{"id":6690,"date":"2022-05-21T17:37:36","date_gmt":"2022-05-21T09:37:36","guid":{"rendered":"https:\/\/tommykwan.com\/blog\/?p=6690"},"modified":"2022-05-21T18:24:21","modified_gmt":"2022-05-21T10:24:21","slug":"filtering-by-postion-first-one-%e7%ac%ac%e4%b8%80%e5%80%8b-%e7%ac%acx%e5%80%8b-%e6%9f%90%e4%b8%80%e5%80%8b-last-one-%e6%9c%80%e5%be%8c%e4%b8%80%e5%80%8b-%e5%96%ae%e6%95%b8-%e9%9b%99","status":"publish","type":"post","link":"https:\/\/tommykwan.com\/blog\/it\/python\/filtering-by-postion-first-one-%e7%ac%ac%e4%b8%80%e5%80%8b-%e7%ac%acx%e5%80%8b-%e6%9f%90%e4%b8%80%e5%80%8b-last-one-%e6%9c%80%e5%be%8c%e4%b8%80%e5%80%8b-%e5%96%ae%e6%95%b8-%e9%9b%99\/","title":{"rendered":"Filtering by postion : first one (\u7b2c\u4e00\u500b), \u7b2cx\u500b (\u67d0\u4e00\u500b), last one (\u6700\u5f8c\u4e00\u500b), \u55ae\u6578\/\u96d9\u6578"},"content":{"rendered":"

\u5728\u958b\u59cb\u4e4b\u524d\uff0c\u5148\u5b78\u6703COUNT \u4e00\u500b\u5b57\u4e32\u7684\u9577\u5ea6
\nfunction: len()
\n\"\"<\/p>\n

s=\"1234567\"\r\nlen(s)<\/pre>\n
expected result: 7<\/p>\n
 <\/p>\n
\u63a5\u4e0b\u4f86\uff0c\u8981\u8457\u610fpython \u7b2c\u4e00\u500b\u503c\u662f 0 ; \u6700\u5f8c\u4e00\u500b\u503c\u662f -1<\/p>\n
s=”1234567″ # Python initial position is 0 s[0]\n
\u6240\u4ee5first one\u00a0 : s[0]\n
# Python last position is -1\r\ns[-1]<\/pre>\n
\u6240\u4ee5last one\u00a0 : s[-1]\n
\"\"<\/p>\n
 <\/p>\n
\u518d\u4f86\u5c31\u662f\u62bd\u67d0\u4e00\u500b\u7bc4\u570d\u7684\u6578\u503c<\/p>\n
s=”1234567″<\/p>\n
s[x:n] —– \u5176\u4e2dx, n\u70ba\u6578\u5b57; \u4ee3\u8868\u7b2cx\u500b\u4f4d\u7f6e\u958b\u59cb\u62bd\uff0c\u62bd\u5230\u7b2c N-1 \u500b\u4f4d\u7f6e ; \u4f8b\u5b50:<\/p>\n
# \u7531\u7b2cx\u500b\u4f4d\u7f6e\u958b\u59cb\u62bd\uff0c\u62bd\u5230\u7b2c N-1 \u500b\u4f4d\u7f6e\r\n# \u7531\u7b2c0\u500b\u4f4d\u7f6e\u62bd\uff0c\u62bd\u5230\u7b2c 2-1 \u500b\u4f4d\u7f6e\r\n# \u5373\u62bd 0 TO 1\u7684\u6578\u503c\r\ns[0:2]\r\n\r\n\r\n\r\n#\u7531\u7b2c0\u500b\u4f4d\u7f6e\u62bd\uff0c\u62bd\u5230\u7b2c 1-1 \u500b\u4f4d\u7f6e\r\n#\u5373\u62bd0\u7684\u6578\u503cONLY~\r\ns[0:1]\r\n\r\n\r\n\r\n#\u7531\u7b2c1\u500b\u4f4d\u7f6e\u62bd,\u62bd\u52301-1\u500b\u4f4d\u7f6e\r\n#\u5373\u62bd 1 TO 0 \u7684\u6578\u503c - \u660e\u986fLOGIC \u6709\u554f\u984c~\r\ns[1:1]\r\n\r\n\r\n\r\n#\u7531\u7b2c1\u500b\u4f4d\u7f6e, \u62bd\u52302-1\u500b\u4f4d\u7f6e\r\n#\u5373\u62bd1 TO 1\u7684\u6578\u503c\r\ns[1:2]\r\n\r\n\r\n\r\n#\u7531\u7b2c1\u500b\u4f4d\u7f6e\uff0c \u62bd\u5230 3-1\u500b\u4f4d\u7f6e\r\n#\u5373\u62bd1 TO 2 \u7684\u6578\u503c\r\ns[1:3]<\/pre>\n
 <\/p>\n
\u73fe\u5728\uff0c\u518d\u4f86\u4e00\u4e9b\u6df1\u5165\u9ede\u7684\u4f8b\u5b50:<\/p>\n
s[:]\u00a0 \u4ee3\u8868\u5168\u90e8\u90fd\u62bd ;<\/p>\n
s[0:-1]\u00a0 \u4ee3\u8868 \u7531\u7b2c0 TO (\u6700\u5c3e-1) \u500b<\/p>\n
\u6240\u4ee5\u5982\u679c\u60f3\u8981\u57cb\u7b2c\u5f8c\u4e00\u500b\u5c31\u61c9\u8a72\u7528 s[0:]\n
 <\/p>\n
\"\"<\/p>\n
 <\/p>\n
 <\/p>\n
Filtering position \u4ea6\u53ef\u4ee5\u7528\u4f86\u62bd\u55ae\u6578\/\u96d9\u6578\u7684\u503c – \u4f46\u8981\u7528\u5230stepping<\/strong><\/p>\n
\u62bd\u55ae\u6578<\/strong><\/span><\/p>\n
s = \"1234567\"<\/pre>\n
#\u5148\u62bds \u5168\u90e8\uff0c\u518d\u6bcf N + 2\u7684\u62bd<\/p>\n
s [::2]<\/pre>\n
\u5373\u62bd\u7b2c0,2,4,6,8 – \u5c0d\u61c9\u7684\u503c s[0], s[2], s[4], s[6], s[8] ….<\/p>\n
\u6240\u4ee51,3,5,7……..<\/p>\n
\u62bd\u96d9\u6578<\/strong><\/span><\/p>\n
\u5148IGNORE 1\uff0c\u75312\u958b\u59cb\uff0c\u518d\u6bcfN+2\u7684\u62bd<\/p>\n
s[1::2]<\/pre>\n
\u5373\u6703\u5148\u62bd\u4e86 234567 \uff0c\u6bcf\u5c0d\u61c9\u62bds[0], s[2], s[4], s[6], s[8] ….<\/p>\n
\u6240\u4ee52,4,6,8……..<\/p>\n
\"\"<\/p>\n
 <\/p>\n
 <\/p>\n","protected":false},"excerpt":{"rendered":"
\u5728\u958b\u59cb\u4e4b\u524d\uff0c\u5148\u5b78\u6703COUNT \u4e00\u500b\u5b57\u4e32\u7684\u9577\u5ea6 function: len() s=”1234567″ len(s) expected result: 7   \u63a5\u4e0b\u4f86\uff0c\u8981\u8457\u610fpython \u7b2c\u4e00\u500b\u503c\u662f 0 ; \u6700\u5f8c\u4e00\u500b\u503c\u662f -1 s=”1234567″ # Python initial position is 0 s[0] \u6240\u4ee5first one\u00a0 : s[0] # Python last position is -1 s[-1] \u6240\u4ee5last one\u00a0 : s[-1]   \u518d\u4f86\u5c31\u662f\u62bd\u67d0\u4e00\u500b\u7bc4\u570d\u7684\u6578\u503c s=”1234567″ s[x:n] —– \u5176\u4e2dx, n\u70ba\u6578\u5b57; \u4ee3\u8868\u7b2cx\u500b\u4f4d\u7f6e\u958b\u59cb\u62bd\uff0c\u62bd\u5230\u7b2c N-1 \u500b\u4f4d\u7f6e ; \u4f8b\u5b50: # \u7531\u7b2cx\u500b\u4f4d\u7f6e\u958b\u59cb\u62bd\uff0c\u62bd\u5230\u7b2c N-1 \u500b\u4f4d\u7f6e Read More<\/span><\/a><\/p>\n","protected":false},"author":1,"featured_media":0,"comment_status":"closed","ping_status":"open","sticky":false,"template":"","format":"standard","meta":{"footnotes":""},"categories":[28],"tags":[],"class_list":["post-6690","post","type-post","status-publish","format-standard","hentry","category-python"],"_links":{"self":[{"href":"https:\/\/tommykwan.com\/blog\/wp-json\/wp\/v2\/posts\/6690","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/tommykwan.com\/blog\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/tommykwan.com\/blog\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/tommykwan.com\/blog\/wp-json\/wp\/v2\/users\/1"}],"replies":[{"embeddable":true,"href":"https:\/\/tommykwan.com\/blog\/wp-json\/wp\/v2\/comments?post=6690"}],"version-history":[{"count":12,"href":"https:\/\/tommykwan.com\/blog\/wp-json\/wp\/v2\/posts\/6690\/revisions"}],"predecessor-version":[{"id":6707,"href":"https:\/\/tommykwan.com\/blog\/wp-json\/wp\/v2\/posts\/6690\/revisions\/6707"}],"wp:attachment":[{"href":"https:\/\/tommykwan.com\/blog\/wp-json\/wp\/v2\/media?parent=6690"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/tommykwan.com\/blog\/wp-json\/wp\/v2\/categories?post=6690"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/tommykwan.com\/blog\/wp-json\/wp\/v2\/tags?post=6690"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}