicit.pypeople = ['Conrad','Deepak'
print(lines) # 输出:['第一行\n', '第二行\n', ...] 1. 2. 3. 4)文件写入操作 1. 覆盖写入 with open('output.txt', 'w', encoding='utf-8') as f: f.write("Hello, World!\n") # 写入字符串 f.writelines(["第一行\n", "第二行\n"]) # 写入列表(不自动添加换行符) ...
>>> myvar, mystring = mystring, myvar 数据类型 Python具有列表(list)、元组(tuple)和字典(dictionaries)三种基本的数据结构,而集合(sets)则包含在集合库中(但从Python2.5版本开始正式成为Python内建类型)。列表的特点跟一维数组类似(当然你也可以创建类似多维数组的“列表的列表”),字典则是具有关联关系的数组(...
You can use single and double quotes for a single line of characters. Multiple lines are generally put in triple quotes.String common methodsGet the index of a substring in a string. # find the index of a "c" in a string "abcde" >>> "abcde".index("c") 2...
word = 'word'sentence = "This is a sentence."paragraph = """This is a paragraph. It ismade up of multiple lines and sentences.""" 1.3.3 Python注释 “#”号之后字符和到物理行是注释的一部分,Python解释器会忽略它们。 #!/usr/bin/python# First commentprint "Hello, Python!"; # second co...
Shells typically do their own tokenization, which is why you just write the commands as one long string on the command line. With the Python subprocess module, though, you have to break up the command into tokens manually. For instance, executable names, flags, and arguments will each be ...
Functionally, this is the same as writing it all out as one single string:r"\[(.+)\] [-T:+\d]{25} : (.+)". Organizing your longer regex patterns on separate lines allow you to break it up into chunks, which not only makes it more readable but also allow you to insert comment...