python之如何检查python中是否存在一个值

我正在编写此脚本以使用 python 从 vcenter 中提取性能数据。如果 guest 不存在计数器，则脚本存在/中断。

我将如何首先检查虚拟机是否存在计数器而不是分配值:

这是脚本:

for vmpath in vmlist: 
#Get the current performance manager object (it changes, so we can’t just instatiate it once) 
    pm = server.get_performance_manager() 
    #Get an actual VM object from the path 
    vm = server.get_vm_by_path(vmpath) 
    #Get the managed object reference for the VM, because the performance manager only accepts MoRefs 
    mor = vm._mor 
    #Get all the counters and their current values for that VM. 
    counterValues = pm.get_entity_counters(mor) 
    #Do some quick math on the values. 
    #They come to us in a convienent dictionary form. 
    #Values are descrobed here: http://www.vmware.com/support/developer/vc-sdk/visdk41pubs/ApiReference/virtual_disk_counters.html 
    if InitMyVariable.my_variable is None: 
    cpu_usage=counterValues['cpu.usage'] 
    cpu_ready=counterValues['cpu.ready'] 
    total_memory=counterValues['mem.granted'] 
    memory_used=counterValues['mem.consumed'] 
    Memory_usage=counterValues['mem.usage'] 
    Memory_ballooned=counterValues['mem.vmmemctl'] 
    Memory_swapped=counterValues['mem.swapped'] 
    ReadLatency = counterValues['virtualDisk.totalReadLatency'] 
    WriteLatency = counterValues['virtualDisk.totalWriteLatency'] 
 
    #print them out. 
    print "VM Name",vm.get_property('name') 
    print "% CPU",cpu_usage 
    print "CPU Ready",cpu_ready 
    print "Total Memory",memory_used 
    print "% Memory Used",Memory_usage 
    print "Memory Ballooned",Memory_ballooned 
    print "Memory Swapped",Memory_swapped 
    print "Disk Read Latency",ReadLatency 
    print "Disk Write Latency",WriteLatency 
    print "——-" 
 
server.disconnect() 

这是错误:

Traceback (most recent call last): 
  File "guest_perf.py", line 38, in <module> 
    ReadLatency = counterValues['virtualDisk.totalReadLatency'] 
KeyError: 'virtualDisk.totalReadLatency'