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...
multiline_string = '''This is a string where I can confortably write on multiple lines without worring about to use the escape character "\\" as in the previsou example. As you'll see, the original string formatting is preserved. ''' print(multiline_string) 改变大小写 你可以很方便的...
In Python, astringis a sequence of characters. A multi-line string is a string that spans across multiple lines of code. Multi-line strings can be created using either triple quotes or escape characters. Triple quotes are either single quotes (''') or double quotes (""") that allow you...
tostr): 62 """maketrans(frm, to) -> string 63 64 Return a translation table (a string of 256 bytes long) 65 suitable for use in string.translate. The
本章经过大幅编辑,比第一版《流畅的 Python》中对应的第十一章长约 24%。虽然有些部分和许多段落是相同的,但也有很多新内容。以下是亮点: 本章的介绍和类型映射(图 13-1)是新内容。这是本章和所有涉及 Python ≥ 3.8 中类型的其他章节中大部分新内容的关键。
string.endswith() Returns True if a string ends with the specified suffix (case-sensitive), otherwise returns False. string.expandtabs() Returns a string with all tab characters \t replaced with one or more space, depending on the number of characters before \t and the specified tab size. ...
Perform a string formatting operation. 应该和 原来的 % 差不多。 参考文档:文档 str.index(sub[, start[, end]]) Like find(), but raise ValueError when the substring is not found str.isalnum() Return true if all characters in the string are alphanumeric and there is at least one character...
lines.append(key +' '+ desc) data ='\n'.join(lines) file = open(filename,'w') file.write(data) file.close()# save descriptionssave_doc(descriptions,'descriptions.txt') 汇总起来,完整的函数定义如下所示: importstring# load doc into memorydefload_doc(filename):# open the file as read...
Sometimes we try to print our string to multiple lines also and in that case what happens is that, let’s see this with an example: 有时我们也尝试将字符串打印到多行,在这种情况下会发生什么,让我们看一个例子: def multiLine(): return "This is a new line ...
这在由Tim Peters写的Python格言(称为The Zen of Python)里面表述为:There should be one-- and preferably only one --obvious way to do it. 这正好和Perl语言(另一种功能类似的高级动态语言)的中心思想TMTOWTDI(There's More Than One Way To Do It)完全相反。